实现Caesar密码（加法密码）加解密

1. 加密过程的明文和密钥可以是任意按键输入的小写英文字母；解密过程的密文和密钥可以是任意按键输入的小写字母

程序：

#include<iostream>

using namespace std;

void main(){

int k;

char c;

int m,n;

char s[2];

int j=0;

cout<<"请输入您的选择\n加密单一字符请选1，解密单一字符请选2\n，加密字符串请选3，解密字符串请选4\n";

cin>>m;

switch(m){

case 1:

cout<<"请输入加密的字符c：\n";

cin>>c;

cout<<"请输入密钥k：\n";

cin>>k;

cout<<"该字符加密为：\n";

c=c+k;

cout<<c<<endl;

break;

case 2:

cout<<"请输入解密的字符c：\n";

cin>>c;

cout<<"请输入密钥k：\n";

cin>>k;

cout<<"该字符加密为：\n";

c=c-k;

cout<<c<<endl;

break;

case 3:

cout<<"请输入字符串长度：n"<<endl;

cin>>n;

cout<<"请输入加密的字符c\n";

for(j=0;j<n;j++){

cin>>s[j]; }

cout<<"请输入密钥k：\n";

cin>>k;

cout<<"该字符加密为：\n";

for(j=0;j<n;j++){

s[j]+=k;

cout<<s[j];

}

cout<<"\n";

break;

case 4:

cout<<"请输入字符串长度：n"<<endl;

cin>>n;

cout<<"请输入解密的字符c：\n";

for(j=0;j<n;j++){

cin>>s[j]; }

cout<<"请输入密钥k：\n";

cin>>k;

cout<<"该字符解密为：\n";

for(j=0;j<n;j++){

s[j]+=k;

cout<<s[j];

}

cout<<"\n";

break;

default:

cout<<"err";

break;

}

}