C Programming Data Structures 1D And 2D Arrays Complete Guide

1D Array Example: Storing and Displaying Numbers

Objective: Create a program to store and display user-entered numbers in a 1D array.

Step-by-Step Example

1. Include Libraries

   • Include standard input-output library for basic I/O functions.

2. Define Constants

   • Define a constant SIZE to determine the size of the array.

3. Declare Variables

   • An integer array (numbers) to store user inputs.
   • A loop counter variable (i).

4. Get User Input

   • Use a for loop to iterate over the array indices, prompting users to enter numbers for each index.

5. Display Output

   • Use another for loop to display the stored numbers.

6. Compile and Run

#include <stdio.h>

#define SIZE 5

int main() {
    int numbers[SIZE];
    int i;

    // Step 4: Get User Input
    printf("Enter %d numbers:\n", SIZE);
    for (i = 0; i < SIZE; i++) {
        printf("Number %d: ", i + 1);
        scanf("%d", &numbers[i]);
    }

    // Step 5: Display Output
    printf("\nYou entered:\n");
    for (i = 0; i < SIZE; i++) {
        printf("Number %d: %d\n", i + 1, numbers[i]);
    }

    return 0;
}

Explanation:

• #include <stdio.h>: This includes the standard input/output library which is required for printf() and scanf() functions.
• #define SIZE 5: Defines a constant named SIZE with the value of 5. This constant determines how many elements the array can hold.
• int numbers[SIZE];: Declares an integer array named numbers that can hold SIZE (5) integers.
• scanf("%d", &numbers[i]);: Reads an integer from the user input and stores it in the array at index i.
• printf("Number %d: %d\n", i + 1, numbers[i]);: Displays the stored number at index i along with its position (i + 1).

2D Array Example: Matrix Addition

Objective: Write a C program to add two matrices using 2D arrays and display the sum matrix.

Step-by-Step Example

1. Include Libraries

   • Include standard input-output library for basic I/O functions.

2. Define Constants

   • Define constants ROW and COL to set the dimensions of the matrices.

3. Declare Variables

   • Two 2D arrays (matrix1, matrix2) to store input matrices.
   • One 2D array (sumMatrix) to store the result of the addition.
   • Indices for loops (i, j).

4. Get User Input for Each Matrix

   • Prompt the user to enter values for both matrices using nested loops.

5. Add Corresponding Elements of Matrices

   • Use nested loops to add corresponding elements of matrix1 and matrix2 and store the result in sumMatrix.

6. Display the Sum Matrix

   • Use nested loops again to print the elements of sumMatrix.

7. Compile and Run

#include <stdio.h>

#define ROW 2
#define COL 3

int main() {
    int matrix1[ROW][COL], matrix2[ROW][COL], sumMatrix[ROW][COL];
    int i, j;

    // Step 4: Get User Input for First Matrix
    printf("Enter elements for first %dx%d matrix:\n", ROW, COL);
    for (i = 0; i < ROW; i++) {
        for (j = 0; j < COL; j++) {
            printf("Element [%d][%d]: ", i + 1, j + 1);
            scanf("%d", &matrix1[i][j]);
        }
    }

    // Step 4: Get User Input for Second Matrix
    printf("\nEnter elements for second %dx%d matrix:\n", ROW, COL);
    for (i = 0; i < ROW; i++) {
        for (j = 0; j < COL; j++) {
            printf("Element [%d][%d]: ", i + 1, j + 1);
            scanf("%d", &matrix2[i][j]);
        }
    }

    // Step 5: Add Corresponding Elements
    for (i = 0; i < ROW; i++) {
        for (j = 0; j < COL; j++) {
            sumMatrix[i][j] = matrix1[i][j] + matrix2[i][j];
        }
    }

    // Step 6: Display the Sum Matrix
    printf("\nSum of two matrices:\n");
    for (i = 0; i < ROW; i++) {
        for (j = 0; j < COL; j++) {
            printf("%d\t", sumMatrix[i][j]);
        }
        printf("\n");
    }

    return 0;
}

Explanation:

• #define ROW 2 and #define COL 3: Set the dimensions of the matrices (both 2x3).
• int matrix1[ROW][COL], matrix2[ROW][COL], sumMatrix[ROW][COL];: Declare three 2D arrays to hold the data for the input matrices (matrix1 and matrix2) and the sum matrix (sumMatrix).
• The first set of nested for loops prompts the user to enter values for matrix1.
• The second set of nested for loops prompts the user to enter values for matrix2.
• The third set of nested for loops performs element-wise addition and stores the results in sumMatrix.
• The final set of nested for loops prints the elements of sumMatrix in a tabulated form.

How to Compile and Run:

Use a C compiler such as GCC. Here's how you can compile and run the programs:

For 1D Array Example:

gcc -o array1d array1d.c
./array1d

For 2D Array Example: