Ｃ语言函数大全(A开头)

    函数名: abort
    功 能: 异常终止一个进程
    用 法: void abort(void);
    程序例:
    #include
    #include
    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
    #include
    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
    #include
    #include
    #include
    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
    #include
    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
    #include
    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
    #include
    #include
    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
    #include
    #include
    #include
    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)); [Page]
    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
    #include
    #include
    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
    #include
    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
    #include
    #include
    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
    #include
    int main(void)
    {
    double result;
    double x = 0.5;