/* abort.c */
#include <stdio.h>
#include <stdlib.h>

main(){
	int x, y;
	printf("Please input two integers(x,y) for division除數: ");
	scanf("%d %d", &x, &y);
	system("color 2E");

	/*  Is the divisor zero?  */
	if ( y==0 ) {
		printf( "Sorry, the divisor can't be ZERO!\a\n" );
		abort();	// 取消執行
	}

	/*  Print the result.  */
	printf("%d / %d = %d\n", x, y, x/y);
	system("pause");
}

/* abs.c */
#include <stdlib.h>
main(){
	int num, abs_num;
	printf("請輸入一整數: ");
	scanf("%d", &num);
	abs_num=abs(num);
	printf("此數 %i 的絕對值為: %d\n", num, abs_num);
}

/* access.c (存取權限) szeto */
#include <stdio.h>
#include <unistd.h>
main(){
	// R_OK=4,W_OK=2,X_OK=1,F_OK=0
	printf("R_OK=%i\n", access("exp.exe",R_OK));
	printf("W_OK=%i\n", access("exp.exe",W_OK));
	printf("X_OK=%i\n", access("exp.exe",X_OK));
	printf("F_OK=%i\n", access("exp.exe",F_OK));

	printf("F_OK=%i\n", access("not-exist.txt",F_OK));	// -1
}

/* acos.c */
#include <math.h>
#include <errno.h>
#include <stdlib.h>
#define RadianToDegree 57.29578
main(){
	double v1, acos_val;
	for (v1 = -1.0; v1 <= 1.0; v1 += 0.1){
		acos_val = acos(v1)*RadianToDegree;
		if (errno != EDOM)
			printf("Arc cosine (%4.1f) = %3.0f\n", v1, acos_val);
		else
			printf("Input error");
	}
}

/* asctime.c */
#include <time.h>
#include <stdlib.h>
main(){
	struct tm *currenttime;
	time_t bintime;
	time(&bintime);
	currenttime=localtime(&bintime);
	printf("目前時間: %s\n", asctime(currenttime));
}

/* asin.c */
#include <math.h>
#include <errno.h>
#include <stdlib.h>
#define  RadianToDegree 57.29578
main(){
	double v1, asin_val;
	for (v1 = -1.0; v1 <= 1.0; v1 += 0.1){
		asin_val = asin(v1)*RadianToDegree;
		if (errno != EDOM)
			printf("Arc sin(%4.1f) = %3.0f\n", v1, asin_val);
		else
			printf("Input error");
	}
}

/* assert.c */
#include <assert.h>
#include <stdlib.h>

main(){
	int x, y;
	printf("Please input two integer for division: ");
	scanf("%d %d", &x, &y);

	/*  Is the divisor zero?   */
	assert(y != 0);			// if(y==0) exit(0);
	/*  Print the result.  */
	printf("%d / %d = %d\n", x, y, x/y);
}

/* atan.c */
#include <math.h>
#include <errno.h>
#include <stdlib.h>
#define  RadianToDegree 57.29578
main(){
	double v1, atan_val;
	for (v1 = -1.0; v1 <= 1.0; v1 += 0.1){
		atan_val = atan(v1)*RadianToDegree;
		if (errno != EDOM)
			printf("Arc tangent(%4.1f) = %3.0f\n", v1, atan_val);
		else
			printf("Input error");
	}
}

/* atan2.c */
#include <math.h>
#include <errno.h>
#include <stdlib.h>
#define  RadianToDegree 57.29578

main(){
	char s[10];
	double y, x, atan2_val;
	printf("輸入y與x，然後計算atan2\n");
	printf("y: ");
	gets(s);
	y = atof(s);

	printf("x: ");
	gets(s);
	x = atof(s);

	atan2_val = atan2(y, x)*RadianToDegree;
	if (errno != EDOM)
		printf("atan2(%.0f/%.0f) = %.2f\n", y, x, atan2_val);
	else
		printf("Input error");
}

/* atexit.c */
/* Function Prototyping */
void Fun1();
void Fun2();
void Fun3();
void Fun4();
void Fun5();
void Fun6();

main(){
	printf("Now recording Function 1..\n");	atexit(Fun1);
	printf("Now recording Function 2..\n");	atexit(Fun2);
	printf("Now recording Function 3..\n");	atexit(Fun3);
	printf("Now recording Function 4..\n");	atexit(Fun4);
	printf("Now recording Function 5..\n");	atexit(Fun5);
	printf("Now recording Function 6..\n");	atexit(Fun6);
	printf("The main program stops!\n");
}

/*  Function 1.  */
void Fun1(){
	printf("Function 1 is called.\n");
}
/*  Function 2.  */
void Fun2(){
	printf("Function 2 is called.\n");
}
/*  Function 3.  */
void Fun3(){
	printf("Function 3 is called.\n");
}
/*  Function 4.  */
void Fun4(){
	printf("Function 4 is called.\n");
}
/*  Function 5.  */
void Fun5(){
	printf("Function 5 is called.\n");
}
/*  Function 6.  */
void Fun6(){
	printf("Function 6 is called.\n");
}

/* atof.c 文字轉小數 */
#include <stdlib.h>
main(){
	char s[10];
	double v;

	printf("請輸入一浮點數的字串 (e.g.123.456): ");
	gets(s);
	v = atof(s);
	printf("轉換後的數值為 %g\n", v);
}

/* atoi.c 文字轉整數 */
#include <stdlib.h>
main(){
	char s[10];
	int v;

	printf("請輸入一整數字串 (e.g.123.456e2): ");
	gets(s);
	v = atoi(s);
	printf("轉後的整數為 %d\n", v);
}

/* atol.c 文字轉長整數 */
#include <stdlib.h>
main(){
	char s[10];
	long v;

	printf("請輸入一長整數字串 (e.g.123.456e2): ");
	gets(s);
	v = atol(s);
	printf("轉後的整數為 %ld\n",v);
}

/* bsearch.c 二分搜尋 */
#include <stdlib.h>
#define NUM(arr) sizeof(arr)/sizeof(arr[0])

int intarr[]={11,15,17,122,143,144,199,200,395,466,578,999};

int compare(const int *elem1, const int *elem2){
	return(*elem1 - *elem2);
}

int check(int key){
	int *ans;
	ans = bsearch(&key, intarr, NUM(intarr), sizeof(int), compare);
	return (ans != NULL);
}

main(){
	int inputint=0;
	printf("This is a game to test your luck.\n");
	printf("Please input one integer: ");
	scanf("%d", &inputint);
	if (check(inputint))
		printf("Bingo! %d is in the internal array.\n", inputint);
	else
		printf("%d isn't in the internal array.\n", inputint);
}

/* calloc.c */
#include <stdlib.h>
#include <stdlib.h>
main(){
	char *Buff;
	/*  Buffer allocated.  */
	Buff = (char *)calloc(80, sizeof(char));

	printf("Buffer allocated.\n");
	printf("Please input a string: ");
	gets(Buff);
	printf("The string which you input is : \"%s\".\n", Buff);
}

/* ceil.c 上捨入 */
#include <math.h>
#include <stdlib.h>
main(){
	double v1, ceil_val;
	printf("請輸入一浮點數: ");
	scanf("%lf", &v1);
	ceil_val = ceil(v1);
	printf("ceiling of %.2f = %.2f\n", v1, ceil_val);
}

/* char_type_test.c */
#include <string.h>
#include <ctype.h>
#include <stdlib.h>

/* Define a table of function names and numbers */
typedef struct TABLE{
	char functionname[16];
	int funcnum;
}FUNC_TABLE;

#define CNTRL 0
#define DIGIT 1
#define GRAPH 2
#define LOWER 3
#define PRINT 4
#define PUNCT 5
#define SPACE 6
#define UPPER 7
#define XDIGIT 8

