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Turbo C 2.0、Borland C++库函数及用例(22) int handle; char msg[] = "This is a test";
char ch;
/* create a file */
handle = open("DUMMY.FIL",
O_CREAT O_RDWR,
S_IREAD S_IWRITE);
/* write some data to the file */
write(handle, msg, strlen(msg)); /* seek to the beginning of the file */
lseek(handle, 0L, SEEK_SET); /* reads chars from the file until hit EOF */
do
{ read(handle, &ch, 1);
printf("%c", ch);
} while (!eof(handle)); close(handle);
return 0;
}
函数名: exec...
功 能: 装入并运行其它程序的函数
用 法: int execl( char *pathname, char *arg0, arg1, ...,
argn, NULL );
int execle( char *pathname, char *arg0, arg1, ...,
argn, NULL, char *envp[] );
int execlp( char *pathname, char *arg0, arg1, ..,
NULL );
int execple( char *pathname, char *arg0, arg1, ...,
NULL, char *envp[] );
int execv( char *pathname, char *argv[] );
int execve( char *pathname, char *argv[],
char *envp[] );
int execvp( char *pathname, char *argv[] ); int execvpe( char *pathname, char *argv[],
char *envp[] );
程序例:/* execv example */
#include <process.h>
#include <stdio.h>
#include <errno.h>
void main(int argc, char *argv[])
{
int i; printf("Command line arguments:\n"); for (i=0; i<argc; i++)
printf("[%2d] : %s\n", i, argv[i]);
printf("About to exec child with arg1 arg2 ...\n");
execv("CHILD.EXE", argv);
perror("exec error");
exit(1);
}
函数名: exit
功 能: 终止程序
用 法: void exit(int status);
程序例:#include <stdlib.h>
#include <conio.h>
#include <stdio.h>int main(void)
{
int status; printf("Enter either 1 or 2\n"); status = getch();
/* Sets DOS errorlevel */
exit(status - '0');/* Note: this line is never reached */
return 0;
}
函数名: eXP
功 能: 指数函数
用 法: double exp(double x);
程序例:#include <stdio.h>
#include <math.h>int main(void)
{
double result;
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