linux头文件引用问题
读文件尾的两个字节, 代码如下：#include <stdio.h>#include <errno.h>#include <sys/types.h>#include <sys/stat.h>#include <string.h>//#include <unistd.h>#include <fcntl.h>#define MSG_ERR printf#define S_OK 0#define S_FAILED 1int main(int argc, char *argv[]){ char *filename = "test.txt"; int ret; int r = S_FAILED; int fd = -1; int size = 0; struct stat statBuf; do { if(stat(filename, &statBuf) != 0) { printf("STAT file error.(%s)\n", strerror(errno)); break; } printf("file: %s length = %d", filename, statBuf.st_size); if((fd = open(filename, O_RDONLY)) == -1) { MSG_ERR("cannot open file: %s\n", filename); break; } else{ MSG_ERR("open file %s ok\n", filename); } ret = lseek(fd, -2, SEEK_END); //ret = lseek(fd, statBuf.st_size - 2, SEEK_CUR); if(ret == -1) { MSG_ERR("seek file '%s' error:%s\n", strerror(errno), filename); break; } else{ MSG_ERR("seek ok, ret = %d\n", ret); } //read the last 2 bytes ret = read(fd, &size, 2); if(ret != 2) { MSG_ERR("read file '%s' error:%s\n", strerror(errno), filename); MSG_ERR("ret=%d", ret); break; } else{ MSG_ERR("read ok, size = %d\n", size); } r = S_OK; // УÑéͨ¹ý }while(0); if(fd != -1){ close(fd); } return r;} 头文件string.h和unistd.h, 在RHEL5.4_x86_64上测试结果：
1.只使用string.h结果错误
2.只使用unistd.h正确
3.都用正确
4.都不用段错误
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