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Concatenating two string using + (plus) operator in C++ STL

C++ STL | concatenating two strings: In this article, we are going to see how we can concatenate two strings using (plus) '+' like other default datatypes?
Submitted by Radib Kar, on February 27, 2019

String as datatype

In C, we know string basically a character array terminated by \0. Thus to operate with the string we define character array. But in C++, standard library gives us the facility to use string as a basic data type like integer.

Example

Here is an example with sample input and output:

Like we define and declare,
int i=5,j=7,k;
Same way, we can do for a string like,
string s1="Include", s2="Help";

Now,
k=i+j; // 12
Same way we can concatenate our two string s1 & s2
string s3=s1+s2;
now s3 is "IcludeHelp" 
string s4=s2+s1;
s4 is "HelpInclude"

Remember, a string variable (literal) need to be defined under "". 'a' is a character whereas "a" is a string.

Header file needed

#include <string>
Or
#include <bits/stdc++.h>

C++ program to concatenate strings using plus (+) operator

#include <bits/stdc++.h>
using namespace std;

int main() {
  string s1, s2, s3, s4;

  cout << "Enter your string1\n";
  cin >> s1;
  cout << "Enter your string2\n";
  cin >> s2;

  cout << "Stings concatenated...\n";
  s3 = s1 + s2;
  cout << "Concat(s1,s2): " << s3 << endl;
  s4 = s2 + s1;
  cout << "Concat(s2,s1): " << s4 << endl;

  return 0;
}

Output

Enter your string1
Include
Enter your string2
Help
Stings concatenated...    
Concat(s1,s2): IncludeHelp
Concat(s2,s1): HelpInclude