/* Now declare the tabel and initialize it */
static FUNC_TABLE isfuncs[9] = {
	"iscntrl",CNTRL,"isdigit",DIGIT,
	"isgraph",GRAPH,"islower",LOWER,
	"isprint",PRINT,"ispunct",PUNCT,
	"isspace",SPACE,"isupper",UPPER,
	"isxdigit",XDIGIT
};
static int numfunc = sizeof(isfuncs)/sizeof(FUNC_TABLE);

main(){
	int ch, count, i, test_result;
	int mark=0x2a;	/* to mark characters */
	char input_func_name[9];
	printf("Enter function's name of special attribute ASCII"
		" character\nthat you want to find out: ");
	gets(input_func_name);
	/* Search table for function name and pointer */
	for (i=0;i<numfunc;i++) {
		if (strcmp(input_func_name,isfuncs[i].functionname)==0) {
			break;
		}
	}
	if (i>=numfunc) {
		printf("unknown functions:%s\n",input_func_name);
		exit(0);
	}
	/* Now go over entire ASCII table and mark the */
	/* characters that satisfy requested test      */
	printf("Those marked with a %c satisfy %s\n"
		   ,mark,input_func_name);
	for (count=0,ch=0;ch<=0x7f;ch++) {
		printf("%#04x ",ch);
		/* Print character -- if printable */
		if (isprint(ch)) {
			printf(" %c",ch);
		}
		else {
			printf("  ");
		}
		/* Perform the test and put a mark if test succeeds */
		switch (isfuncs[i].funcnum) {
		case CNTRL:
			test_result=iscntrl(ch);
			break;
		case DIGIT:
			test_result=isdigit(ch);
			break;
		case GRAPH:
			test_result=isgraph(ch);
			break;
		case LOWER:
			test_result=islower(ch);
			break;
		case PRINT:
			test_result=isprint(ch);
			break;
		case PUNCT:
			test_result=ispunct(ch);
			break;
		case SPACE:
			test_result=isspace(ch);
			break;
		case UPPER:
			test_result=isupper(ch);
			break;
		case XDIGIT:
			test_result=isxdigit(ch);
			break;
		}
		if (test_result!=0) {
			printf("%c ",mark);
		}
		else {
			printf("  ",ch);
		}
		count++;
		if (count==6) {
			printf("\n");
			count=0;
		}
	}
	printf("\n");
}

/* clearerr.c */
#include <stdlib.h>
main(){
	FILE *fp;
	char fname[80];

	printf("Enter an existing file name:");
	gets(fname);

	/* Open the file */
	if ((fp = fopen(fname, "r")) == NULL) {
		printf("Failed to open : %s\n", fname);
	}

	/* Try to write a message to the file... */
	printf("Attempt to write a message to the file...\n");
	fputs("Test string", fp);

	if (ferror(fp) != 0) {
		printf("Error occured!\n");
		clearerr(fp); /* Clear the error */
		printf("Error cleared.\n");
	}
}

/* clock.c */
#include <stdlib.h>
#include <time.h>
main(){
	int i,count=500000000;
	double a,b,c,d;
	unsigned t_used;
	clock_t t_start,t_end;
	t_start=clock();
	for (i=0;i<count;i++) {
		a=(double)(i-1);
		b=(double)(i+1);
		c=(double)(i*1);
		d=a*b-c;
	}
	t_end=clock();
	t_used=(t_end-t_start)/CLK_TCK;
	printf("500000000 迴圈需要 %u 秒\n",t_used);
}

/* cos.c */
#include <math.h>
#include <stdlib.h>
#define  RadianToDegree 57.29578

main(){
	double v1, cos_val;
	for (v1 = 0; v1 <= 360; v1 += 30){
		cos_val = cos(v1/RadianToDegree);
		printf("Cosine (%3.0f) = %5.1f\n", v1, cos_val);
	}
}

/* cosh.c */
#include <math.h>
#include <stdlib.h>
#define  RadianToDegree 57.29578

main(){
	double v1, cosh_val;

	for (v1=0; v1<=360; v1+=30){
		cosh_val = cosh(v1/RadianToDegree);
		printf("Hyperbolic cosine (%3.0f) = %6.2f\n", v1, cosh_val);
	}
}

/* ctime.c 日期/時間 */
#include <stdlib.h>
#include <time.h>
main(){
	time_t bintime;
	bintime=time(NULL);
	printf("Today's date and time: %s\n",ctime(&bintime));
}

/* difftime.c 時間差 */
#include <stdlib.h>
#include <time.h>
main(){
	time_t t_start,t_end;
	int i;

	t_start=time(NULL);
	_sleep(5000);
	t_end=time(NULL);
	printf("The program ran in %6.2f seconds\n",
		difftime(t_end, t_start));
}

/* div.c */
#include <stdlib.h>
main(){
	char s[10];
	int numer, denom;
	div_t div_result;
	printf("請輸入分子: ");
	gets(s);
	numer = atoi(s);
	printf("請輸入分母: ");
	gets(s);
	denom = atoi(s);
	div_result=div(numer, denom);
	printf("%d/%d\n", numer, denom);
	printf("商 = %d\n餘數 = %d\n", div_result.quot, div_result.rem);
}

/* exit.c */
#include <stdlib.h>
void fun();

main(){
	FILE *fp;
	char FileName[81];
	atexit(fun);

	printf("Please input an existing file name: ");
	gets(FileName);

	/* Open file */
	if ((fp = fopen(FileName, "w+")) == NULL) {
		printf("File not found!\a\n");
		abort();
	}

	/*  Output data to buffer.  */
	fprintf(fp, "The function \"exit\" will flush the buffers!\n");
	fprintf(fp, "So, you can see this message in this file!\n");
	printf("The function \"exit\" flushed the buffers!\n");
	exit(0);
}

void fun(){
	printf( "The function \"fun\" is called " );
	printf( "when the main program stops!\n" );
}

/* exp.c (e^x)*/
#include <math.h>
#include <stdlib.h>
main(){
	char s[10];
	double v0, v1;
	printf("請輸入一整數: ");
	gets(s);
	v0 = atof(s);
	v1 = exp(v0);
	printf("exp(%.1f) = %.2f\n", v0, v1);
}

/* fabs.c 絕對值 */
#include <math.h>
#include <stdlib.h>
main(){
	char s[10];
	double v0, v1;
	printf("請輸入一浮點數: ");
	gets(s);
	v0 = atof(s);
	v1 = fabs(v0);
	printf("此數的絕對值為 %g\n", v1);
}

/* fclose.c */
#include <stdlib.h>
main(){
	FILE *fp;
	char s[81];

	if ((fp = fopen("fclose.c", "r")) == NULL) {
		printf("File open failure 失敗.\n");
	}

	printf("=== Top of File ===\n");
	while (fgets(s, 80, fp) != NULL)
		printf(s);

	fclose(fp);
	printf("=== File is closed. ===\n");
}

/* feof.c */
#include <stdlib.h>
main(){
	FILE *fp;
	char s[81];

	if ((fp = fopen("feof.c", "r")) == NULL) {
		printf("Cannot open feof.c\n");
		exit(0);
	}

	printf("=== Top of File ===\n");
	while (fgets(s, 80, fp))
		printf(s);

	if (feof(fp) != 0)
		printf("=== End of File ===\n");
	else
		printf("\nFailed to read file.");
}

/* ferror.c */
#include <stdlib.h>
main(){
	FILE *fp;

	fp = fopen("test", "w");

	/* force to occur an error condition */
	getc(fp);

	if (ferror(fp) != 0) {
		/* Display an error message */
		printf("Error to read from file 'test'\n");

		/* Cleear error state */
		clearerr(fp);
	}
	fclose(fp);
}

/* fflush.c */
#include <stdlib.h>
main(){
	FILE *fp;
	int  result;

	fp = fopen("test", "w");

	printf("Write message 'This is a test.' to file...\n");
	fputs("This is a test.", fp);

	printf("Flush the data to file 'test'....\n");
	result = fflush(fp);

	if (result == 0)
		printf("File was successfully flushed.\n");
	else
		printf("Failed to flush the file.\n");
	fclose(fp);
}

