VC++ 凯撒密码加密解密程序

#include<fstream> // 文件流 #include<iostream> // 标准流 #include<string> // 字符串对象 using namespace std; // 使用std名字空间 void main() { string choose; L1: cout<<"1、encrytion"<<endl<<"2、decrytion"<<endl<<"3、quit"<<endl<<"what do you want to do?"<<endl; cin>>choose; if(choose=="1")//加密 { //新建一个加密文件在d/encrytion.txt ifstream inFile; inFile.open("d://test.txt"); // 打开文件 string str; // 行字符串缓存 if(inFile.is_open()) { // 如果创建成功，填入内容 //在输入内容之前，首先输入加密密钥（介于1和25之间的一个整数） int Ek; cout<<"please put in your encrytion key(the number between 1 and 25):"<<endl; cin>>Ek; cout<<endl; if(Ek>=1&&Ek<=25) { ofstream outFile; outFile.open("d://encrytion.txt"); // 创建文件 if(outFile.is_open()) { // 若成功打开文件 while(!inFile.eof()) { // 若未到文件结束 getline(inFile, str, '\n'); // 读取一行内容，并存入缓存str中，'\n'表示一行结束的回车符 //cout << str << endl; // 把缓存内容输出到屏幕 for(int i=0;str[i]!=NULL;i++) { if(str[i]>=65&&str[i]<=90) str[i]=(str[i]+Ek-65)%26+65; else if(str[i]>=97&&str[i]<=122) str[i]=(str[i]-97+Ek)%26+97; else str[i]=str[i]; outFile<<str[i]; } outFile<<endl; } cout<<"The encrytion is sucessd,"<<endl<<" the encrytion file is in d:// ,called encrytion.txt!"<<endl; } else cout<<"we coun't built the encrytion.txt"<<endl; outFile.close(); // 关闭文件 } else cout<<"The number you put is wrong!"<<endl; } else cout<<"we can't find the file called test.txt in d:/"<<endl; inFile.close(); } else if(choose=="2")//解密 { int temp=0; ifstream inFile; inFile.open("d://test.txt"); if(inFile.is_open()) { string str; int a[27]={0};//0--25用来存储a（A）-z（Z）的个数，26用来存储总字符的个数。 while(!inFile.eof()) { getline(inFile,str,'\n'); for(int i=0;str[i]!=NULL;i++) { switch(str[i]) { case 'a':{a[0]++;a[26]++;break;} case 'A':{a[0]++;a[26]++;break;} case 'b':{a[1]++;a[26]++;break;} case 'B':{a[1]++;a[26]++;break;} case 'c':{a[2]++;a[26]++;break;} case 'C':{a[2]++;a[26]++;break;} case 'd':{a[3]++;a[26]++;break;} case 'D':{a[3]++;a[26]++;break;} case 'e':{a[4]++;a[26]++;break;} case 'E':{a[4]++;a[26]++;break;} case 'f':{a[5]++;a[26]++;break;} case 'F':{a[5]++;a[26]++;break;} case 'g':{a[6]++;a[26]++;break;} case 'G':{a[6]++;a[26]++;break;} case 'h':{a[7]++;a[26]++;break;} case 'H':{a[7]++;a[26]++;break;} case 'i':{a[8]++;a[26]++;break;} case 'I':{a[8]++;a[26]++;break;} case 'j':{a[9]++;a[26]++;break;} case 'J':{a[9]++;a[26]++;break;} case 'k':{a[10]++;a[26]++;break;} case 'K':{a[10]++;a[26]++;break;} case 'l':{a[11]++;a[26]++;break;} case 'L':{a[11]++;a[26]++;break;} case 'm':{a[12]++;a[26]++;break;} case 'M':{a[12]++;a[26]++;break;} case 'n':{a[13]++;a[26]++;break;} case 