2 Dimensional Array in C

January 18, 2023

2D Array

2D Array is defined as the continuous block of memory in which a similar data type is stored. 2D Array indexing starts with size 0 and ends with size -1. The size of the 2D array is fixed and it is stored in static memory.

2 Dimensional Array in C

Syntax: 

 data_type array_name [i][j]

Representation of 2D Array

Array Declaration

Declaration of 2D Array consists of any data type and it can be declared by any random name or any random variable.

Syntax:

int arr[3][5];

// Here int is the data type of array.
// arr is the name of array.
// 3 is the size of row and 5 is the size of column of an array.

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Multi-dimensional arrays

Passing array as a parameter

Strings in C

Array v/s string

Program for Reversing a String

Array Initialization

In 2D Array, All the elements consist of garbage value at initial time but it can be explicitly initialized during declaration.

Syntax:

 int Arr[i][j] = {value 1, value 2, value 3,…,value ij}

Accessing of elements in 2D Array:

In 2D Array elements are accessed by putting the array name and index value inside square brackets.

Syntax:

<arr_name>[index];

Rules for 2D Array Declaration:

  • In 2D array we must have to declare the array variable.
  • 2D Array stores the data in contiguous memory locations.
  • 2D Array  should be a list of similar data types.
  • The size of the 2D array should be fixed.
  • 2D Array should be stored in static memory.
  • 2D Array indexing starts with size 0 and ends with size -1.
  • In 2D Array declaration of array size within the bracket is not necessary.
  • In 2D Array it must include the variable name  and data type while declaring any arrays .
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Example 1

Run

#include <stdio.h>
int main() {
    int arr[3][3] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
    for (int i = 0; i < 3; i++) {
        for (int j = 0; j < 3; j++) {
            printf("%d ", *(*(arr + i) + j)); 
        }
        printf("\n");
    }
    return 0;
}

Output:

1  2  3
4  5  6
7  8  9

Example 2

Run
#include
int main() {
    int arr[3][3] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
    printf("The even elements in the 2d array are : ");
    for (int i = 0; i < 3; i++) {
        for (int j = 0; j < 3; j++) {
            if(arr[i][j]%2==0) printf(" %d ", *(*(arr + i) + j));
        }
    }
    return 0;
}

Output

The even elements in the 2d array are : 2 4 6 8

Example 3

Run

#include <stdio.h>
int main() {
    int arr[3][3] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
    for (int i = 0; i < 3; i++) {
        for (int j = 0; j < 3; j++) {
            if(i==0 && j==0){
            printf("The first element of 2d array is : %d\n ", *(*(arr + i) + j)); 
            }
            else if(i==2 && j==2){
            printf("The last element of 2d array is : %d ", *(*(arr + i) + j)); 
            }
        }

    }
    return 0;
}

Output

The first element of 2d array is : 1
The last element of 2d array is : 9

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