/* fgetc.c */
#include <stdlib.h>
main(){
	FILE *fp;
	int  ch;

	if ((fp = fopen("fgetc.c", "r")) == NULL) {
		printf("Cannot open file fgetc.c\n");
		exit(0);
	}

	printf("=== Content of file fgetc.c: ===\n");
	while ((ch = fgetc(fp)) != EOF)
		putchar(ch);

	printf("=== End of File fgetc.c ===\n");
	fclose(fp);
}

/* fgetpos.c */
#include <stdlib.h>
main(){
	FILE   *fp;
	fpos_t curpos;

	if ((fp = fopen("fgetpos.bak", "w")) == NULL) {
		printf("Error to create file.\n");
		exit(0);
	}

	/* Get current file pointer */
	if (fgetpos(fp, &curpos) == 0)
		printf("Current file pointer is at %d\n", curpos);
	else
		printf("Error occured!\n");

	printf("Now write the message 'This is a test.\\n' to file...\n");

	/* Write message to the file */
	fputs("This is a test.\n", fp);

	/* Get current file pointer */
	fgetpos(fp, &curpos);
	printf("Current file pointer is at %d\n", curpos);
	fclose(fp);
}

/* fgets.c */
#include <stdlib.h>
main(){
	FILE *fp;
	char s[81];

	if ((fp = fopen("fgets.c", "r")) == NULL) {
		printf("File open failure 失敗.\n");
		exit(0);
	}

	printf("=== Content of the file fgets.c ===\n");
	while (fgets(s, 81, fp) != NULL)
		printf(s);

	fclose(fp);
	printf("=== End of File ===\n");
}

/* floor.c 下捨入 */
#include <math.h>
#include <stdlib.h>
main(){
	char s[10];
	double v1, floor_val;
	printf("請輸入一浮點數: ");
	gets(s);
	v1 = atof(s);
	floor_val = floor(v1);
	printf("floor(%g) = %g\n", v1, floor_val);
}

/* fmod.c */
#include <math.h>
#include <stdlib.h>
main(){
	char s[10];
	double numerator, denominator, remainder;	// 分子,分母,餘數
	printf("請輸入分子: ");
	gets(s);
	numerator = atof(s);	// 分子
	printf("請輸入分母: ");
	gets(s);
	denominator = atof(s);	// 分母
	remainder = fmod(numerator, denominator);
	printf("(%g/%g)的餘數 = %g\n", numerator, denominator, remainder);
}

/* fopen0.c */
#include <stdlib.h>
#include <string.h>
main(){
	FILE *fp, *fp2;
	char s[81];

	if ((fp = fopen("fopen0.c", "r")) == NULL) {
		printf("File 'fopen0.c' open failure 失敗.\n");
		exit(0);
	}

	if ((fp2 = fopen("fopen0.bak", "w")) == NULL) {
		printf("Cannot create 'fopen0.bak'.\n");
		exit(0);
	}

	printf("\nCopying file fopen0.c to fopen0.bak......\n");
	while (fgets(s, 81, fp) != NULL)
		fputs(s, fp2);

	fclose(fp);
	fclose(fp2);

	printf("\nCompleted.\n");
}

/* fopen1.c */
#include <stdlib.h>
main(){
	FILE *fp;
	char s[17];
	int  length;
	int  i;

	if ((fp = fopen("fopen0.c", "rb")) == NULL) {
		printf("Cannot not open file 'fopen.c'.\n");
		exit(0);
	}

	while ((length = fread(s, 1, 16, fp)) != 0) {
		for (i = 0; i < 16; i++)
			if (i < length)
				printf("%02X ", s[i]);
			else
				printf("   ");

		printf("   ");

		for (i = 0; i < length; i++)
			printf("%c", (s[i] < 32) ? '.' : s[i]);

		printf("\n");
	}
}

/* fprintf.c */
#include <stdlib.h>
main(){
	FILE  *fp, *fp2;
	int   i    = 200;
	char  ch   = 'A';
	float f    = 3.1415f;
	char  *str = "This is a test.";
	char s[81];

	if ((fp2 = fopen("test", "w")) == NULL) {
		printf("File create failure 建立失敗.\n");
		exit(0);
	}

	printf("write '%d', '%c', '%f', and '%s' to file 'test'...\n",
		   i, ch, f, str);
	fprintf(fp2, "%d, %c, %f, %s", i, ch, f, str);
	printf("Close file 'test'.\n");
	fclose(fp2);

	printf("Reopen file 'test' for reading...\n");
	fp = fopen("test", "r");
	printf("The results of last writing...\n");
	fgets(s, 81, fp);
	puts(s);
	fclose(fp);
}

/* fputc.c */
#include <stdlib.h>
main(){
	char *str = "This is a test.";
	int  i;

	for (i = 0; str[i] != '\0'; i++)
		fputc(str[i], stdout);
	printf("\n");
}

/* fputs.c */
#include <stdlib.h>
main(){
	char *str = "This is a test.";

	fputs(str, stdout);
	printf("\n");
}

/* fread.c */
main(){
	FILE *fp;
	char s[1024]="";

	if ((fp = fopen("fread.c", "rb")) == NULL) {
		printf("Cannot open file 'fread.c'.\n");
		exit(0);
	}

	printf("First 1024 characters in file 'fread.c'...\n");
	fread(s, sizeof(char), 1024, fp);
	/* Add a null character to the end oif string buffer */
	s[1023] = '\0';
	printf("%s", s);
	fclose(fp);
}

/* free.c 放 */
#include <stdlib.h>
#include <stdlib.h>
main(){
	char *s;

	if ( ( s = ( char * )malloc( 256 ) ) == NULL ){
		printf( "Memory allocated failed!\a\n" );
		abort();
	}
	printf( "Memory allocated!\n" );
	printf( "Please input a string: " );
	gets(s);
	printf( "This string is \"%s\".\n", s );

	free(s);
	printf( "Memory released!\n" );
}

/* freopen.c */
#include <stdlib.h>

main(){
	FILE *fp;
	char s[81];

	/* Redirect screen to a file */
	if (freopen("screen.out", "w", stdin) == NULL) {
		fprintf(stderr, "Error to redirecting stdout.\n");
		exit(0);
	}

	printf("Write message....\n");
	/* This message will go to a file. */
	fprintf(stdin, "This is a test to screen.out file...\n");

	/* Close the standard output fp */
	printf("-----\n");
	printf("close the file\n");
	fclose(stdin);
	printf("-----\n\n");

	/* Get the message from screen.out file */
	fp = fopen("screen.out", "r");
	fgets(s, 81, fp);

	printf("The message you wrote to print is :\n");
	printf("%s", s);
}

/* frexp.c */
#include <math.h>
#include <stdlib.h>
main(){
	int exponent;
	double number, mantissa;
	printf("請輸入一浮點數: ");
	scanf("%lf", &number);
	mantissa = frexp(number, &exponent);
	printf("%g 是 %g 乘以 2 的 %d 次方\n", number, mantissa, exponent);
}

/* fscanf.c */
#include <stdlib.h>
main(){
	FILE *fp;
	char token[81];

	if ((fp = fopen("fscanf.c", "r")) == NULL) {
		printf("Cannot open file 'fscanf.c'.\n");
		exit(0);
	}

	printf("All tokens in the file 'fscanf.c' are:\n");

	while (fscanf(fp, "%s", token) != EOF)
		printf("%-20s", token);
	fclose(fp);
}

/* fseek.c 移至 */
#include <stdlib.h>
long filesize(char *filename);
main(){
	printf("The size of file %s is %ld\n",
		"fseek.c", filesize("fseek.c"));
}

long filesize(char *filename){
	FILE *fp;
	long length;

	if ((fp = fopen(filename, "rb")) == NULL) {
		printf("File %s doesn't exist.\n", filename);
		exit(0);
	}

