C++ Program:

Example:

#include <iostream>
using namespace std;

int main() {
  string s1,reverse;
  cout<<"Enter your string : ";
  getline(cin,s1);
  
  int l=s1.length()-1;
  while(l!=-1) {
    reverse+=s1[l--];
  }
  if(s1==reverse)cout<<"Palindrome String";
  else cout<<"Not a Palindrome String";
  return 0;
}

Output:

  Enter Your string : pop
  Palindrome String

You must know first,

Palindrome String : if a string & reverse of it are equal then the string is Palindrome string

Example :

String: "aba" & its Reverse = "aba" . so it's Palindrome
String: "abc" & its Reverse = "cba" . so it's NOT a Palindrome

//reverse the string
int l=s1.length()-1;
while(l!=-1) {
  reverse+=s1[l--];
}

//check for the Palindrome
if(s1==reverse)