Two-dimensional Array (2D Array)

Algortimy Content of the lesson:

Principle of 2D Array
Writing 2D Array to Screen
Filling in 2D Array

Principle of 2D Array

A 2D array uses another dimension compared to a standard array. You can see an illustration of an empty 2D array (5x5):

A perfect analogy is a list of squared paper with dimensions m x n squares.

Writing 2D Array to Screen

Take a look at writing an empty 2D array to screen:

Writing an empty 2D array to screen


            #include "stdafx.h"
                
#define M 2
#define N 4

int _tmain(int argc, _TCHAR* argv[])
{
	int p[M][N];
    int radek, sloupec;
    
    for (radek = 0; radek < M; radek++)
    {
    	for (sloupec = 0; sloupec < N; sloupec++)
        {
        	p[radek][sloupec] = 0;
        }
    }
    
    for (radek = 0; radek < M; radek++)
    {
    	for (sloupec = 0; sloupec < N; sloupec++)
        {
        	printf("%d ", p[radek][sloupec]);
        }
    }

	fflush(stdin);
    getchar();
    return 0;
}

Numbers are written all together and you absolutely cannot see that this is a 2D array. To illustrate this fact you have to use another writeln command after writing every line to console.

Writing an empty 2D array to screen


#include "stdafx.h"
                
#define M 2
#define N 4

int _tmain(int argc, _TCHAR* argv[])
{
	int p[M][N];
    int radek, sloupec;
    
    for (radek = 0; radek < M; radek++)
    {
    	for (sloupec = 0; sloupec < N; sloupec++)
        {
        	p[radek][sloupec] = 0;
        }
    }
    
    for (radek = 0; radek < M; radek++)
    {
    	for (sloupec = 0; sloupec < N; sloupec++)
        {
        	printf("%d ", p[radek][sloupec]);
        }
        printf("\n");
    }

	fflush(stdin);
    getchar();
    return 0;
}

Filling 2D Array

In the following examples we will try to fill a square 2D array (dimensions set to nxn) with numbers. To be able to write it to screen, choose the dimensions to 10x10 items.

The basic algorithm to fill an array with numbers


#include "stdafx.h"

#define M 10
#define N 10

int _tmain(int argc, _TCHAR* argv[])
{
	int p[M][N];
    int radek, sloupec;
                
	for (radek = 0; radek < M; radek++)
    {
    	for (sloupec = 0; sloupec < N; sloupec++)
        {
        
        }
    }
    
    for (radek = 0; radek < M; radek++)
    {
    	for (sloupec = 0; sloupec < N; sloupec++)
        {
        	printf("%d ", p[radek][sloupec]);
        }
        printf("\n");
    }
	
    fflush(stdin);
    getchar();
    return 0;
}