	// 0:SEEK_SET,1:SEEK_CUR,2:SEEK_END
	/* Move file indicator to the end of the file */
	fseek(fp, 0L, SEEK_END);

	/* get the length of the file */
	length = ftell(fp);
	return length;
}

/* fsetpos.c */
#include <stdlib.h>
main(){
	FILE   *fp;
	fpos_t curpos;
	char   s[20];

	if ((fp = fopen("test", "w")) == NULL) {
		printf("Cannot create file 'test'.\n");
		exit(0);
	}

	printf("Get current file location...\n");
	fgetpos(fp, &curpos);
	printf("Write message 'This is a test 1' to file 'test'...\n");
	fputs("This is a test 1", fp);

	printf("Move file indicator to last file location...\n");
	if (fsetpos(fp, &curpos) != 0) {
		printf("Cannot setting file pointer.\n");
		exit(0);
	}

	printf("Write message 'THIS IS A TEST 2' to file 'test'...\n");
	fputs("THIS IS A TSET 2", fp);

	fclose(fp);
	fp = fopen("test", "r");

	printf("Content of the file 'test':\n");
	fgets(s, 20, fp);
	printf("%s\n",s);
	fclose(fp);
}

/* ftell.c 目前位置 */
main(){
	FILE *fp;
	if ((fp = fopen("test", "w")) == NULL) {
		printf("Cannot create file 'test'\n'");
		exit(0);
	}

	printf("Write message 'This is a test.' to file...\n");
	fprintf(fp, "This is a test.");
	printf("The file pointer is at byte %ld\n", ftell(fp));
	fclose(fp);
}

/* fwrite.c */
#include <string.h>
struct stdnt {
	char name[10];
	int  score;
};

main(){
	FILE *fp;
	struct stdnt student;

	strcpy(student.name, "Jerry");
	student.score = 80;

	if ((fp = fopen("test", "r+b")) == NULL) {
		printf("Cannot create file 'test'.\n");
		exit(0);
	}

	printf("Write the record to file 'test'...\n");
	fwrite(&student, sizeof(struct stdnt), 1, fp);

	fseek(fp, 0L, SEEK_SET);
	fread(&student, sizeof(struct stdnt), 1, fp);
	printf("The contents of the file 'test' are...\n");
	printf("Student name: %s\n", student.name);
	printf("Student score: %d\n", student.score);
	fclose(fp);
}

/* getc.c */
#include <stdlib.h>
main(){
	FILE *fp;
	int  ch;

	if ((fp = fopen("getc.c", "r")) == NULL) {
		printf("Cannot open file getc.c\n");
		exit(0);
	}

	printf("=== Content of file getc.c: ===\n");
	while ((ch = getc(fp)) != EOF)
		putchar(ch);

	printf("=== End of File getc.c ===\n");
	fclose(fp);
}

/* getchar.c */
#include <stdlib.h>
main(){
	char s[81];
	int  ch;
	int  i;

	printf("Please enter a line:\n");
	for (i = 0; i < 80 && (ch = getchar()) != '\n'; i++)
		s[i] = ch;

	s[i] = '\0';
	printf("The line you entered is: %s\n", s);
}

/* getenv.c */
#include <stdlib.h>
main(){
	printf("Current path=%s\n", getenv("PATH"));
}

/* gets.c */
#include <stdlib.h>
main(){
	char s[81];

	printf("Please enter a line:\n");
	gets(s);
	printf("The line you entered is: %s\n", s);
}

/* gmtime.c */
#include <time.h>
#include <stdlib.h>

main(){
	time_t current_time;
	struct tm *current_tm;
	time(&current_time);
	current_tm=gmtime(&current_time);
	printf("Greenwich Mean Time = %s\n", asctime(current_tm));
}

/* isalnum.c 字母或數字 */
#include <ctype.h>
#include <stdlib.h>
main(){
	int c, count;
	printf("Alphnumeric:\n\n");
	for (count=0,c=0;c<=0x7f;c++) {
		if (isprint(c)&&(isalnum(c) != 0)) {
			printf(" %#05d ", c);
			printf(" %c ", c);
			count++;
		}

		if (count == 6) {
			printf("\n");
			count = 0;
		}
	}
	printf("\n");
}

/* isalpha.c 字母 */
#include <ctype.h>
#include <stdlib.h>
main(){
	int c, count;
	printf("Alphabetic:\n\n");
	for (count=0,c=0;c<=0x7f;c++) {
		if (isprint(c) && (isalpha(c) != 0)) {
			printf(" %#05d ", c);
			printf(" %c ", c);
			count++;
		}

		if (count == 6) {
			printf("\n");
			count = 0;
		}
	}
	printf("\n");
}

/* labs.c */
#include <stdlib.h>
#include <stdlib.h>
main(){
	long v1,v2;
	printf("請輸入一長整數: ");
	scanf("%ld", &v1);
	v2 = labs(v1);
	printf("此數的絕對值為 %ld\n", v2);
}

/* ldexp.c */
#include <math.h>
#include <stdlib.h>
main(){
	double mantissa, ldexp_val;
	int exponent;
	printf("計算 (mantissa*2^exp)\n");
	printf("Mantissa: ");
	gets(s);
	mantissa = atof(s);
	printf("Exponent: ");
	gets(s);
	exponent= atoi(s);
	ldexp_val = ldexp(mantissa, exponent);
	printf("%g 乘以 2 的 %d 次方 = %g\n", mantissa, exponent, ldexp_val);
}

/* ldiv.c */
#include <stdlib.h>
main(){
	long numer, denom;
	ldiv_t ldiv_result;
	printf("請輸入分子: ");
	scanf("%d", &numer);
	printf("請輸入分母: ");
	scanf("%d", &denom);
	ldiv_result = ldiv(numer, denom);
	printf("%ld/%ld\n", numer,denom);
	printf("商 = %ld\n餘數 = %ld\n", ldiv_result.quot, ldiv_result.rem);
}

/* localeco.c */
#include <locale.h>
main(){
	struct lconv *Locale ;
	Locale = localeconv();
	printf("Locale informations :\n");
	printf("Decimal Point          = %s\n", Locale->decimal_point );
	printf("Thousands Separator    = %s\n", Locale->thousands_sep );
	printf("Grouping               = %s\n", Locale->grouping );
	printf("Positive sign position = %d\n", Locale->p_sign_posn );
	printf("Negative sign position = %d\n", Locale->n_sign_posn );
}

/* localtim.c */
#include <time.h>
#include <stdlib.h>
main(){
	time_t current_time;
	struct tm *current_tm;
	time(&current_time);
	printf("1970年1月1日00:00:00至現在經過 %ld 秒 \n", current_time);
	current_tm=localtime(&current_time);
	printf("Local Time = %s\n",asctime(current_tm));
}

/* log.c */
#include <math.h>
#include <stdlib.h>
#include <errno.h>
main(){
	double x, log_val;
	printf("計算某數的自然對數值\n");
	printf("請輸入一數值: ");
	scanf("%lf", &x);
	log_val = log(x);
	if (errno != EDOM && errno != ERANGE) {
		printf("log(%g)=%g\n", x, log_val);
	}
}

/* log10.c */
#include <math.h>
#include <stdlib.h>
#include <errno.h>

main(){
	double x, log10_val;
	printf("計算某數以10為底的對數值\n");
	printf("請輸入一數值: ");
	scanf("%lf", &x);
	log10_val = log10(x);
	if (errno != EDOM && errno != ERANGE) {
		printf("log10(%g)=%g\n", x, log10_val);
	}
}

