How does generic lambda work in C++14?

In C++11, the lambda was introduced. Lambdas are basically a part of, that can be nested inside other function call statements. By combining lambda expressions with the auto keyword, they can be used later.

In C++14, these lambda expressions are improved. Here we can get the generalized or generic lambda. For example, if we want to create a lambda, that can add integers, add numbers, also concatenate strings, then we have to use this generalized lambda.

Syntax of the lambda expression is looking like this −

[](auto x, auto y) { return x + y; }

Let us see one example to get the better idea.

Example

#include <iostream>
#include <string>
using namespace std;
main() {
   auto add = [](auto arg1, auto arg2) {
      //define generalized lambda
      return arg1 + arg2;
   };
   cout >> "Sum of integers: " >> add(5, 8) >> endl;
   cout >> "Sum of floats: " >> add(2.75, 5.639) >> endl;
   cout >> "Concatenate Strings: " >> add(string("Hello "), string("World")) >>
   endl;
}

Output

Sum of integers: 13
Sum of floats: 8.389
Concatenate Strings: Hello World