1.加密過程的明文和金鑰可以是任意按鍵輸入的小寫英文字母；解密過程的密文和金鑰可以是任意按鍵輸入的小寫字母
2.給出.cpp檔案原始碼和加解密結果

#include<iostream>
using namespace std;

void main(){
    int k;
    char c;
    int m,n;
    char s[2];
    int j=0;
    cout<<"請輸入您的選擇\n加密單一字元請選1，解密單一字元請選2\n，加密字串請選3，解密字串請選4\n";
    cin>>m;
    switch(m){
        case
 
 1:
            cout<<"請輸入加密的字元c：\n";
            cin>>c;         
            cout<<"請輸入金鑰k：\n";
            cin>>k;
            cout<<"該字元加密為：\n";
            c=c+k;
            cout<<c<<endl;          
            break;
        case 2:
            cout<<"請輸入解密的字元c：\n"
 
;
            cin>>c;         
            cout<<"請輸入金鑰k：\n";
            cin>>k;
            cout<<"該字元加密為：\n";
            c=c-k;
            cout<<c<<endl;          
            break;
        case 3:
            cout<<"請輸入字串長度：n"<<endl;
            cin
 
>>n;
            cout<<"請輸入加密的字元c\n";
            for(j=0;j<n;j++){
                cin>>s[j];      }
                cout<<"請輸入金鑰k：\n";
                cin>>k;
                cout<<"該字元加密為：\n";
                    for(j=0;j<n;j++){
                        s[j]+=k;
                        cout<<s[j];
                    }
                    cout<<"\n";
            break;
        case 4:
            cout<<"請輸入字串長度：n"<<endl;
            cin>>n;
            cout<<"請輸入解密的字元c：\n";
            for(j=0;j<n;j++){
                cin>>s[j];      }
                cout<<"請輸入金鑰k：\n";
                cin>>k;
                cout<<"該字元解密為：\n";
                    for(j=0;j<n;j++){
                        s[j]+=k;
                        cout<<s[j];
                    }
                    cout<<"\n";
            break;
        default:
           cout<<"err";
            break;
    }   
}

執行結果：