/* longjmp.c */
#include <stdlib.h>
#include <setjmp.h>

jmp_buf RetBuff;
void Call_jmp(jmp_buf);

main(){
	int v1;

	printf("Set up CallFunction status by calling the ");
	printf("function \"setjmp\"..\n");

	v1 = setjmp(RetBuff);
	printf("\n.......Value is %d...\n", v1);
	if (v1 !=0) {
		printf("CallFunction by call the function ");
		printf("\"longjmp\".\n");
		exit(0);
	}

	printf("Now calling the function \"longjmp\"..\n");
	Call_jmp(RetBuff);
}

/*  Function "Call_jmp" will call "longjmp"  */
void Call_jmp(jmp_buf RetBuff){
	longjmp(RetBuff, 1);
}

/* malloc.c */
#include <stdlib.h>
#include <stdlib.h>
main(){
	char *MemBlk;

	if ((MemBlk = (char *)malloc(256)) == NULL){
		printf("Memory allocated failed!\a\n");
		abort();
	}
	printf("Memory allocated!\n");
	printf("Please input a string: ");
	gets(MemBlk);

	printf("This string is \"%s\".\n", MemBlk);
	free(MemBlk);
	printf("Memory has been collected!\n");
}

/* memchr.c */
#include <string.h>
main(){
	char s[81] = {"Apple computer"};
	memchr(s, 'c', 80);

	printf("The first character address is %#x\n", s);
	printf("The address of 'c' is %#x\n", memchr(s, 'c', 80));
}

/* memcmp.c */
#include <string.h>
main(){
	char s1[] = "Microsoft Visual C++ 2008", s2[] = "ANSI C/C++";
	int RetValue;

	printf("First string is \"%s\".\n", s1);
	printf("Second string is \"%s\".\n", s2);
	RetValue = memcmp(s1, s2, 7);

	if (!RetValue)
		printf("First string = Second string.\n");
	else
		if (RetValue < 0)
			printf("First string < Second string.\n");
		else
			printf("First string > Second string.\n");
}

/* memcpy.c */
#include <string.h>
main(){
	char source[81] = "ANSI C Bible";
	char dest[81] = "dummy";

	printf("Before copy:\n");
	printf("  source      = \"%s\".\n", source);
	printf("  destination = \"%s\".\n", dest);

	memcpy(dest, source, 81);
	printf("After copy:\n");
	printf("  source      = \"%s\".\n", source);
	printf("  destination = \"%s\".\n", dest);
}

/* memmove.c */
#include <string.h>
main(){
	char s[80] = "ANSI C Bible";

	printf("Before move:\n");
	printf("  s = \"%s\".\n", s);
	memmove(s + 5, s, sizeof(s));
	printf("After move:\n");
	printf("  s = \"%s\".\n", s);
}

/* memset.c */
#include <string.h>
main(){
	char s[11] = "computer";

	printf("Before set:\n");
	printf("  s = \"%s\".\n", s);
	memset(s, 'C', 10);
	s[10] = '\0';
	printf("After set:\n");
	printf("  s = \"%s\".\n", s);
}

/* mktime.c */
#include <stdlib.h>
#include <time.h>

char *wday[] = {"Sunday", "Monday", "Tuesday", "Wednesday",
		"Thursday", "Friday", "Saturday", "Unknown"};

main(){
	struct tm time_check;
	int year, month, day;
	printf("Year:  ");	scanf("%d", &year);
	printf("Month: ");	scanf("%d", &month);
	printf("Day:   ");	scanf("%d", &day);
	time_check.tm_year = year - 1900;
	time_check.tm_mon  = month - 1;
	time_check.tm_mday = day;
	time_check.tm_hour = 0;
	time_check.tm_min  = 0;
	time_check.tm_sec  = 1;
	time_check.tm_isdst = -1;
	if (mktime(&time_check) == -1)
		time_check.tm_wday = 7;
	printf("Today is  %s\n", wday[time_check.tm_wday]);
}

/* modf.c */
#include <math.h>
#include <stdlib.h>
main(){
	double v, intpart, fract;
	printf("請輸入一浮點數: ");
	scanf("%lf", &v);
	fract = modf(v, &intpart);
	printf("%g 的整數部份為 %g, 小數部份為 %g\n" ,v, intpart, fract);
}

/* perror.c */
main(){
	char filename[11];
	FILE *fp;

	tmpnam(filename);
	printf("Attempting to open '%s'...\n", filename);

	if ((fp = fopen(filename, "r")) == NULL)
		perror("Error to open the specified file.\n");
	else {
		printf("File open is successful.\n");
		fclose(fp);
	}
}

/* pow.c */
#include <math.h>
#include <stdlib.h>
main(){
	double x, y, v;

	printf("請輸入兩數，計算 x^y\n");
	printf("X: ");	scanf("%lf", &x);
	printf("Y: ");	scanf("%lf", &y);
	v = pow(x, y);
	printf("%g 的 %g 次方為 %g\n", x, y, v);
}

/* printf.c */
#include <stdlib.h>
main(){
	char *s = "This is a test.";
	int   i = 100;
	float f = 3.1415926f;

	printf("s = %s\n", s);
	printf("Address of msg : %Fp\n", s);
	printf("The first character of msg is : %c\n", s[0]);

	printf("i = %3d  (in decimal 十進)\n", i);
	printf("i = %3o  (in octal   八進)\n", i);
	printf("i = %3x  (in hexadecimal 十六進)\n", i);

	printf("f = %-11f (in the floating point format)\n", f);
	printf("f = %-11e (in the scientific format)\n", f);
}

/* putc.c */
main(){
	char *s = "This is a test.";	// char s[16];
	int  i;
	for (i=0; s[i] != '\0'; i++)
		putc(s[i], stdout);
	printf("\n");
}

/* putchar.c */
main(){
	char *s = "This is a test.";
	int  i;
	for (i=0; s[i] != '\0'; i++)
		putchar(s[i]);
}

/* puts.c */
#include <stdlib.h>
main(){
	char *s = "This is a test.";
	puts(s);
	printf("Over\n");
}

/* qsort.c 快速排序法 */
#include <stdlib.h>
int a[]={999,15,17,143,122,144,578,200,395,466,333,11};

int compare(const int *elem1, const int *elem2){
	return(*elem1 - *elem2);
}

main(){
	int i;
	printf("Source sequence: 排序前\n");
	for (i=0;i<=11;i++)
		printf("%d\n",a[i]);
	qsort((void *)a, 12, sizeof(a[0]), compare);
	printf("\nSorting...\n\n");
	printf("Target sequence: 排序後\n");
	for (i=0;i<=11;i++)
		printf("%d\n",a[i]);
}

/* raise.c */
#include <signal.h>
main(){
	printf("Raise the signal SIGINT..\n");
	raise(SIGINT);
}

/* rand.c */
#include <stdlib.h>
main(){
	int i;
	printf("產生五個隨機rand亂數:\n");
	for (i=0;i<5;i++) {
		printf("%d\n", rand());
	}
}

/* realloc.c */
#include <stdlib.h>
#include <stdlib.h>
main(){
	char *s;

	s = (char *)malloc(81);
	if (s == NULL) {
		printf("Allocated memory failed!\a\n");
		abort();
	}

	printf("Memory allocated.\n");
	printf("Please input a string: ");
	gets(s);
	printf("This string is \"%s\".\n", s);

	/*  Enlarge the memory.  */
	s = (char *)realloc(s, 256);
	if (s == NULL) {
		printf("Memory adjusted failed!\a\n");
		abort();
	}
	printf("Memory adjusted succeed.\n");
	printf("The memory adjusted also contains \"%s\".\n", s);
	free(s);
}

/* remove.c */
#include <errno.h>
main(){
	char filename[80];

	printf("Please enter a filename to delete: ");
	gets(filename);

	if (remove(filename) == 0)
		printf("File deleted Successfully: %s\n", filename);
	else{
		switch (errno){
		case ENOENT:
			printf("Cannot find file: %s\n", filename);
			break;
		case EACCES:
			printf("Permission denied.\n");
			break;
		default    :
			printf("Errno : %d\n", errno);
		}
	}
}

