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Turbo C 2.0、Borland C++库函数及用例(20) DOS buffer */
close(duphandle);
}
函数名: dup2
功 能: 复制文件句柄
用 法: int dup2(int oldhandle, int newhandle);
程序例:#include <sys\stat.h>
#include <string.h>
#include <fcntl.h>
#include <io.h>int main(void)
{
#define STDOUT 1
int nul, oldstdout;
char msg[] = "This is a test"; /* create a file */
nul = open("DUMMY.FIL", O_CREAT O_RDWR,
S_IREAD S_IWRITE); /* create a duplicate handle for standard
output */
oldstdout = dup(STDOUT);
/*
redirect standard output to DUMMY.FIL
by duplicating the file handle onto the
file handle for standard output. */ dup2(nul, STDOUT);
/* close the handle for DUMMY.FIL */
close(nul); /* will be redirected into DUMMY.FIL */
write(STDOUT, msg, strlen(msg)); /* restore original standard output
handle */
dup2(oldstdout, STDOUT); /* close duplicate handle for STDOUT */
close(oldstdout);
return 0;
}字母Ｅ开头函数
函数名: ecvt
功 能: 把一个浮点数转换为字符串
用 法: char ecvt( double value, int ndigit, int *decpt,
int *sign );
程序例:#include <stdlib.h>
#include <stdio.h>
#include <conio.h>int main(void)
{
char *string;
double value; int dec, sign;
int ndig = 10; clrscr();
value = 9.876;
string = ecvt(value, ndig, &dec, &sign);
printf("string = %s dec = %d \
sign = %d\n", string, dec, sign);
value = -123.45;
ndig= 15;
string = ecvt(value,ndig,&dec,&sign);
printf("string = %s dec = %d sign = %d\n",
string, dec, sign); value = 0.6789e5; /* scientific
notation */
ndig = 5;
string = ecvt(value,ndig,&dec,&sign);
printf("string = %s dec = %d\
sign = %d\n", string, dec, sign); return 0;
}
函数名: ellipse
功 能: 画一椭圆
用 法: void far ellipse( int x, int y, int stangle,
int endangle, int xradius,
int yradius);
程序例:#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>int main(void)
{ /* request auto detection */
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