Section 6.5 Arrays: Multidimensional Arrays

Adapted from: “Beej’s Guide to C Programming” by Brian (Beej Jorgensen) Hall: Beej’s Guide to C Programming: 6.5 Multidimensional Arrays

Brian (Beej Jorgensen) Hall Website

Program for Demonstrating Multidimensional Arrays¶

#include <stdio.h>

int main(void)
{
    int row, col;

    int a[2][5] = {      // Initialize a 2D array
        {0, 1, 2, 3, 4},
        {5, 6, 7, 8, 9}
    };

    for (row = 0; row < 2; row++) {
        for (col = 0; col < 5; col++) {
            printf("(%d,%d) = %d\n", row, col, a[row][col]);
        }
    }
}

Explanation of the Above Code¶

This C program demonstrates the use of a multidimensional array (a 2D array) and how to iterate over it to access and print its elements.

Code Breakdown:¶

Header File:
```
#include <stdio.h>
```
- Includes the standard input/output library to use functions like printf.
Main Function:
```
int main(void)
```
- The entry point of the program.
Variable Declaration:
```
int row, col;
```
- Declares two integer variables, row and col, which will be used as loop counters to iterate through the rows and columns of the array.
2D Array Initialization:
```
int a[2][5] = {
    {0, 1, 2, 3, 4},
    {5, 6, 7, 8, 9}
};
```
- Declares and initializes a 2D array a with 2 rows and 5 columns.
- The first row contains {0, 1, 2, 3, 4}.
- The second row contains {5, 6, 7, 8, 9}.
Nested Loops:
```
for (row = 0; row < 2; row++) {
    for (col = 0; col < 5; col++) {
        printf("(%d,%d) = %d\n", row, col, a[row][col]);
    }
}
```
- Outer Loop: Iterates over the rows of the array (row = 0 to 1).
- Inner Loop: Iterates over the columns of the array (col = 0 to 4).
- printf Statement: Prints the row index, column index, and the value at that position in the array (a[row][col]).
Output:
- The program prints each element of the 2D array along with its row and column indices in the format (row, col) = value.

Example Output:¶

(0,0) = 0
(0,1) = 1
(0,2) = 2
(0,3) = 3
(0,4) = 4
(1,0) = 5
(1,1) = 6
(1,2) = 7
(1,3) = 8
(1,4) = 9

Key Concepts:¶

2D Arrays: Represented as a grid of rows and columns.
Nested Loops: Used to traverse each element of the 2D array.
printf: Displays the indices and values of the array elements.

Similar code found with 1 license type

Compile and Run Code¶

Use Python to Change to Working Directory¶

import os
root_dir = os.getcwd()

code_dir = root_dir + "/" + "C_Code"

os.chdir(code_dir)

build_command = os.system("gcc -o section_6_5_multidimensional_arrays section_6_5_multidimensional_arrays.c")

exec_status = os.system("./section_6_5_multidimensional_arrays")

(0,0) = 0
(0,1) = 1
(0,2) = 2
(0,3) = 3
(0,4) = 4
(1,0) = 5
(1,1) = 6
(1,2) = 7
(1,3) = 8
(1,4) = 9