C语言函数大全--a开头的函数

#include <stdio.h>
#include <stdlib.h>

int main(void)
{
    printf("Calling abort()\n");
    abort();
    printf("already abort()"); // 这里永远也到不了
    return 0; 
}

#include <stdio.h>
#include <math.h>

int main(void)
{
    int number = -666;
  	printf("number: %d  absolute value: %d\n", number, 	abs(number));
  	return 0;
}

#include <stdio.h>
#include <conio.h>
#include <process.h>
#include <dos.h>

int main(void)
{
  	int i, strt, ch_out, sector;
  	char buf[512];

  	printf("Insert a diskette into drive A and press any key\n");
  	getch();
  	sector = 0;
  	if (absread(0, 1, sector, &buf) != 0)
  	{
     	perror("Disk problem");
     	exit(1);
  	}
  	printf("Read OK\n");
  	strt = 3;
  	for (i=0; i<80; i++)
  	{
     	ch_out = buf[strt+i];
     	putchar(ch_out);
  	}
  	printf("\n");
  	return(0);
}

#include <dos.h>
#include <stdio.h>

unsigned char buff[512];

int main()
{
    int i;
    char c;
    printf("\nQuick Format 1.44MB\n");
    printf("Program by ChenQingyang.\n");
    printf("ALL DATA IN THE FLOPPY DISK WILL BE LOST!!\n");
    printf("\nInsert a diskette for drive A:\n");
    printf("and press ENTER when ready. . .");
    c=getchar();
    printf("\n\nCleaning FAT area. . .");
    buff[0]=0xf0;
    buff[1]=buff[2]=0xff;
    for (i=3;i<512;i++) 
        buff[i]=0;
    abswrite(0,1,1,buff);
    abswrite(0,1,10,buff);
    for (i=0;i<512;i++) 
        buff[i]=0;
    for (i=2;i<10;i++) 
        abswrite (0,1,i,buff);
    for (i=11;i<19;i++) 
        abswrite (0,1,i,buff);
    printf("\nCleaning ROOT area. . .");
    for (i=19;i<33;i++) 
        abswrite (0,1,i,buff);
    printf("\n\nQuickFormat Completed!\n");
}

#include <stdio.h>
#include <io.h>

int file_exists(char *filename);

int main(void)
{
    printf("Does students1.txt exist: %s\n",
    file_exists("students1.txt") ? "YES" : "NO");
    return 0;
}

int file_exists(char *filename)
{
    return (access(filename, 0) == 0);
}

#include <stdio.h>
#include <math.h>

int main(void)
{
    double result;
    double x = 0.5;

    result = acos(x); 
    printf("The arc cosine of %lf is %lf\n", x, result);
    return 0;
}

#include <dos.h>
#include <alloc.h>
#include <stdio.h>

int main(void)
{
    unsigned int size, segp;
    int stat;
    size = 64; /* (64 x 16) = 1024 bytes */
    stat = allocmem(size, &segp);
    if (stat == -1)
        printf("Allocated memory at segment: %x\n", segp);
    else
        printf("Failed: maximum number of paragraphs available is %u\n",stat);
    return 0;
}

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>

int main(void)
{
    /* request auto detection */
    int gdriver = DETECT, gmode, errorcode;

    int midx, midy;
    int stangle = 45, endangle = 135;
    int radius = 100;

    /* initialize graphics and local variables */
    char ch[] = "";
    initgraph(&gdriver, &gmode, ch);

    /* read result of initialization */
    errorcode = graphresult();    /* an error occurred */
    if (errorcode != grOk)
    {
        printf("Graphics error: %s\n", grapherrormsg(errorcode));
        printf("Press any key to halt:");
        getch();
        exit(1);    /* terminate with an error code */
    }

    midx = getmaxx() / 2;
    midy = getmaxy() / 2;
    setcolor(getmaxcolor());

    /* draw arc */
    arc(midx, midy, stangle, endangle, radius);

    /* clean up */
    getch();
    closegraph();
    return 0;
}

#include <stdio.h>
#include <string.h>
#include <time.h>

int main(void)
{
    struct tm t;
    char str[80];

    /* sample loading of tm structure  */

    t.tm_sec    = 1;  /* Seconds */
    t.tm_min    = 30; /* Minutes */
    t.tm_hour   = 9;  /* Hour */
    t.tm_mday   = 22; /* Day of the Month  */
    t.tm_mon    = 11; /* Month */
    t.tm_year   = 56; /* Year - does not include century */
    t.tm_wday   = 4;  /* Day of the week  */
    t.tm_yday   = 0;  /* Does not show in asctime  */
    t.tm_isdst  = 0;  /* Is Daylight SavTime; does not show in asctime */

    /* converts structure to null terminated
    string */

    strcpy(str, asctime(&t));
    printf("%s\n", str);

    return 0;
}

#include <stdio.h>
#include <math.h>

int main(void)
{
    double result;
    double x = 0.5;

    result = asin(x);
    printf("The arc sin of %lf is %lf\n", x, result);
    return(0);
}

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>

struct ITEM {
   int key;
   int value;
};

/* add item to list, make sure list is not null */
void additem(struct ITEM *itemptr) {
    assert(itemptr != NULL);
   /* add item to list */
}

int main(void)
{
    additem(NULL);
    return 0;
}

#include <stdio.h>
#include <math.h>

int main(void)
{
    double result;
    double x = 0.5;

    result = atan(x);
    printf("The arc tangent of %lf is %lf\n", x, result);
    return(0);
}

#include <stdio.h>
#include <math.h>

int main(void)
{
	double result;
	double x = 60.0, y = 30.0;

	result = atan2(y, x);
	printf("The arc tangent ratio of %lf is %lf\n", (y / x), result);
	return 0;
}

#include <stdio.h>
#include <stdlib.h>

void exit_fn1(void)
{
    printf("Exit function #1 called\n");
}

void exit_fn2(void)
{
    printf("Exit function #2 called\n");
}

int main(void)
{
    /* post exit function #1 */
    atexit(exit_fn1);
    /* post exit function #2 */
    atexit(exit_fn2);
    return 0;
}

#include <stdlib.h>
#include <stdio.h>

int main(void)
{
    float f;
    char *str = "1234.5678";

    f = atof(str);
    printf("string = %s float = %f\n", str, f);
    return 0;
}

#include <stdlib.h>
#include <stdio.h>

int main(void)
{
    int n;
    char *str = "1234.5678";

    n = atoi(str);
    printf("string = %s integer = %d\n", str, n);
    return 0;
}

#include <stdlib.h>
#include <stdio.h>

int main(void)
{
    long l;
    char *lstr = "87654321";

    l = atol(lstr);
    printf("string = %s integer = %ld\n", lstr, l);
    return(0);
}