How to pass a 2D array as a parameter In C?

In this below code structure you will understand while passing 2d array as parameter in C programming.

Before passing we must typecast the 2D array while passing the function.

Here below implementation of 2D Array:

#include <stdio.h>
void print(int *arr, int m, int n)
{
	int i, j;
	for (i = 0; i < m; i++)
		for (j = 0; j < n; j++)
			printf("%d ", *((arr+i*n) + j));
}

int main()
{
	int arr[][3] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
	int m = 3, n = 3;

	// We can also use "print(&arr[0][0], m, n);"
	print((int *)arr, m, n);
	return 0;
}

Output:

1 2 3 4 5 6 7 8 9  

What is going on inside the code?

First declaration of an array:

int arr[][3] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};

Then we declare size of row and column like wise

int m = 3, n = 3

At line no. 16 we use print function as parameters passing array pointer with sizes of m and n.

print((int *)arr, m, n);

You can also write above parameter as &a[0][0], m, n as argument in place of (int *)arr, m, n.

The formal parameter declaring as:

void print(int *arr, int m, int n)

The we declare for loop for row and column like

for (i = 0; i < m; i++)
		for (j = 0; j < n; j++)

Here i stands for indexing row and j stands for indexing column.

Then print 2D array elements by this line –

printf("%d ", *((arr+i*n) + j));

Here, *((arr+i*n) + j) print array elements according row and column wise which is similar to

*(*(arr+i)+j) . But return error i.e.

error: invalid type argument of unary ‘*’ (have ‘int’)
    printf("%d ", *(*(arr+i) + j));

So, when write inside function as passing parameter 2D array we write the line in this ways.

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