C++ Map class emplace example

C++ > Map class > Emplace

Inserts an element constructed in place into a map.

Example 

// ConsoleApplication1.cpp : Defines the entry point for the console application.

//

#include "stdafx.h"

#include <map>

#include <string>

#include <iostream>

using std::endl;

using std::cout;

using std::cin;

int _tmain(int argc, _TCHAR* argv[])

{

       std::map <int, std::string> map;

       auto ret1 = map.emplace(1, "one");

       auto ret2 = map.emplace(2, "two");

       auto tree1 = *ret1.first;

       auto tree2 = *ret2.first;

       cout << "First element is (" << tree1.first << ", " << tree1.second << ")" << endl;

       cout << "Second element is (" << tree2.first << ", " << tree2.second << ")" << endl;

       int ret;

       cin >> ret;

       return ret;

}

#pragma once C# example

C++ > Pragma directives > #pragma once

Specifies that the file will be included only once by the compiler when compiling a source code file, so the build times is reduced.

Example:

HeaderClass.h

#pragma once

// Code placed here is included only once 

namespace Application{

class HeaderClass

{

public:

    HeaderClass();

};

} // namespace Application