Lambdas

Invocation

#include <algorithm>
#include <array>
#include <string>
#include <functional>
#include <iostream>

using namespace std ;



int main()
{
  int num1 = 1;
  int num2 = 2;

  auto lambda1Obj = [] (int a, int b) {
      return a + b;
       }  ;

  cout << "lambda1Obj invoked: " << lambda1Obj( 5,6) << endl ;

  //invoked right away
  auto sum = [] (int a, int b) {
    return a + b;
  } (num1, num2);

  cout << "The sum of " << num1 << " and " << num2
  << " is " << sum << endl   ;



}

Output:
$ g++ lambdas14.cpp ; ./a.exe
lambda1Obj invoked11
The sum of 1 and 2 is 3


We have seen how the lambda expression can be evaluated.
We can invoke it inline or we can assign it to a lambda
object and then call the lambda as shown in the code above.

  auto lambda1Obj = [] (int a, int b) {
      return a + b;
       }  ;

  cout << "lambda1Obj invoked: " << lambda1Obj( 5,6) << endl ;

The above snippet shows the lambda object being created. We can
also have the expression executed at the point of definition with
the below snippet.

  //invoked right away
  auto sum = [] (int a, int b) {
    return a + b;
  } (num1, num2);

  cout << "The sum of " << num1 << " and " << num2
  << " is " << sum << endl   ;

Here the variable "sum" is of type integer. The lambda
expression gets executed with arguments "num1" and "num2" .