功能名称: abort

动力 能够: 异常终止的过程的

使用 法国: void abort(void);

程序示例:

#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: 确定文件的訪问权限

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: 測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: 注冊终止函数

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);
} 

由 书法新软件 整理 阅读更满意、更舒适的书写、出版更容易