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Turbo C 2.0、Borland C++库函数及用例(2) 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("Graph err: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* terminate with an error code */
} midx = getmaxx() / 2;
midy = getmaxy() / 2;
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