后一页前一页回目录回首页 A 函数名: abort 功  能: 异常终止一个进程 用  法: void abort(void); 程序例: #include <stdio.h> #include <stdlib.h> int main(void) {   printf("Calling abort()\n");   abort();   return 0; /* This is never reached */ }     函数名: abs 功  能: 求整数的绝对值 用  法: int abs(int i); 程序例: #include <stdio.h> #include <math.h> int main(void) {   int number = -1234;   printf("number: %d  absolute value: %d\n", number, abs(number));   return 0; }     函数名: absread, abswirte 功  能: 绝对磁盘扇区读、写数据 用  法: int absread(int drive, int nsects, int sectno, void *buffer);  int abswrite(int drive, int nsects, in tsectno, void *buffer); 程序例: /* absread example */ #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); }       函数名: access 功  能: 确定文件的访问权限 用  法: int access(const char *filename, int amode); 程序例: #include <stdio.h> #include <io.h> int file_exists(char *filename); int main(void) {   printf("Does NOTEXIST.FIL exist: %s\n",   file_exists("NOTEXISTS.FIL") ? "YES" : "NO");   return 0; } int file_exists(char *filename) {   return (access(filename, 0) == 0); }   函数名: acos 功  能: 反余弦函数 用  法: double acos(double x); 程序例: #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; }     函数名: allocmem 功  能: 分配DOS存储段 用  法: int allocmem(unsigned size, unsigned *seg); 程序例: #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; }     函数名: arc 功  能: 画一弧线 用  法: void far arc(int x, int y, int stangle, int endangle, int radius); 程序例: #include <graphics.h> #include <stdlib.h> #include <stdio.h> #include <conio.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 */    initgraph(&gdriver, &gmode, "");    /* 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; }     函数名: asctime 功  能: 转换日期和时间为ASCII码 用  法: char *asctime(const struct tm *tblock); 程序例: #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; }       函数名: asin 功  能: 反正弦函数 用  法: double asin(double x); 程序例: #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); }       函数名: assert 功  能: 测试一个条件并可能使程序终止 用  法: void assert(int test); 程序例: #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; }       函数名: atan 功  能: 反正切函数 用  法: double atan(double x); 程序例: #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); }     函数名: atan2 功  能: 计算Y/X的反正切值 用  法: double atan2(double y, double x); 程序例: #include <stdio.h> #include <math.h> int main(void) {    double result;    double x = 90.0, y = 45.0;    result = atan2(y, x);    printf("The arc tangent ratio of %lf is %lf\n", (y / x), result);    return 0; }     函数名: atexit 功  能: 注册终止函数 用  法: int atexit(atexit_t func); 程序例: #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; }       函数名: atof 功  能: 把字符串转换成浮点数 用  法: double atof(const char *nptr); 程序例: #include <stdlib.h> #include <stdio.h> int main(void) {    float f;    char *str = "12345.67";    f = atof(str);    printf("string = %s float = %f\n", str, f);    return 0; }     函数名: atoi 功  能: 把字符串转换成长整型数 用  法: int atoi(const char *nptr); 程序例: #include <stdlib.h> #include <stdio.h> int main(void) {    int n;    char *str = "12345.67";    n = atoi(str);    printf("string = %s integer = %d\n", str, n);    return 0; }     函数名: atol 功  能: 把字符串转换成长整型数 用  法: long atol(const char *nptr); 程序例: #include <stdlib.h> #include <stdio.h> int main(void) {    long l;    char *str = "98765432";    l = atol(lstr);    printf("string = %s integer = %ld\n", str, l);    return(0); }   后一页

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