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 2Example 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++!