'N':{a[13]++;a[26]++;break;} case 'o':{a[14]++;a[26]++;break;} case 'O':{a[14]++;a[26]++;break;} case 'p':{a[15]++;a[26]++;break;} case 'P':{a[15]++;a[26]++;break;} case 'q':{a[16]++;a[26]++;break;} case 'Q':{a[16]++;a[26]++;break;} case 'r':{a[17]++;a[26]++;break;} case 'R':{a[17]++;a[26]++;break;} case 's':{a[18]++;a[26]++;break;} case 'S':{a[18]++;a[26]++;break;} case 't':{a[19]++;a[26]++;break;} case 'T':{a[19]++;a[26]++;break;} case 'u':{a[20]++;a[26]++;break;} case 'U':{a[20]++;a[26]++;break;} case 'v':{a[21]++;a[26]++;break;} case 'V':{a[21]++;a[26]++;break;} case 'w':{a[22]++;a[26]++;break;} case 'W':{a[22]++;a[26]++;break;} case 'x':{a[23]++;a[26]++;break;} case 'X':{a[23]++;a[26]++;break;} case 'y':{a[24]++;a[26]++;break;} case 'Y':{a[24]++;a[26]++;break;} case 'z':{a[25]++;a[26]++;break;} case 'Z':{a[25]++;a[26]++;break;} // default:a[26]++; } } }//全部数据统计结束！ for(int i=1;i<26;i++) if(a[i]>a[temp]) temp=i; cout<<"文件中各个字符出现的概率："<<endl; for(i=0;i<26;i++) cout<<char(65+i)<<"："<<a[i]*0.1/a[26]*10<<'\t'; cout<<endl; if(a[temp]>a[26]*0.100&&a[temp]<a[26]*0.140&& //e a[(temp+22)%26]>0.06*a[26]&&a[(temp+22)%26]<0.09*a[26]&& //a a[(temp+10)%26]>0.06*a[26]&&a[(temp+10)%26]<0.09*a[26]&& //o a[(temp+4)%26]>0.06*a[26]&&a[(temp+4)%26]<0.09*a[26]&& //i a[(temp+1)%26]>0.015*a[26]&&a[(temp+1)%26]<0.028*a[26]&& //f a[(temp+2)%26]>0.015*a[26]&&a[(temp+2)%26]<0.028*a[26]&& //g a[(temp+20)%26]>0.015*a[26]&&a[(temp+20)%26]<0.028*a[26]&& //y a[(temp+19)%26]<0.01*a[26]&& //x a[(temp+12)%26]<0.01*a[26]&& //q a[(temp+21)%26]<0.01*a[26] //z )//符合其他概率要求，则密钥确定 { temp=(temp-4+26)%26;//计算密钥 cout<<"文件已解密"<<endl<<"解密密钥: "<<temp<<endl; } else cout<<"内容太少，无法解密！"<<endl; cout<<"文件中共出现英语字母个数："<<a[26]<<endl; } else cout<<"we can't find the file called test.txt in d:/"<<endl; inFile.close(); if(temp!=0) { ifstream inFile2; inFile2.open("d://test.txt"); if(inFile2.is_open()) { string str; ofstream outFile; outFile.open("d://decrytion.txt"); // 创建文件 if(outFile.is_open()) { while(!inFile2.eof())//inFile文件重新打开！ { getline(inFile2,str,'\n'); for(int i=0;str[i]!=NULL;i++) { if(str[i]>=65&&str[i]<=90) str[i]=(str[i]-65-temp+26)%26+65; else if(str[i]>=97&&str[i]<=122) str[i]=(str[i]-97-temp+26)%26+97; else str[i]=str[i]; outFile<<str[i]; } outFile<<endl; } cout<<"解密成功，解密文件decrytion.txt放在D盘下"<<endl; inFile.close(); } else cout<<"we can't build the file called decrytion.txt in d://!"<<endl; } else return; } else return; } else if(choose=="3")//退出 { return; } else { cout<<"you put the wrong number!"<<endl; goto L1; } }