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<P><font color="#003399">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> </font>
<P><font color="#003399">int main(void) <BR>
{ <BR>
printf("Calling abort()\n"); <BR>
abort(); <BR>
return 0; /* This is never reached */ <BR>
} <BR>
<BR>
</font>
<P><font color="#003399">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> </font>
<P><font color="#003399">int main(void) <BR>
{ <BR>
int number = -1234; </font>
<P><font color="#003399"> printf("number: %d absolute value: %d\n",
number, abs(number)); <BR>
return 0; <BR>
} <BR>
<BR>
</font>
<P><font color="#003399">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 */ </font>
<P><font color="#003399">#include <stdio.h> <BR>
#include <conio.h> <BR>
#include <process.h> <BR>
#include <dos.h> </font>
<P><font color="#003399">int main(void) <BR>
{ <BR>
int i, strt, ch_out, sector; <BR>
char buf[512]; </font>
<P><font color="#003399"> 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>
</font>
<P><font color="#003399">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> </font>
<P><font color="#003399">int file_exists(char *filename); </font>
<P><font color="#003399">int main(void) <BR>
{ <BR>
printf("Does NOTEXIST.FIL exist: %s\n", <BR>
file_exists("NOTEXISTS.FIL") ? "YES" : "NO"); <BR>
return 0; <BR>
} </font>
<P><font color="#003399">int file_exists(char *filename) <BR>
{ <BR>
return (access(filename, 0) == 0); <BR>
} <BR>
</font>
<P><font color="#003399">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> </font>
<P><font color="#003399">int main(void) <BR>
{ <BR>
double result; <BR>
double x = 0.5; </font>
<P><font color="#003399"> result = acos(x); <BR>
printf("The arc cosine of %lf is %lf\n", x, result); <BR>
return 0; <BR>
} <BR>
<BR>
</font>
<P><font color="#003399">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> </font>
<P><font color="#003399">int main(void) <BR>
{ <BR>
unsigned int size, segp; <BR>
int stat; </font>
<P><font color="#003399"> 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); </font>
<P><font color="#003399"> return 0; <BR>
} <BR>
<BR>
</font>
<P><font color="#003399">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> </font>
<P><font color="#003399">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; </font>
<P><font color="#003399"> /* initialize graphics and local variables
*/ <BR>
initgraph(&gdriver, &gmode, ""); </font>
<P class="未命名1"><font color="#003399"> /* 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(); </font>
<P><font color="#003399"> exit(1);
/* terminate with an error code */ <BR>
} </font>
<P><font color="#003399"> midx = getmaxx() / 2; <BR>
midy = getmaxy() / 2; <BR>
setcolor(getmaxcolor()); </font>
<P><font color="#003399"> /* draw arc */ <BR>
arc(midx, midy, stangle, endangle, radius); </font>
<P><font color="#003399"> /* clean up */ <BR>
getch(); <BR>
closegraph(); <BR>
return 0; <BR>
} <BR>
<BR>
</font>
<P><font color="#003399">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> </font>
<P><font color="#003399">int main(void) <BR>
{ <BR>
struct tm t; <BR>
char str[80]; </font>
<P><font color="#003399"> /* sample loading of tm structure
*/ </font>
<P><font color="#003399"> 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 */ </font>
<P><font color="#003399"> /* converts structure to null terminated
<BR>
string */ </font>
<P><font color="#003399"> strcpy(str, asctime(&t)); <BR>
printf("%s\n", str); </font>
<P><font color="#003399"> return 0; <BR>
} <BR>
<BR>
<BR>
</font>
<P><font color="#003399">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> </font>
<P><font color="#003399">int main(void) <BR>
{ <BR>
double result; <BR>
double x = 0.5; </font>
<P><font color="#003399"> result = asin(x); <BR>
printf("The arc sin of %lf is %lf\n", x, result); <BR>
return(0); <BR>
} <BR>
<BR>
<BR>
</font>
<P><font color="#003399">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> </font>
<P><font color="#003399">struct ITEM { <BR>
int key; <BR>
int value; <BR>
}; </font>
<P><font color="#003399">/* 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>
} </font>
<P><font color="#003399">int main(void) <BR>
{ <BR>
additem(NULL); <BR>
return 0; <BR>
} <BR>
<BR>
<BR>
</font>
<P><font color="#003399">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> </font>
<P><font color="#003399">int main(void) <BR>
{ <BR>
double result; <BR>
double x = 0.5; </font>
<P><font color="#003399"> result = atan(x); <BR>
printf("The arc tangent of %lf is %lf\n", x, result); <BR>
return(0); <BR>
} <BR>
<BR>
</font>
<P><font color="#003399">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> </font>
<P><font color="#003399">int main(void) <BR>
{ <BR>
double result; <BR>
double x = 90.0, y = 45.0; </font>
<P><font color="#003399"> result = atan2(y, x); <BR>
printf("The arc tangent ratio of %lf is %lf\n", (y / x), result);
<BR>
return 0; <BR>
} <BR>
<BR>
</font>
<P><font color="#003399">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> </font>
<P><font color="#003399">void exit_fn1(void) <BR>
{ <BR>
printf("Exit function #1 called\n"); <BR>
} </font>
<P><font color="#003399">void exit_fn2(void) <BR>
{ <BR>
printf("Exit function #2 called\n"); <BR>
} </font>
<P><font color="#003399">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>
</font>
<P><font color="#003399">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> </font>
<P><font color="#003399">int main(void) <BR>
{ <BR>
float f; <BR>
char *str = "12345.67"; </font>
<P><font color="#003399"> f = atof(str); <BR>
printf("string = %s float = %f\n", str, f); <BR>
return 0; <BR>
} <BR>
<BR>
</font>
<P><font color="#003399">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> </font>
<P><font color="#003399">int main(void) <BR>
{ <BR>
int n; <BR>
char *str = "12345.67"; </font>
<P><font color="#003399"> n = atoi(str); <BR>
printf("string = %s integer = %d\n", str, n); <BR>
return 0; <BR>
} <BR>
<BR>
</font>
<P><font color="#003399">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: </font>
<P><font color="#003399">#include <stdlib.h> <BR>
#include <stdio.h> </font>
<P><font color="#003399">int main(void) <BR>
{ <BR>
long l; <BR>
char *str = "98765432"; </font>
<P class="未命名1"><font color="#003399"> l = atol(lstr); <BR>
printf("string = %s integer = %ld\n", str, l); <BR>
return(0); <BR>
} <BR>
</font>
<P><font color="#003399">
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<P><font color="#003399"> </font>
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