Multidimensional Arrays in C programming

Multidimensional arrays definition

Arrays in C can have multiple subscripts. A common use of multiple-subscripted arrays, which the C standard refers to as multidimensional arrays, is to represent tables of values consisting of information arranged in rows and columns.

To identify a particular table element, we must specify two subscripts:

The first (by convention) identifies the element’s row.
The second (by convention) identifies the element’s column.

Tables or arrays that require two subscripts to identify a particular element are called double-subscripted arrays. Multidimensional arrays can have more than two subscripts.

Array with three rows and four columns, so it’s said to be a 3-by-4 array.

Multidimensional arrays in C — Multidimensional arrays

In general, an array with m rows and n columns is called an m-by-n array.

Defining multidimensional array

A multidimensional array can be initialized when it’s defined, much like a single-subscripted array.

Defining a double-subscripted array int b[2][2]:


    int b[ 2 ][ 2 ] = { { 1, 2 }, { 3, 4 } };

Initializing multidimensional arrays.

The program defines three arrays of two rows and three columns (six elements each).

The definition of array1 provides six initializers in two sublists.
The definition of array2 provides five initializers.
The definition of array3 provides three initializers in two sublists.

Note: Uninitialized elements are assigned the value 0.

   
    // Initializing multidimensional arrays.
    #include <stdio.h>
    void printArray( int a[][ 3 ] ); // function prototype
    
    // function main begins program execution
    int main( void ) {
    
    // initialize array1, array2, array3
    int array1[ 2 ][ 3 ] = { { 1, 2, 3 }, { 4, 5, 6 } };
    int array2[ 2 ][ 3 ] = { 1, 2, 3, 4, 5 };           
    int array3[ 2 ][ 3 ] = { { 1, 2 }, { 4 } };            
    puts( "Values in array1 by row are:" );
    printArray( array1 );
    puts( "Values in array2 by row are:" );
    printArray( array2 );
    puts( "Values in array3 by row are:" );
    printArray( array3 );
    } // end main
    
    // function to output array with two rows and three columns
    void printArray( int a[][ 3 ] ) {    
    size_t i; // row counter 
    size_t j; // column counter
 
    // loop through rows  
    for ( i = 0; i <= 1; ++i ) {
    
    // output column values   
      for ( j = 0; j <= 2; ++j ) {
         printf( "%d ", a[ i ][ j ] );
      } // end inner for      
          
      printf( "\n" ); // start new line of output  
      } // end outer for   
    } // end function printArray


    Output:
    Values in array1 by row are:
    1 2 3
    4 5 6
    
    Values in array2 by row are:
    1 2 3
    4 5 0
    
    Values in array3 by row are:
    1 2 0
    4 0 0

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