/* rename.c 改名 */
#include <io.h>
#include <stdlib.h>
#include <errno.h>
main(){
	char oldname[80], newname[80];

	printf("Please enter a filename to rename: ");
	gets(oldname);
	/* Checks for file existence */
	if (access(oldname, 0) != 0) {
		printf("File: %s doesn't exist.\n", oldname);
		exit(0);
	}

	printf("Rename %s as: ", oldname);
	gets(newname);
	/* Checks for file existence */
	if (access(newname, 0) == 0) {
		printf("File : %s already exists 存在.\n", newname);
		exit(0);
	}

	if (rename(oldname, newname) == 0)
		printf("Successfully renamed %s as %s\n", oldname, newname);
	else{
		switch (errno) {
		case ENOENT :
			printf("No such file 檔案不存在.\n");
			break;
		case EACCES :
			printf("Permission denied 授權被拒.\n");
			break;
		default     :
			printf("Error no: %d\n", errno);
		}
	}
}

/* rewind.c 回起點 */
#include <stdlib.h>
main(){
	FILE *fp;
	char s[31];
	char *msg1 = "This is the message 1.";
	char *msg2 = "This is the message 2.";

	if ((fp = fopen("test", "w+")) == NULL) {
		printf("Cannot create 建立 file 'test'.\n");
		exit(0);
	}

	printf("Write message 1 '%s' to file 'test'...\n", msg1);
	fprintf(fp , msg1);

	printf("Rewind the file pointer to the beginning of the file...\n");
	rewind(fp);

	printf("Write message 2 '%s' to file 'test'...\n", msg2);
	fprintf(fp , msg2);

	rewind(fp);
	printf("The last content of file is:\n");
	fgets(s, 31, fp);
	printf("%s\n",s);
}

/* scanf.c */
#include <stdlib.h>
main(){
	int   n;
	char  str[80], junk[80];
	float fnumber;
	double dnumber;

	printf("Enter an integer: ");
	scanf("%d", &n);
	printf("The integer you entered is:\n");
	printf("  %4d: in decimal    \n", n);	// 十進
	printf("  %4x: in hexadecimal\n", n);	// 十六進
	printf("  %4o: in octal    \n\n", n);	// 八進

	gets(junk);	/* 吃掉不必要的輸入 */
	printf("Enter a floating point number: ");
	scanf("%f", &fnumber);
	printf("The floating point number you entered is %f\n\n", fnumber);
	gets(junk);	/* 吃掉不必要的輸入 */
	printf("Enter a double precision floating point number: ");
	scanf("%lf", &dnumber);
	printf("The double precision floating point number you entered "
		"is %f\n\n", dnumber);
	gets(junk);	/* 吃掉不必要的輸入 */
	printf("Enter 5 characters: ");
	scanf("%5c", str);
	str[5] = '\0';
	printf("The 5 characters you entered are : %s\n\n", str);
	gets(junk);	/* 吃掉不必要的輸入 */
	printf("Enter a string (Allowed characters: a to z).\n=>");
	scanf("%[a-z]", str);
	gets(junk);	/* 吃掉不必要的輸入 */
	printf("The string you entered is: %s", str);

	printf("\n\nEnter a string (Except characters: a to z).\n=>");
	scanf("%[^a-z]", str);
	gets(junk);	/* 吃掉不必要的輸入 */
	printf("The string you entered is: %s\n", str);
}

/* setbuf.c */
#include <stdlib.h>
main(){
	FILE *fp;
	char s[BUFSIZ];

	printf("Buffer size is %d\n\n", BUFSIZ);
	if ((fp = fopen("setbuf.c", "r")) == NULL) {
		printf("Cannot open file 'test.dat'.\n");
		exit(0);
	}

	setbuf(fp, s);
	printf("Reading a character from file 'test.dat'...\n");
	getc(fp);
	s[BUFSIZ-1] = '\0';

	printf("The content of the buffer: \n");
	printf("%s\n", s);
	fclose(fp);
}

/* setjmp.c */
#include <stdlib.h>
#include <setjmp.h>

jmp_buf RetBuff;
void Call_jmp(jmp_buf );

main(){
	int v;
	printf("Set up CallFunction status by calling the ");
	printf("function \"setjmp\"..\n");

	v = setjmp(RetBuff);
	printf("\n.......Value is %d...\n", v);
	if (v !=0) {
		printf("CallFunction by call the function ");
		printf("\"longjmp\".\n");
		exit(0);
	}

	printf("Now calling the function \"longjmp\"..\n");
	Call_jmp(RetBuff);
}

/*  Function "Call_jmp" will call "longjmp"  */
void Call_jmp(jmp_buf RetBuff){
	longjmp(RetBuff, 1);
}

/* setlocal.c */
#include <locale.h>
main(){
	printf("Old locale was %s\n", setlocale(LC_MONETARY, "C"));
}

/* setvbuf.c */
#include <stdlib.h>
main(){
	FILE *fp;
	char s[400];

	if ((fp = fopen("setvbuf.c", "r")) == NULL) {
		printf("Cannot open file 'setvbuf.c'.\n");
		exit(0);
	}

	if (setvbuf(fp, s, _IOFBF, 399) != 0) {
		printf("Error to set buffer.\n");
		fclose(fp);
		exit(0);
	};

	printf("Reading a character from file 'setvbuf.c'...\n");
	getc(fp);
	printf("The content of the buffer : \n");
	s[399] = '\0';
	puts(s);
	fclose(fp);
}

/* signal.c */
#include <signal.h>
#include <stdlib.h>
void SIGFPE_Handler(int);

main(){
	int a, b;
	if (signal(SIGFPE, SIGFPE_Handler) == SIG_ERR) {
		perror("Set up signal handler error!");
		exit(1);
	}

	printf("If you divided some integer by 0, it can ");
	printf("start \nthe signal handler..\n");
	printf("Now we can input two integers for division.\n");
	scanf("%d %d", &a, &b);
	printf("%d / %d = %d\n", a, b, a/b);
}

/*  The handler for floating-point error.  */
void SIGFPE_Handler(int signum){
	printf("Signal number: %d\n", signum);
	perror("Division error: \a\a\a");
	abort();
}

/* sin.c */
#include <math.h>
#include <stdlib.h>
#define  RadianToDegree 57.29578

main(){
	double v1,sin_val;
	for (v1 = 0; v1<=360; v1+=30){
		sin_val = sin(v1/RadianToDegree);
		printf("Sine (%3g) = %8.2f\n", v1, sin_val);
	}
}

/* sinh.c */
#include <math.h>
#include <stdlib.h>
#define  RadianToDegree 57.29578
main(){
	double v1, sinh_val;
	for (v1 = -1; v1 <= 1; v1 += 0.2){
		sinh_val = sinh(v1/RadianToDegree);
		printf("Hyperbolic sine(%4.1f) = %8.4f\n", v1, sinh_val);
	}
}

/* sprintf.c */
#include <stdlib.h>
main(){
	char s[80];
	sprintf(s, "%d 以十六進位表示為 %#x\n", 100, 100);	// 0x64
	puts(s);
	sprintf(s, "%d 以  八進位表示為 %#o\n", 100, 100);	// 0144
	puts(s);
}

/* sqrt.c 平方根(square root) */
#include <math.h>
#include <stdlib.h>
main(){
	double x, sqrt_val;
	printf("計算某一數值的平方根: \n");
	printf("請輸入一數值: ");
	scanf("%lf", &x);
	sqrt_val = sqrt(x);
	printf("SQRT(%g) = %g\n", x, sqrt_val);
}

/* sqrtl.c */
#include <math.h>
#include <stdlib.h>
main(){
	char *s;
	long double x,v;
	printf("Enter the number that you want to evaluate its square root\n");
	printf("Number:");
	gets(s);
	x=_atold(s);
	v=sqrtl(x);
	printf("SQRT(%Lg) = %Lg\n",x,v);
}

