Hello ,

I have discovered lambda function in c++. So this blog is going to be about how to use lambda functions a.k.a anonymous function in writing code involving STL algorithms.

I wanted to write about the lambda long ago but got busy on other stuffs.

[capture_list] (parameters) -> return_type
{
   ...
   ...body goes here
   ...
};

Now let go through the syntax and parts of the lambda functions:

[capture lists] => capture list are the variable name from the outer scope which you want to bring to scope of the lambda definition; lamda function has there local scope and variable defined in the caller scope is not available.

e.g
              void func_foo(string useme)
              {
                    usme += "[";
                    auto makeJson = [&useme] () -> std::string { // Bring useme variable in lambda scope
                                     useme += "\"object\":null";
                    };
                   /// I have used auto keyword to hold the lambda definition 
                   /// lambda can be pretty much defined everywhere 

                   makeJson() ; // calling syntax is same as general function
             }

parameters => parameters are the usual parameters in the function definition

void func_foo(string useme)
              {
                    usme += "[";
                    auto makeJson = [&useme] (std::string value) -> std::string { 
                    // Bring useme variable in lambda scope
                                     useme += "\"object\":\"" + value +"\"";
                    };
                   /// I have used auto keyword to hold the lambda definition 
                   /// lambda can be pretty much defined everywhere 

                   makeJson("isnotnull"); 
             }

return_type => return type can be any object or data type defined before As in the above examples "std::string" is the return type

[body_definition] => body definition can be any c++ statement or expression

Well, that was lambda introduced in c++11 and few more features has been added after that.

Feel free to contact and Let me know if there is any error or further edits required.