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<P>函数名: abort
<BR>功 能: 异常终止一个进程
<BR>用 法: void abort(void);
<BR>程序例:
<BR>#include <stdio.h>
<BR>#include <stdlib.h>
<P>int main(void)
<BR>{
<BR> printf("Calling abort()\n");
<BR> abort();
<BR> return 0; /* This is never reached */
<BR>}
<BR>
<BR>
<P>函数名: abs
<BR>功 能: 求整数的绝对值
<BR>用 法: int abs(int i);
<BR>程序例:
<BR>#include <stdio.h>
<BR>#include <math.h>
<P>int main(void)
<BR>{
<BR> int number = -1234;
<P> printf("number: %d absolute value: %d\n", number, abs(number));
<BR> return 0;
<BR>}
<BR>
<BR>
<P>函数名: absread, abswirte
<BR>功 能: 绝对磁盘扇区读、写数据
<BR>用 法: int absread(int drive, int nsects, int sectno, void *buffer);
<BR> int abswrite(int drive, int nsects, in tsectno, void *buffer);
<BR>程序例:
<BR>/* absread example */
<P>#include <stdio.h>
<BR>#include <conio.h>
<BR>#include <process.h>
<BR>#include <dos.h>
<P>int main(void)
<BR>{
<BR> int i, strt, ch_out, sector;
<BR> char buf[512];
<P> printf("Insert a diskette into drive A and press any key\n");
<BR> getch();
<BR> sector = 0;
<BR> if (absread(0, 1, sector, &buf) != 0)
<BR> {
<BR> perror("Disk problem");
<BR> exit(1);
<BR> }
<BR> printf("Read OK\n");
<BR> strt = 3;
<BR> for (i=0; i<80; i++)
<BR> {
<BR> ch_out = buf[strt+i];
<BR> putchar(ch_out);
<BR> }
<BR> printf("\n");
<BR> return(0);
<BR>}
<BR>
<BR>
<BR>
<P>函数名: access
<BR>功 能: 确定文件的访问权限
<BR>用 法: int access(const char *filename, int amode);
<BR>程序例:
<BR>#include <stdio.h>
<BR>#include <io.h>
<P>int file_exists(char *filename);
<P>int main(void)
<BR>{
<BR> printf("Does NOTEXIST.FIL exist: %s\n",
<BR> file_exists("NOTEXISTS.FIL") ? "YES" : "NO");
<BR> return 0;
<BR>}
<P>int file_exists(char *filename)
<BR>{
<BR> return (access(filename, 0) == 0);
<BR>}
<BR>
<P>函数名: acos
<BR>功 能: 反余弦函数
<BR>用 法: double acos(double x);
<BR>程序例:
<BR>#include <stdio.h>
<BR>#include <math.h>
<P>int main(void)
<BR>{
<BR> double result;
<BR> double x = 0.5;
<P> result = acos(x);
<BR> printf("The arc cosine of %lf is %lf\n", x, result);
<BR> return 0;
<BR>}
<BR>
<BR>
<P>函数名: allocmem
<BR>功 能: 分配DOS存储段
<BR>用 法: int allocmem(unsigned size, unsigned *seg);
<BR>程序例:
<BR>#include <dos.h>
<BR>#include <alloc.h>
<BR>#include <stdio.h>
<P>int main(void)
<BR>{
<BR> unsigned int size, segp;
<BR> int stat;
<P> size = 64; /* (64 x 16) = 1024 bytes */
<BR> stat = allocmem(size, &segp);
<BR> if (stat == -1)
<BR> printf("Allocated memory at segment: %x\n",
segp);
<BR> else
<BR> printf("Failed: maximum number of paragraphs
available is %u\n",
<BR>
stat);
<P> return 0;
<BR>}
<BR>
<BR>
<P>函数名: arc
<BR>功 能: 画一弧线
<BR>用 法: void far arc(int x, int y, int stangle, int endangle,
int radius);
<BR>程序例:
<BR>#include <graphics.h>
<BR>#include <stdlib.h>
<BR>#include <stdio.h>
<BR>#include <conio.h>
<P>int main(void)
<BR>{
<BR> /* request auto detection */
<BR> int gdriver = DETECT, gmode, errorcode;
<BR> int midx, midy;
<BR> int stangle = 45, endangle = 135;
<BR> int radius = 100;
<P> /* initialize graphics and local variables */
<BR> initgraph(&gdriver, &gmode, "");
<P> /* read result of initialization */
<BR> errorcode = graphresult(); /* an error
occurred */
<BR> if (errorcode != grOk)
<BR> {
<BR> printf("Graphics error: %s\n", grapherrormsg(errorcode));
<BR> printf("Press any key to halt:");
<BR> getch();
<P> exit(1); /* terminate
with an error code */
<BR> }
<P> midx = getmaxx() / 2;
<BR> midy = getmaxy() / 2;
<BR> setcolor(getmaxcolor());
<P> /* draw arc */
<BR> arc(midx, midy, stangle, endangle, radius);
<P> /* clean up */
<BR> getch();
<BR> closegraph();
<BR> return 0;
<BR>}
<BR>
<BR>
