1、首先打开VC++6.0
2、选择文件，新建
3、选择C++ source file 新建一个空白文档
4、声明头文件#include<stdio.h>#include<stdlib.h>#include<string.h>
5、首先写个加密函数，算法就是简介里说的void EncryptFile(FILE *sfp,FILE *dfp,char pwd){char ch;if(sfp==0||dfp==0){printf("ERROR!\n");return;}while((ch=fgetc(sfp))!=EOF){if((ch>='a')&&(ch<='z')){ch=(ch-'a'+1)%26+'a';ch=ch^pwd;}if((ch>='A')&&(ch<='Z')){ch=(ch-'A'+1)%26+'A';ch=ch^pwd;}fputc(ch,dfp);}}
6、写解密子函数：与加密的过程相反void DecryptFile(FILE *sfp,FILE *dfp,char pwd){char ch;while((ch=fgetc(sfp))!=EOF){if((ch>='a')&&(ch<='z')){ch=ch^pwd;ch=(ch-'a'+25)%26+'a';}if((ch>='A')&&(ch<='Z')){ch=ch^pwd;ch=(ch-'A'+25)%26+'A';}fputc(ch,dfp);}}
7、输出函数，输出文件内容void OutputFile(FILE *fp){char ch;while((ch=fgetc(fp))!=EOF)putchar(ch);}
8、主函数，主要调用这几个函数int main(){/*用户输入的要加密的文件名*/char sfilename[20];/*用户输入加密后保存的文件名*/ char dfilename[20]; /*用来保存密码字符*/ char pwd; FILE *sfp,*dfp; printf("\nPlease input filename to be encrypted:\n"); /*得到要加密的文件名*/ gets(sfilename); /*得到加密后你要的文件名*/printf("input filename to save the encrypted file:\n");gets(dfilename);/*得到加密字符*/printf("Please input your Password:\n");//scanf("%c",&pwd);pwd=getch();/*屏幕以*来表示输入的加密字符*/printf("*\n"); /*以只读方式打开要加密的文件*/if((sfp=fopen(sfilename,"r"))==0){printf("Can't open the file :%s\n",sfilename);exit(0);}/*输出要加密的文件*/printf("\nThe the text of file to be encrypted is:\n");OutputFile(sfp);/*建立加密后的文件*/if((dfp=fopen(dfilename,"w+"))==0){ printf("Can't open or create the file :%s\n",dfilename); //exit(0); }/*文件加密*/fseek(sfp,0L,SEEK_SET); EncryptFile(sfp,dfp,pwd); printf("\n\nEncrypted the file successfully!\n");/*输出加密后的文件*/printf("\nAfter encrypting the text of file is:\n");fseek(dfp,0L,SEEK_SET);OutputFile(dfp);fclose(sfp);fclose(dfp);getch();return 0;}
