Linux下的IO/文件操作练习,知识虽然简单 但是往往基础容易被忽略,偶尔的练习是有必要的。
练习printf
/*************************************************************************> File Name: printf.c> Author: > Mail: > Created Time: Wed 11 Feb 01:08:15 AM PST************************************************************************/#include<stdio.h>int main(){ printf("%10s\n","hello");printf("%-10s\n","hello");printf("%s\n","hello") ;printf("%*s\n",10,"hello") ;printf("%010d\n",100) ;printf("%10.4g\n",1.22) ;printf("%10s\n","Hello,I am a programmer !") ;return 0 ;}
练习C标准库的文件复制 相比系统调用 会快 因为有缓冲
/*************************************************************************> File Name: cpy.c> Author: > Mail: > Created Time: Wed 11 Feb 01:37:56 AM PST************************************************************************/#include<stdio.h>int main(){ int c;FILE*in=fopen("./printf","r");FILE*out=fopen("./printf_tem","w");while((c=fgetc(in))!=EOF){fputc(c,out) ;}exit(0);}
练习查看一个文件的状态
/*************************************************************************> File Name: fileinfo.c> Author: > Mail: > Created Time: Wed 11 Feb 11:25:21 PM PST************************************************************************/#include<stdio.h>#include<sys/stat.h>#include<unistd.h> int main(){ int fileNo;struct stat fileStat ;FILE*pFile= fopen("./cpy","r");if(pFile==NULL){printf("File Open Error!\n") ;exit(0);}fileNo= fileno(pFile);printf("FileNumber:%d\n",fileNo) ;if(-1==fstat(fileNo,&fileStat)){printf("GetFileInfo Error!\n") ;exit(0) ;}printf("DeviceID:%d\n",fileStat.st_dev);printf("UserID:%d\n",fileStat.st_uid);printf("GroupID:%d\n",fileStat.st_gid);printf("FileSize:%d\n",fileStat.st_size);return 0 ;}
我们模拟Linux下的ls程序
/*************************************************************************> File Name: listdir.c> Author: > Mail: > Created Time: Thu 12 Feb 12:49:13 AM PST************************************************************************/#include<stdio.h>#include<unistd.h>#include<sys/stat.h>#include<dirent.h>#include<string.h>#include<sys/types.h>void list_func(char*path,int depth) { DIR*pDirHandle= opendir(path);struct dirent * dent ;struct stat fstat ;if(pDirHandle==NULL){printf("OpenDir %s Error!\n",path);exit(0);}chdir(path);while((dent=readdir(pDirHandle))!=NULL){ //error then return -1 lstat(dent->d_name,&fstat);if(S_ISDIR(fstat.st_mode)){ //remove director . and ..if(strcmp(".",dent->d_name)==0||strcmp("..",dent->d_name)==0 )continue ;printf("%*s%s/\n",depth,"",dent->d_name) ;list_func(dent->d_name,depth+4) ;}elseprintf("%*s%s\n",depth,"",dent->d_name); }chdir("..");closedir(pDirHandle);}int main(int argc,char**argv){ if(argc<2){printf("Param Format: listdir path\n");return ;}char*pDirPath=argv[1];int depath=0;printf("List Begin:\n");list_func(pDirPath,depath) ;printf("List End.\n");return 0 ;}
格式化错误代码
/*************************************************************************> File Name: errformat.c> Author: > Mail: > Created Time: Fri 13 Feb 12:50:00 AM PST************************************************************************/#include<stdio.h>#include<errno.h>#include<stdlib.h>#include<string.h>int main(){ char* message=NULL ;//errorfopen("aaaaa","r") ;// printf(strerror(errno));message=strerror(errno);if(message!=NULL)printf("Error:%s\n",message);perror("Program:");return 0;}
