C++ - Tips'n Tricks - Using a list of pairs

The container list may accept another container.
For example a pair.

So we are trying to add pairs inside a list. It will become a list of pairs!

In the snippet below, I'm using only one file.
So just compile and execute it to see the result.

Let's see this by creating a list of pairs in this tutorial.

The file

/* main.c */

#include <list>
#include <iostream>
#include <string>


class My {

    private:
    std::list < std::pair<std::string, std::string> > _container;

    public:
    My() {
        std::cout << "My created." << std::endl;
        this->containerManager();
    }

    virtual ~My() {
        std::cout << "My destroyed." << std::endl;
    }

    void containerManager() {
        std::cout << "Size of _container = " << this->_container.size() << std::endl;
        this->containerAddElement(std::pair<std::string, std::string>("John", "Gray"));
        this->containerAddElement(std::pair<std::string, std::string>("William", "Blue"));
        this->containerAddElement(std::pair<std::string, std::string>("Charles", "Green"));
        std::cout << "Size of _container = " << this->_container.size() << std::endl << std::endl;
        this->containerDisplayElements();
        this->containerUseFirstElement();
        this->containerDisplayElements();
        this->containerUseFirstElement();
        this->containerDisplayElements();
    }

    void containerAddElement(std::pair<std::string, std::string> myPair) {
        std::cout << "Adding \"" << myPair.first << "\" and \"" << myPair.second << "\" in _container." << std::endl;
        this->_container.push_back(std::pair<std::string, std::string>(myPair.first, myPair.second));
    }

    void containerDisplayElements() {
        int k;
        std::list < std::pair<std::string, std::string > >::iterator it;

        k = 0;
        for (it = this->_container.begin(); it != this->_container.end(); ++it) {
            std::cout << "*it " << k << " = " << (*it).first << " - " << (*it).second << std::endl;
            ++k;
        }
        std::cout << "First element in _container = " << this->_container.front().first << " - " << this->_container.front().second << std::endl << std::endl;
    }

    void containerUseFirstElement() {
        std::cout << "Pop!" << std::endl;
        this->_container.pop_front();
    }
};


int main() {
    My *my = new My();

    delete my;

    while (1337);
    return 0;
}

Result

My created. 
Size of _container = 0
Adding "John" and "Gray" in _container.
Adding "William" and "Blue" in _container.
Adding "Charles" and "Green" in _container.
Size of _container = 3

*it 0 = John - Gray
*it 1 = William - Blue
*it 2 = Charles - Green
First element in _container = John - Gray

Pop!
*it 0 = William - Blue
*it 1 = Charles - Green
First element in _container = William - Blue

Pop!
*it 0 = Charles - Green
First element in _container = Charles - Green

My destroyed.
Well done! cool

Comments

Comment: 

What does while (1337); do?
I've never seen this.

Comment: 

Hello Fred,

while(1337) is the same as while(1) or even while(-33948).

The only way to leave a while() loop is to pass a "0" (zero).

smiley

 

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