Printing a 2D Array in Matrix Form in C

How to print a two-dimensional array in C as a neat matrix: nested for loops, a newline after each row, and the %4d width specifier (or a tab) to line the columns up.
C
Programming
Tutorial
Author

Abdullah Al Mahmud

Published

October 20, 2026

A 3 by 3 grid holding 1, 2, 3, 14, 25, 36 and 107, 208, 309. An arrow across the top marks the inner loop over columns, an arrow down the side marks the outer loop over rows, and a terminal on the right shows the same numbers in aligned rows.

The outer loop walks down the rows, the inner loop walks across the columns, and a newline ends each printed row.

To print a 2D array as a matrix, we use nested for loops. The outer loop moves from row to row. The inner loop prints every element of the current row. Right after the inner loop finishes, we print a newline (\n) so the next row starts on a new line.

A complete example

#include <stdio.h>

int main() {
    int rows = 3;
    int cols = 3;

    // 1. Initialise a 2D array
    int matrix[3][3] = {
        {1, 2, 3},
        {14, 25, 36},
        {107, 208, 309}
    };

    printf("The matrix is:\n");

    // 2. Nested loops: rows outside, columns inside
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            printf("%4d", matrix[i][j]);   // width 4 keeps the columns aligned
        }
        printf("\n");                      // end the row
    }

    return 0;
}

Output:

The matrix is:
   1   2   3
  14  25  36
 107 208 309

Key formatting tricks

  • Put printf("\n") after the inner loop but inside the outer loop. If it is missing, the whole matrix prints as one long line of numbers. If it is inside the inner loop, every number lands on its own line.

  • Use a width specifier such as %4d. It reserves at least four characters for each integer, so numbers with one, two or three digits still line up in vertical columns. Choose a width one larger than the longest number, so there is always a gap between columns.

  • A tab is the alternative. Instead of %4d, we can print printf("%d\t", matrix[i][j]);. This gives:

    1 2   3
14    25  36
107   208 309

    Tabs are quick, but how wide they look depends on the terminal, and they can drift out of line when the numbers have different lengths. A width specifier gives the same result everywhere.

Tip

Use %-4d to left-align each number inside its column, or %6.2f for floating-point matrices (width 6, two decimals).

Summary

Task How
Visit every element outer loop over i (rows), inner loop over j (columns)
Start a new row printf("\n"); after the inner loop
Align the columns a width in the format, such as %4d