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); }