mono alphabetic Cipher substitution technique

AIM:

To implement a program for encrypting a plain text and decrypting a cipher text using

mono alphabetic Cipher substitution technique.

CODE:

#include<iostream>
#include<conio.h>
#include<stdio.h>
#include<string.h>
void encryption();
void decryption();
char pt[50],ct[50],ch;
char alpha[26]={'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
char sub[26]={'q','w','e','r','t','y','u','i','o','p','a','s','d','f','g','h','j','k','l','z','x','c','v','b','n','m'};
int i,j;
using namespace std;
int main()
{

int choice;
cout<<"****Monoalphabetic Cipher Technique***";
cout<<"\n\n1. Encryption \t2. Decryption";
cout<<"\nEnter your choice: ";
cin>>choice;
 switch(choice)
 {
  case 1: //Encryption
   encryption();
   break;
  case 2: //Decryption
   decryption();
   break;
  default: //Wrong Input
    cout<<"\nIncorrect choice. Try again!!";
    break;
 }
cout<<"\n\nThank You.";
getch();
}

void encryption()
{
cout<<"\nEnter plain text: ";
cin>>pt;
for(i=0;i<strlen(pt);i++)
{
 ch = pt[i];
 for(j=0;j<26;j++)
 {
  if(alpha[j]==ch)
  {
   ct[i]=sub[j];
  // break;
  }
 }
}
ct[i]='\0';
cout<<"\nThe cipher text is: ";
for(i=0;i<strlen(pt);i++)
  cout<<ct[i];
}
void decryption()
{
cout<<"\nEnter cipher text: ";
cin>>ct;
for(i=0;i<strlen(ct);i++)
{
 ch=ct[i];
 for(j=0;j<26;j++)
 {
  if(sub[j]==ch)
  {
   pt[i]=alpha[j];
   break;
  }
 }
}
pt[i]='\0';
cout<<"\nThe plain text is: ";
for(i=0;i<strlen(ct);i++)
  cout<<pt[i];
}

OUTPUT:-