Combine or merge 2 array with loop or function

Question

I'm using Visual 2010. I need to create an array from 2 other arrays, or a function to merge them; I come from PHP so I'm sorry if this is stupid. I tested some loop without success..

a real example could be helpful:

int arrayA[5] = {3,2,1,4,5} 
int arrayB[5] = {6,3,1,2,9}

And the printed expected output of the third arrayC should be :

arrayC {
[3][6]
[2][3]
[2][1]
[4][2]
[5][9]
}

Answer 1

A straightforward approach can look the following way

#include <stdio.h>

#define N   5

int main( void )
{
    int a[N] = { 3, 2, 2, 4, 5 }; 
    int b[N] = { 6, 3, 1, 2, 9 };
    int c[N][2];

    for ( size_t i = 0; i < N; i++ )
    {
        c[i][0] = a[i]; c[i][1] = b[i];
    }

    for ( size_t i = 0; i < N; i++ ) printf( "%d, %d\n", c[i][0], c[i][1] ); 

    return 0;
} 

The program output is

3, 6
2, 3
2, 1
4, 2
5, 9

If you want to write a function that will merge arrays of any size then it can look like

#include <stdio.h>
#include <stdlib.h>

#define N   5

int ** merge( int *a, int *b, size_t n )
{
    int **c = malloc( n * sizeof( int * ) );

    if ( c != NULL )
    {
        size_t i = 0;
        for ( ; i < n && ( c[i] = malloc( 2 * sizeof( int ) ) ); i++ )
        {
            c[i][0] = a[i]; c[i][1] = b[i];
        }

        if ( i != n )
        {
            while ( i-- ) free( c[i] );
            free( c );
            c = NULL;
        }
    }

    return c;
}   

int main( void )
{
    int a[N] = { 3, 2, 2, 4, 5 }; 
    int b[N] = { 6, 3, 1, 2, 9 };
    int **c;

    c = merge( a, b, N );

    if ( c != NULL )
    {
        for ( size_t i = 0; i < N; i++ ) printf( "%d, %d\n", c[i][0], c[i][1] ); 
        for ( size_t i = 0; i < N; i++ ) free( c[i] );
        free( c );
    }

    return 0;
} 

The program output will be the same as shown above.