C学习笔记——打开文件，并保存错误信息

        这两天学习文件访问，产生了一个做个小程序的想法：打开一个文件，并把它的内容显示在屏幕上，如果不能打开，则记录当前时间和错误信息到错误文件中。

        运行时，把文件放入在cmd默认的目录（我这是C:\Users\Ralap）下，通过命令窗口（cmd）来控制。这把文件名命名为“OpenFile.exe”，在输入命令的时候，

        输入格式为：程序文件名     【需打开的文件名1】    【需打开的文件名2】……

        运行效果如下：

        总体思路为：

        1、通过命令后面的参数，打开文件。能打开便显示，无法打开便把错误信息输入到err.txt中

        2、处理里命令后面的参数后，再次询问是否需要打开其他文件。打开成功与否的处理与上面一样

        代码如下：

#include <stdio.h>#include <conio.h>#include <string.h>#include <stdlib.h>#include <time.h>#include <ctype.h>#include <direct.h>//get the current working directroy: getcwd()#define FILE_NAME_SIZE 50#define ERR_INFO_SIZE 100#define READ "r"#define WRITE "w"#define ADD "a"#define ERR_HANDLE_FILE "err.txt"char printFile(FILE *ifp, FILE *ofp){char c;while((c=getc(ifp)) != EOF)putc(c,ofp);return ferror(ofp) ? EOF : 1;}void errorHandle(char *errfname,char *s){time_t dtime;FILE *errp;if((errp=fopen(errfname,ADD)) == NULL){fprintf(stderr,"Error_handle file \"%s\" can't operated!",errfname);exit(1);//exit the program directly}else{dtime=time(NULL);//get the time of the nowfprintf(errp,"%s%s\n\n",ctime(&dtime),s);fclose(errp);}}/*stradd: stack the strings*/char stradd(char *destination, unsigned size, char *first, char *second, char *third){ /*若不判断长度，总长度过长会导致fname指针无效，在释放内存时将出现异常，中断在此函数CheckBytes()*/if(size <= strlen(first)+strlen(second)+strlen(third))return EOF;strcpy(destination,first);strcat(destination,second);strcat(destination,third);return 0;}int main(int argc, char **argv){char fpath[80];//the path of this fileFILE *fp;char *exe;char slct;char *fname;char errinfo[ERR_INFO_SIZE];exe=strrchr(*argv, '\\') == NULL ? *argv : (strrchr(*argv, '\\')+1);puts("********************************************************************");puts("***The function of this file is open a file which you want,      ***");puts("***and the error information will output to a error_handle file, ***");puts("***like err.txt                                                  ***");puts("********************************************************************");if(getcwd(fpath,sizeof(fpath)) == NULL)//print current working directoryputs("Error: Can't get current working directory\n");elseprintf("Current working directory is:\n%s\n",fpath);puts("____________________________________________________________________");while(--argc >0){if((fp = fopen(*++argv, "r")) == NULL){stradd(errinfo, ERR_INFO_SIZE, exe," can't open the file: ",*argv);errorHandle(ERR_HANDLE_FILE,errinfo);fprintf(stderr,"%s\n",errinfo);continue;}printf("The file \"%s\" opened successfully, and the following is its contents:\n",*argv);printFile(fp,stdout);puts("\n");fclose(fp);}while(1){//ask users whether they want to open other files until they select "N".printf("Do you wanta open other files?(Y or N):");scanf("%c",&slct);while(getchar() != '\n'); //empty the stdinslct=toupper(slct);if(slct == 'N') break;if(slct == 'Y'){printf("Please input the file name:");fname =(char *)malloc(sizeof(*fname)*FILE_NAME_SIZE);scanf("%s",fname);while(getchar() != '\n'); //empty the stdinif((fp = fopen(fname,"r")) == NULL){if(stradd(errinfo, ERR_INFO_SIZE, exe, " can't open the file: ", fname) == EOF){puts("your path is too deep, or the length of the path is too long");break;}errorHandle(ERR_HANDLE_FILE,errinfo);fprintf(stderr,"%s\n",errinfo);}else{printf("The file \"%s\" opened successfully, and the following is its contents:\n",fname);printFile(fp,stdout);puts("");//auto change linefclose(fp);}free(fname);}}puts("");system("pause");}