2d array in C | Initialisation and Program
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Multidimensional Arrays
C language allows multidimensional arrays.
Syntax of a multidimensional array declaration is:
data_type array_name[size1][size2]...[sizeN];For example, the following declaration creates a three dimensional array of integers:
int multidimension[5][10][4];
The simplest form of multidimensional array is the two-dimensional(2d) array.
A two-dimensional array is a list of one-dimensional arrays.
Two Dimensional Arrays in C and Programs
- An array of arrays is known as a 2D array.
- The two dimensional (2D) array in s also known as a matrix. A matrix can be represented as a table of rows and columns
Syntax:
data_type array_name [ r ][c ];Where data_type can be any valid C data type and array_name will be a valid C identifier. A two-dimensional array can be considered as a table which will have r number of rows and c number of columns.
2D arrays are widely used to solve mathematical problems, image processing, and translation, board games, databases etc.
- Consider your menu card you might have 3 categories i.e starters, main course, and dessert. Under each category, you might have multiple items which belong to it.
- Here, the food category becomes your rows i.e. ‘r’ and items listed under each will be the elements in the columns ‘c’. This leads to 2D array creation, consider A.
| c = 0 | c = 1 | c = 2 | |
| (Starters) r = 0 | A[0, 0] | A[0, 1] | A[0, 2] |
| (Main course) r = 1 | A[1, 0] | A[1, 1] | A[1,2] |
| (Desserts) r = 2 | A[2, 0] | A[2, 1] | A[2, 2] |
Every element is accessed by row and column subscript or index. such as A[0,0] / A[1,0] etc. Thus it is A[r,c]. where r is rows and c is columns.
Initialization of Array elements:
2D Arrays can be initialized in several ways.
First is simply to specify the size of array with array elements.
Example: Here we have initialized an array having 2 rows and 3 columns.
int a[2][3] = {
{1, 3, 1}, /* initializers for row indexed by 0 */
{4, 5, 6} /* initializers for row indexed by 1 */
};
The nested {} braces are optional, however, it improves the readability as it indicated the end of a particular row.
int a[2][3] = { 1, 3, 1, 4, 5, 6 };The above declaration is also equivalent.
int a[2][2] = {1, 2, 3 ,4 } /* Valid declaration*/
int a[][2] = {1, 2, 3 ,4 } /* Valid declaration*/
int abc[][] = {1, 2, 3 ,4 } /* Invalid declaration – you must specify second dimension that is column size*/
int abc[2][] = {1, 2, 3 ,4 } /* Invalid declaration – you must specify second dimension that is column size*/We shall see the reason to specify column size through the next few sections.
