C++ Program:

Example:

#include <iostream>
using namespace std;

int main() {
  string s1,s2,s3;
  cout<<"Enter your 1st string : ";
  getline(cin,s1);
  cout<<"Enter your 2nd string : ";
  getline(cin,s2);
  
  s3=s1+s2;
  cout<<"Your Joined String : "<<s3;
  return 0;
}

Output:

  Enter your 1st string : Hello
  Enter your 2nd string : World
  Your Joined String : HelloWorld

Use add(+) operator to join any number of string

//s3 stores joined string
  s3 = s1+s2;