<P>函数名: asctime
<BR>功 能: 转换日期和时间为ASCII码
<BR>用 法: char *asctime(const struct tm *tblock);
<BR>程序例:
<BR>#include <stdio.h>
<BR>#include <string.h>
<BR>#include <time.h>
<P>int main(void)
<BR>{
<BR> struct tm t;
<BR> char str[80];
<P> /* sample loading of tm structure */
<P> t.tm_sec = 1; /* Seconds */
<BR> t.tm_min = 30; /* Minutes */
<BR> t.tm_hour = 9; /* Hour */
<BR> t.tm_mday = 22; /* Day of the Month
*/
<BR> t.tm_mon = 11; /* Month */
<BR> t.tm_year = 56; /* Year - does not include
century */
<BR> t.tm_wday = 4; /* Day of the week
*/
<BR> t.tm_yday = 0; /* Does not show in asctime
*/
<BR> t.tm_isdst = 0; /* Is Daylight SavTime; does
not show in asctime */
<P> /* converts structure to null terminated
<BR> string */
<P> strcpy(str, asctime(&t));
<BR> printf("%s\n", str);
<P> return 0;
<BR>}
<BR>
<BR>
<BR>
<P>函数名: asin
<BR>功 能: 反正弦函数
<BR>用 法: double asin(double x);
<BR>程序例:
<BR>#include <stdio.h>
<BR>#include <math.h>
<P>int main(void)
<BR>{
<BR> double result;
<BR> double x = 0.5;
<P> result = asin(x);
<BR> printf("The arc sin of %lf is %lf\n", x, result);
<BR> return(0);
<BR>}
<BR>
<BR>
<BR>
<P>函数名: assert
<BR>功 能: 测试一个条件并可能使程序终止
<BR>用 法: void assert(int test);
<BR>程序例:
<BR>#include <assert.h>
<BR>#include <stdio.h>
<BR>#include <stdlib.h>
<P>struct ITEM {
<BR> int key;
<BR> int value;
<BR>};
<P>/* add item to list, make sure list is not null */
<BR>void additem(struct ITEM *itemptr) {
<BR> assert(itemptr != NULL);
<BR> /* add item to list */
<BR>}
<P>int main(void)
<BR>{
<BR> additem(NULL);
<BR> return 0;
<BR>}
<BR>
<BR>
<BR>
<P>函数名: atan
<BR>功 能: 反正切函数
<BR>用 法: double atan(double x);
<BR>程序例:
<BR>#include <stdio.h>
<BR>#include <math.h>
<P>int main(void)
<BR>{
<BR> double result;
<BR> double x = 0.5;
<P> result = atan(x);
<BR> printf("The arc tangent of %lf is %lf\n", x, result);
<BR> return(0);
<BR>}
<BR>
<BR>
<P>函数名: atan2
<BR>功 能: 计算Y/X的反正切值
<BR>用 法: double atan2(double y, double x);
<BR>程序例:
<BR>#include <stdio.h>
<BR>#include <math.h>
<P>int main(void)
<BR>{
<BR> double result;
<BR> double x = 90.0, y = 45.0;
<P> result = atan2(y, x);
<BR> printf("The arc tangent ratio of %lf is %lf\n", (y / x),
result);
<BR> return 0;
<BR>}
<BR>
<BR>
<P>函数名: atexit
<BR>功 能: 注册终止函数
<BR>用 法: int atexit(atexit_t func);
<BR>程序例:
<BR>#include <stdio.h>
<BR>#include <stdlib.h>
<P>void exit_fn1(void)
<BR>{
<BR> printf("Exit function #1 called\n");
<BR>}
<P>void exit_fn2(void)
<BR>{
<BR> printf("Exit function #2 called\n");
<BR>}
<P>int main(void)
<BR>{
<BR> /* post exit function #1 */
<BR> atexit(exit_fn1);
<BR> /* post exit function #2 */
<BR> atexit(exit_fn2);
<BR> return 0;
<BR>}
<BR>
<BR>
<BR>
<P>函数名: atof
<BR>功 能: 把字符串转换成浮点数
<BR>用 法: double atof(const char *nptr);
<BR>程序例:
<BR>#include <stdlib.h>
<BR>#include <stdio.h>
<P>int main(void)
<BR>{
<BR> float f;
<BR> char *str = "12345.67";
<P> f = atof(str);
<BR> printf("string = %s float = %f\n", str, f);
<BR> return 0;
<BR>}
<BR>
<BR>
<P>函数名: atoi
<BR>功 能: 把字符串转换成长整型数
<BR>用 法: int atoi(const char *nptr);
<BR>程序例:
<BR>#include <stdlib.h>
<BR>#include <stdio.h>
<P>int main(void)
<BR>{
<BR> int n;
<BR> char *str = "12345.67";
<P> n = atoi(str);
<BR> printf("string = %s integer = %d\n", str, n);
<BR> return 0;
<BR>}
<BR>
<BR>
<P>函数名: atol
<BR>功 能: 把字符串转换成长整型数
<BR>用 法: long atol(const char *nptr);
<BR>程序例:
<P>#include <stdlib.h>
<BR>#include <stdio.h>
<P>int main(void)
<BR>{
<BR> long l;
<BR> char *str = "98765432";
<P> l = atol(lstr);
<BR> printf("string = %s integer = %ld\n", str, l);
<BR> return(0);
<BR>}
<BR>
<P>
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