10 examples of using Lambda Functions in C++

  4 mins read  

10 examples of using Lambda Functions in C++

Lambdas solve a problem of readability, expressiveness and practicality. In this article we’ll show you 10 ways you can use it in your code.

Syntax

[](){};

Example 1

This doesn’t do anything, but it’s the most basic way to compile without error.

#include <iostream>

int main(){
  [](){};
  return 0;
}

Example 2

Assigning Lambda Return to a Variable

auto a = [](){};


Example 3

Inserting content into the body of the lambada

auto b = [](){
  std::cout << "I \u2764 Lambda!\n";
};

Example 4

Printing the contents of the lambda

auto c = [](){
  std::cout << "I \u2764 Lambda!\n";
};

c();

Example 5

Passing parameter to Lambda

auto d = []( const char * s ){
  std::cout << s;
};
d("I \u2764 Lambda!\n");

Example 6

Returning defined type

auto e = []()->float {
  return 3.6f;
}; std::cout << "0.9 + e = " << 0.9f + e() << '\n';


Example 7

Passing existing variables

int x, y; x = y = 0;
auto f = [ x, &y ]{
  ++y;
  std::cout << "x e y = " << x << " e " << ++y << '\n';
}; f();
// as y is reference, the value is changed
// x is read-only
// Output: x and y = 0 and 2

Example 8

Running inside std::remove_if and leaving the NUM(123.456.789-00) with only numbers

std::string s("123.456.789-00");
std::vector<std::string> num;
for (int i = 0; i < s.length() ; i++) {
  num.push_back( s.substr(i, 1) );
}

num.erase( std::remove_if( num.begin() , num.end(), []( std::string h )->bool{ 
      return ( h == "-" || h == "." );
    } ) , num.end() );

To see the output: for( auto z : num ){ std::cout << z; }; std::cout << '\n';


Example 9

Calling with direct parameters

int n = [] (int x, int y) { return x + y; }(5, 4);
std::cout << n << '\n';

Example 10

Capturing the clause as a reference

auto indices = [&]( std::string index ){
  std::cout << index << '\n';
};
indices("Starting jobs ...");

That’s all for today, small daily doses that will always keep us in tune with C++!

Add our feed: https://en.terminalroot.com.br/feed to:

Feedly