Chapter 10: One-Dimensional Arrays in C Language

One-Dimensional Arrays are collections of elements of the same type. They can be used to store multiple data items, and all data elements can be accessed via a single index. The size of an array is fixed and cannot be changed once defined.

1. Definition and Initialization of One-Dimensional Arrays

Definition:

In C language, a one-dimensional array can be defined as follows:

type array_name[size];

• • <span>type</span>: The data type of the array elements (e.g., <span>int</span>, <span>float</span>, <span>char</span>, etc.).
• • <span>array_name</span>: The name of the array.
• • <span>size</span>: The number of elements in the array.

Initialization:

A one-dimensional array can be initialized at the time of definition. For example:

int arr[5] = {1, 2, 3, 4, 5};  // Initialize all elements of the array

If the array is not fully initialized, C language will automatically assign the value <span>0</span> to uninitialized elements.

int arr[5] = {1, 2};  // Initialize the first two elements, remaining elements are 0

Note: The index of the array starts from <span>0</span>, so the index range of the array <span>arr[5]</span> is from <span>arr[0]</span> to <span>arr[4]</span>.

2. Accessing Array Elements

Accessing array elements is done through indices. For example, if we define an array <span>arr[5]</span>, we can access each element via <span>arr[0]</span>, <span>arr[1]</span>, <span>arr[2]</span>, etc.

Example Code:

#include <stdio.h>

int main() {
    int arr[5] = {10, 20, 30, 40, 50};
    
    // Access array elements
    printf("arr[0] = %d\n", arr[0]);  // Output first element
    printf("arr[1] = %d\n", arr[1]);  // Output second element
    printf("arr[2] = %d\n", arr[2]);  // Output third element
    
    return 0;
}

Output:

arr[0] = 10
arr[1] = 20
arr[2] = 30

3. Iterating Through the Array with Loops

Elements in the array can be iterated through using a <span>for</span> loop to print all elements.

Example Code:

#include <stdio.h>

int main() {
    int arr[5] = {1, 2, 3, 4, 5};
    
    // Use loop to iterate through the array
    for (int i = 0; i < 5; i++) {
        printf("arr[%d] = %d\n", i, arr[i]);  // Output array elements
    }
    
    return 0;
}

Output:

arr[0] = 1
arr[1] = 2
arr[2] = 3
arr[3] = 4
arr[4] = 5

4. Arrays as Function Parameters

Arrays can be passed as parameters to functions. Since arrays in C are passed by pointer, it is necessary to pass the size of the array to ensure the function can correctly access all elements.

Example Code:

#include <stdio.h>

// Function definition: pass array and array size
void printArray(int arr[], int size) {
    for (int i = 0; i < size; i++) {
        printf("%d ", arr[i]);
    }
    printf("\n");
}

int main() {
    int arr[5] = {10, 20, 30, 40, 50};
    
    // Call function, passing array and size
    printArray(arr, 5);
    
    return 0;
}

Output:

10 20 30 40 50

5. Common Operations on One-Dimensional Arrays

• • Sum of the Array: The sum of all elements in the array can be calculated using a loop.

#include <stdio.h>

int main() {
    int arr[5] = {1, 2, 3, 4, 5};
    int sum = 0;

    // Calculate the sum of array elements
    for (int i = 0; i < 5; i++) {
        sum += arr[i];
    }

    printf("Sum of array elements = %d\n", sum);
    
    return 0;
}

Output:

Sum of array elements = 15

• • Maximum and Minimum Values of the Array: The maximum or minimum value can be found by iterating through the array.

#include <stdio.h>

int main() {
    int arr[5] = {10, 20, 5, 30, 15};
    int max = arr[0];  // Assume the first element is the maximum
    int min = arr[0];  // Assume the first element is the minimum

    // Iterate through the array to find max and min
    for (int i = 1; i < 5; i++) {
        if (arr[i] > max) {
            max = arr[i];
        }
        if (arr[i] < min) {
            min = arr[i];
        }
    }

    printf("Max value = %d\n", max);
    printf("Min value = %d\n", min);
    
    return 0;
}

Output:

Max value = 30
Min value = 5

6. Summary

• • Definition and Initialization: A one-dimensional array is defined using <span>[]</span> and can be initialized with a fixed set of values.
• • Accessing Array Elements: Elements in the array are accessed via indices, starting from <span>0</span>.
• • Iterating Through the Array: A <span>for</span> loop can be used to iterate through the array and perform operations on each element.
• • As Function Parameters: Arrays can be passed as function parameters, and it is important to pass the size of the array.
• • Common Operations: Operations such as summation, finding maximum, and minimum values can be performed by iterating through the array.