UNIX环境高级编程学习之第三章文件IO-文件读操作

UNIX环境高级编程学习之第三章文件IO-文件读操作

#include <stdio.h>#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <unistd.h>#include <stdlib.h>#include <string.h>#include <errno.h>int err_sys(const char * str){printf("%s/n", str);exit(-1);return 0;}int main(int argc, char *argv[]){int fd;fd = open("./a.txt", O_RDONLY);if (-1 == fd){err_sys(strerror(errno));}int i;double d;float f;char c;char str[100] = { '/0' };int ret = read(fd, &i, sizeof(i));if (ret != 4){err_sys("read error!");}ret = read(fd, &d, sizeof(double));if (ret != sizeof(double)){err_sys("read error! ");}ret = read(fd, &f, sizeof(f));if (ret != sizeof(f)){err_sys("read error!");}ret = read(fd, &c, sizeof(c));if (ret != sizeof(c)){err_sys("read error!");}ret = read(fd, str, sizeof(str));if (ret != sizeof(str)){err_sys("read error!");} close(fd); printf("i=%d, d=%lf, f=%f, c=%c, str=%s/n", i, d, f, c, str);}