To define a string constant in C++, you have to include the string header library, then create the string constant using this class and the const keyword.
Example
#include<iostream>
#include<string>
int main() {
const std::string MY_STRING = "Hello World!";
std::cout << MY_STRING;
return 0;
}Output
This will give the output −
Hello World!
Note that if you try to reassign a value to this variable it'll cause an error.