打开文件和写文件的操作

使用系统调用的：open好write

代码：

//打开文件和写问件#include <stdio.h>#include <stdlib.h>#include <string.h>#include <unistd.h>#include <sys/stat.h>#include <sys/fcntl.h>#include <sys/types.h>#include <errno.h>const char* msg = "hello world \n";int main(){ close(1); //close(2); int fd = open("./log",O_CREAT|O_RDWR,0666);  //int fd1 = open("./log1",O_CREAT|O_RDWR,0666); //int fd2 = open("./log2",O_CREAT|O_RDWR,0666); //int fd3 = open("./log3",O_CREAT|O_RDWR,0666); if(fd < 0 ) {    exit(-1); } printf("%d\n",fd); int i = 10; //printf("%d\n",fd1); //printf("%d\n",fd2); //printf("%d\n",fd3); while(i) {   i--;   write(fd,msg,strlen(msg)); } close(fd); //close(fd1); //close(fd2); //close(fd3); return 0;}

运行结果：

分析：使用>log可以创建一个log文件，不使用的话这个程序是不会自动创建log文件的