code.txt

#include <iostream>

#include<string>

#include<math.h>

using namespace std;

int main()

{

    string a;

    string b="";

    string c="abcdefghijklmnopqrstuvwxyz";

    string d="";

    int n;

    int p=(n/26)+1;

    cout<<"please enter a user key for the encryption"<<endl;

    cin>>n;

    cout<<"please enter a string to encrypt"<<endl;

    cin>>a;

    for(int i=0;i<a.length();i++)

    {
        
for(int j=0;j<c.length();j++)

        {
            
if(a[i]==c[j])
            
{
               
 b=b+c[((j+n)%26)];

                
            }

            
        }
  
      
    }

    cout<<"encrypted string is "<<endl;

    cout<<b<<endl;
    

for(int i=0;i<b.length();i++)

{
    
for(int j=0;j<c.length();j++)

    {

        if(b[i]==c[j])
 
       {
  
          d=d+c[((j-n+p*26)%26)];

            
        }
        
   
 }

    
}

cout<<"decrypted string is"<<endl;

cout<<d;
    

}