/* srand.c */
#include <stdlib.h>
#include <time.h>
main(){
	int i;
	time_t t;
	srand((unsigned) time(&t));	// srand(time(NULL));
	printf("產生十個 0 到 32767 隨機亂數:\n");
	for (i=0; i<10; i++) {
		printf("%d\n", rand());
	}
}

/* sscanf.c */
#include <stdlib.h>
main(){
	char *raw_data = "Mary 90 88 87 80";
	char name[10];
	int  score[4];

	printf("Raw data : %s\n", raw_data);
	printf("Use sscanf function to scan each of the data item...\n");
	sscanf(raw_data, "%s %d %d %d %d", name, &score[0], &score[1], &score[2], &score[3]);

	printf("Name     : %s\n", name);
	printf("Chinese  : %d\n", score[0]);
	printf("English  : %d\n", score[1]);
	printf("Maths    : %d\n", score[2]);
	printf("Computer : %d\n", score[3]);
}

/* strcat.c 文字合併 */
#include <string.h>
#include <stdlib.h>
main(){
	char s1[20], s2[80];
	printf("Enter two strings which you want to concatenate 合併\n");
	printf("First  string: ");	gets(s1);
	printf("Second string: ");	gets(s2);
	strcat(s1, s2);
	printf("Concatenated string: %s\n", s1);
}

/* strchr.c 字串中找尋字元 */
#include <string.h>
#include <stdlib.h>
main(){
	char s[20], *ptr;
	int c;
	printf("請輸入一字串: ");	gets(s);
	printf("要找尋的字元: ");	scanf("%c",&c);
	printf("陣列第一個元素的位址為 %x \n", s);
	ptr=strchr(s,c);
	if(ptr!=NULL)
		printf("第一次出現字元 %c 是在 %x\n", c, ptr);
	else
		printf("找不到此字元\n", c);
}

/* strcmp.c 文字比較 */
#include <string.h>
#include <stdlib.h>
main(){
	char s1[20], s2[20];
	int n;
	printf("Enter two strings which you want to compare with \n");
	printf("First  string: ");	gets(s1);
	printf("Second string: ");	gets(s2);
	n=strcmp(s1,s2);
	if (n>0)
		printf("%s > %s", s1, s2);
	else if (n<0)
		printf("%s < %s", s1, s2);
	else
		printf("%s = %s", s1, s2);
	printf("\n");
}

/* strcoll.c */
#include <string.h>
#include <stdlib.h>
main(){
	char s1[20],s2[20];
	int n;
	printf("Enter two strings which you want to compare with\n");
	printf("First  string: ");	gets(s1);
	printf("Second string: ");	gets(s2);
	n=strcoll(s1,s2);
	if (n>0)
		printf("%s > %s", s1, s2);
	else if (n<0)
		printf("%s < %s", s1, s2);
	else
		printf("%s = %s", s1, s2);
	printf("\n");
}

/* strcpy.c 文字複製 */
#include <string.h>
#include <stdlib.h>
main(){
	char s1[80], s2[80];
	printf("Enter source string: ");
	gets(s2);
	strcpy(s1, s2);
	printf("Source string is copied to destination string\n");
	printf("Destination string is: %s\n", s1);
}

/* strcspn.c */
#include <string.h>
#include <stdlib.h>
main(){
	char s1[80], s2[80];
	size_t n;
	printf("Enter one string: ");
	gets(s1);
	printf("Enter other string which you want to search: ");
	gets(s2);
	n = strcspn(s1, s2);
	printf("Character strings differ at position: %d\n", n);
}

/* strerror.c */
#include <string.h>
#include <stdlib.h>
main(){
	int i;
	for (i=0; i<=10; i++)
		printf("String error #%2d = %s\n", i, strerror(i));
}

/* strftime.c */
#include <stdlib.h>
#include <time.h>

main(){
	struct tm *currenttime;
	time_t bintime;
	char str[80];
	time(&bintime);
	currenttime=localtime(&bintime);
	strftime(str,80,"Current time: %I:%M:%S %p ", currenttime);
	printf("%s\n",str);
}

/* strlen.c */
#include <string.h>
#include <stdlib.h>
main(){
	char s[20];
	printf("請輸入一字串: ");	gets(s);
	printf("字串 %s 的長度為 %d\n", s, strlen(s));
}

/* strncat.c 文字合併 */
#include <string.h>
#include <stdlib.h>
main(){
	char source[20],dest[20];
	size_t maxlen;
	printf("Enter two strings which you want to concatenate\n");
	printf("First string: ");
	gets(dest);
	printf("Second string: ");
	gets(source);
	printf("How many char of second string want to concatenate: ");
	scanf("%d",&maxlen);
	strncat(dest, source, maxlen);
	printf("Concatenated string: %s", dest);
	printf("\n");
}

/* strncmp.c 比較 */
#include <string.h>
#include <stdlib.h>
main(){
	char s1[20],s2[20];
	size_t maxlen;
	int n;
	printf("輸入要比較的字串\n");
	printf("字串1: ");	gets(s1);
	printf("字串2: ");	gets(s2);
	printf("要比較多少個字元: ");
	scanf("%d", &maxlen);
	n=strncmp(s1, s2, maxlen);

	if (n>0)
		printf("%s > %s", s1, s2);
	else if (n<0)
		printf("%s < %s", s1, s2);
	else
		printf("%s = %s", s1, s2);
	printf("\n");
}

/* strncpy.c 複製 */
#include <string.h>
#include <stdlib.h>
main(){
	char dest[20], source[20];
	size_t maxlen;
	printf("Enter source string: ");
	gets(source);
	printf("How many characters do you want to copy: ");
	scanf("%d", &maxlen);
	strncpy(dest, source, maxlen);
	dest[maxlen]='\0';
	printf("Destination string is: %s\n", dest);
}

/* strnset.c */
#include <string.h>

main(){
	char s[20];
	int ch;
	size_t n;
	printf("Enter one string: ");
	gets(s);
	printf("Enter character you want the string set to: ");
	scanf("%c",&ch);
	printf("How many character you want to set to: ");
	scanf("%d",&n);
	strnset(s,ch,n);
	printf("Converted string is: %s\n",s);
}

/* strpbrk.c */
#include <string.h>
#include <stdlib.h>
main(){
	char s1[20], s2[20], *position;
	printf("Enter one string: ");
	gets(s1);
	printf("Enter one string which you want to search: ");
	gets(s2);
	position = strpbrk(s1, s2);
	printf("The address of s1 is %x\n", s1);
	printf("%s 中的字元出現在: %x\n", s2, position);
}

/* strrchr.c */
#include <string.h>
#include <stdlib.h>
main(){
	char string[20], *ptr;
	int c;
	printf("請輸入一字串: ");
	gets(string);
	printf("輸入要找尋的字元: ");
	scanf("%c",&c);
	printf("陣列第一個元素的位址為 %x \n", string);
	ptr=strrchr(string, c);
	if (ptr)
		printf("最後出現字元 %c 是在 %x\n", c, ptr);
	else
		printf("找不到此字元\n", c);
}

/* strset.c */
#include <string.h>

main(){
	char string[20];
	int ch;
	printf("Enter one string: ");
	gets(string);
	printf("Enter character you want the string set to: ");
	scanf("%c",&ch);
	strset(string,ch);
	printf("Converted string is: %s\n",string);

}

/* strspn.c */
#include <string.h>
#include <stdlib.h>
main(){
	char s1[20], s2[20];
	size_t length;
	printf("Enter one string: ");
	gets(s1);
	printf("Enter other string which you want to search: ");
	gets(s2);
	length = strspn(s1, s2);
	printf("Character where strings different is at position: %d\n", length);
}

