please help me out A simple substitution cipher can be creat

please help me out.

A simple substitution cipher can be created by shifting a letter n positions in alphabetic order. For example, if the possible characters are the list [A…Za…z], a shift of three would translate A to D and Z to c. The shift is circular so z would shift around to C. The shift value, n, can be positive or negative.

Write c/c++ program that performs this simple substitution cipher. Your c/c++ program should request the user to enter a shift value, followed by one alphabetic character. It should then print the cipher text for that character. Print an appropriate error message if the user enters something other than a letter from the list [A…Za…z].

Solution

#include <stdio.h>

int main()
{
char c;
int a,s;
printf(\"Enter the plaintext character: \");
scanf(\"%c\", &c);
printf(\"Enter the shift: \");
scanf(\"%d\", &s);
  
a = ((c+s)-97)%26 + 97;
printf(\"Ciphertext: %c\ \",a);
}

//----------------------------------------------------------------------------------------------

sh-4.2$ main                                                                                                                                                                    

Enter the plaintext character: a                                                                                                                                                

Enter the shift: 4                                                                                                                                                              

Ciphertext: e