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函数大全(a开头)

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发表于 2004-10-4 03:03 |只看该作者 |倒序浏览

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<

align=center>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 <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 <

ROCESS.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("

ress 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);
}

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