/* strstr.c */
#include <string.h>
#include <stdlib.h>
main(){
	char s1[20], s2[20], *ptr;

	printf("請輸入一字串: ");
	gets(s1);
	printf("請輸入要找尋的字串: ");
	gets(s2);
	printf("%s的位址是%x\n", s1, s1);
	ptr = strstr(s1, s2);
	if (ptr)
		printf("%s出現於: %x\n", s2, ptr);
	else
		printf("%s在%s中找不到\n",s2, s1);
}

/* strtod.c */
#include <stdlib.h>

main(){
	char s[20], *stop_at;
	double v;

	printf("請輸入一浮點數字串: ");
	gets(s);
	v=strtod(s, &stop_at);
	printf("轉換後的浮點數為 %g\n", v);
	printf("轉換後停在: %s\n", stop_at);
}

/* strtok.c */
#include <string.h>
#include <stdlib.h>
main(){
	char s1[20], *s2=" ", *ptr;
	printf("請輸入一字串: ");
	gets(s1);
	ptr=strtok(s1, s2);
	while (ptr!=NULL) {
		printf("子字串為: %s\n", ptr);
		ptr=strtok(NULL,s2);
	}
}

/* strtol.c */
#include <stdlib.h>

main(){
	char s[20], *stop_at;
	long v;
	int radix;

	printf("請輸入一長整數字串: ");
	gets(s);
	printf("請入基底數(base): ");
	scanf("%d", &radix);
	v = strtol(s, &stop_at, radix);
	printf("以%2d為基底的數為 %ld\n", radix, v);
	printf("轉換後停在: %s\n", stop_at);
}

/* strtoul.c */
#include <stdlib.h>
#include <limits.h>
#include <math.h>
main(){
	char s[20], *stop_at;
	unsigned long v;
	int radix;

	printf("請輸入一長整數字串: ");
	gets(s);
	printf("請入基底數: ");
	scanf("%d", &radix);
	v = strtol(s, &stop_at, radix);
	printf("以%2d為基底的數為 %lu\n", radix, v);
	printf("轉換後停在: %s\n", stop_at);
}

/* strxfrm.c */
#include <string.h>

main(){
	char dest[20], source[20];
	size_t maxchr, length;
	printf("Enter source string: ");
	gets(source);
	printf("How many characters do you want to copy: ");
	scanf("%d", &maxchr);
	length=strxfrm(dest, source, maxchr);
	dest[maxchr] = '\0';
	printf("Destination string is: %s\n", dest);
}

/* system.c (DOS command) */
#include <stdlib.h>

main(int argc, char *argv[]){
	if (argc != 2) {
		printf("Usage: SYSTEM command\n");
		abort();
	}

	if (system(argv[1]) == -1)
		printf("Command error!\a\n");
}

/* tan.c */
#include <math.h>
#include <stdlib.h>
#define  RadianToDegree 57.29578

main(){

	double v1, tan_val;

	for (v1=0; v1<=360; v1+=15){
		tan_val = tan(v1/RadianToDegree);
		printf("Tangent (%4.1f) = %5.2f\n", v1, tan_val);
	}
}

/* tanh.c */
#include <math.h>
#include <stdlib.h>
#define  RadianToDegree 57.29578
main(){
	double v1, tanh_val;
	for (v1=-1; v1<=1; v1 +=.1){
		tanh_val = tanh(v1/RadianToDegree);
		printf("Hyperbolic tangent (%4.1f) = %7.3f\n", v1, tanh_val);
	}
}

/* time.c */
#include <stdlib.h>
#include <time.h>
main(){
	time_t current_time;
	current_time=time(NULL);
	printf("%d seconds since January 1, 1970\n", current_time);
}

/* tmpfile.c 暫存檔 */
#include <stdlib.h>
main(){
	FILE *tmp;

	if ((tmp = tmpfile()) == NULL) {
		printf("Cannot create temporary file.\n");
		exit(0);
	}
	else
		printf("Temporary file is successfully opened.\n");

	printf("Write a message :\n'You cannot see this message at any files.'"
		   "\nto temporary file...\n");
	fprintf(tmp, "You cannot see this message at any files.");

	printf("Close temoprary file...\n");
	fclose(tmp);
}

/* tmpnam.c 產生暫存檔名稱 */
#include <stdlib.h>
main(){
	char tmpname[3][L_tmpnam];

	tmpnam(tmpname[0]);
	tmpnam(tmpname[1]);
	tmpnam(tmpname[2]);

	printf("Temporary name 0: %s\n", tmpname[0]);
	printf("Temporary name 1: %s\n", tmpname[1]);
	printf("Temporary name 2: %s\n", tmpname[2]);
	printf("Temporary name in internal static object : %s\n", tmpnam(NULL));
}

/* tolower.c */
#include <ctype.h>
#include <stdlib.h>
main(){
	char s[20];
	int i;
	printf("Enter a string: ");
	gets(s);
	for (i=0; (s[i]!=' ') && (s[i]!='\0'); i++)
		s[i] = tolower(s[i]);
	printf("Converted string is: %s\n", s);
}

/* toupper.c */
#include <ctype.h>
#include <stdlib.h>
main(){
	char s[20];
	int i;
	printf("Enter a string: ");
	gets(s);
	for (i=0; (s[i]!=' ') && (s[i]!='\0'); i++)
		s[i] = toupper(s[i]);
	printf("Converted string is: %s\n", s);
}

/* ungetc.c */
#include <stdlib.h>
main(){
	int ch;
	printf("Please enter a character: ");
	ch = getchar();
	printf("put back the character to the buffer of stdin...\n");
	ungetc(ch, stdin);

	printf("The character got from the buffer is: %c\n", getchar());
}

/* va_arg.c 可改變參數數目 */
#include <stdarg.h>
#include <stdlib.h>

/* Function Prototyping */
int Add(int, ...);

main(){
	int total=0;
	total=Add(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, -999);
	printf( "1+2+3+,...+10= %d\n", total);
}

/* The function "Add" will add the all arguments up. */
int Add(int i, ...){
	int sum = 0;
	va_list argp;
	va_start(argp, i);	// Initialize the pointer - argp

	while (i != -999) {
		sum += i;
		i = va_arg(argp, int);
	}
	va_end(argp);
	return(sum);
}

/* vfprintf.c */
#include <stdarg.h>
#include <stdlib.h>

int myfprintf(FILE *fp, char *format, ...){
	va_list arglist;
	int     numbers;

	va_start(arglist, format);
	numbers = vfprintf(fp, format, arglist);
	va_end(arglist);
	return numbers;
}

main(){
	int   i    = 200;
	char  ch   = 'A';
	float f    = 3.1415f;
	char  *str = "This is a test.";

	printf("write '%d', '%c', '%f', and '%s' to stdout...\n", i, ch, f, str);
	myfprintf(stdout, "%d, %c, %f, %s", i, ch, f, str);
	printf("\n");
}

/* vprintf.c */
#include <stdarg.h>
#include <stdlib.h>

int myvprintf(char *format, ...){
	va_list arglist;
	int     numbers;

	va_start(arglist, format);
	numbers = vprintf(format, arglist);
	va_end(arglist);

	return numbers;
}

main(){
	int   i    = 200;
	char  ch   = 'A';
	float f    = 3.1415f;
	char  *str = "This is a test.";

	printf("write '%d', '%c', '%f', and '%s' to stdout...\n", i, ch, f, str);
	myvprintf("%d, %c, %f, %s", i, ch, f, str);
	printf("\n");
}

/* vsprintf.c */
#include <stdarg.h>
#include <stdlib.h>

int myvsprintf(char *format, ...){
	va_list arglist;
	int numbers;
	char s[100];

	va_start(arglist, format);
	numbers = vsprintf(s, format, arglist);
	va_end(arglist);

	puts(s);
	return numbers;
}

main(){
	myvsprintf("The number %d in hexadecimal is %#x.\n", 100, 100);
}