One Dimensional Array in C

What is One Dimensional Array in C?

A one-dimensional array is a form of data structure used to store components of the same data type, such as characters, floating-point values, or integers, in a continuous block of memory.
A one-dimensional array's components are accessed by their index, which starts at zero and goes up one for each succeeding element. For instance, the first element in an array of integers can be accessed with index 0, the second element with index 1, the third element with index 2, and so on.

One-dimensional arrays are flexible and strong data formats that may be applied to various data storage and manipulation tasks. They are utilised in various applications and are an essential building block of many C programs.

Syntax of One Dimensional Array in C

The following is the syntax for declaring and initialising a one-dimensional array in C:

data_type array_name[array_size] = {value1, value2, value3,…};

 

Parameters:

Following are the parameters used in the above syntax.

• data_type represents the data type of the elements that the array will store.
   
• array_name is the array's name.
   
• array_size is the number of elements the array can hold.
   
• value1, value2, value3,…  are the values of each element in the array.

Example of One-Dimensional Array in C

Here's an example of a one-dimensional array in C that stores integers:

##include <stdio.h>
int main() {
    int numbers[5]; // Declare an array of integers with 5 elements
    // Initialize the array
    numbers[0] = 10;
    numbers[1] = 20;
    numbers[2] = 30;
    numbers[3] = 40;
    numbers[4] = 50;
    // Access and print elements
    for (int i = 0; i < 5; i++) {
        printf("Element %d: %d\n", i, numbers[i]);
    }
    return 0;
}

This program declares and initializes a one-dimensional integer array numbers with 5 elements and prints their values.

Declaration, Initialization and Access of One Dimensional Array in C

Array Declaration

An array in C can be declared by its data type and size. The maximum number of elements that the array can hold denotes its size. 

Let’s see the syntax and example of Array declaration.

Syntax

Data_type name[size];

Example

int arr[4];

Array Initialization

The array can be initialized by either specifying the values at the time of declaration or later. 

The syntax and example of array initialization are:

Syntax 

Data_type name[size] = {value1, value2, value3, ….. , value n};

Example

int arr[4] = { 1, 2, 3, 4 };

Array Accessing

The array can be accessed by referring to its index positions; the indexing of an array usually starts with 0.

The syntax and example of array accessing are:

Syntax

name[index];

Example

int x = arr[2];

Rules for Declaring a One Dimensional Array in C

Before using an array variable in a program, it must be declared. We can do the declaration by the below rules:

• A data type (int, float, char, double, etc.), variable name, and subscript must be specified in the declaration.
   
• The subscript represents the array's size. For example, when the size is set to 10, programmers can store ten elements.
   
• An array index always begins with 0. For example, if an array variable is declared as array[10], the index can take values between 0 and 9.
   
• Each array element is kept in its memory location.

How to Initialize One Dimensional Array in C? 

There are various approaches to initialising a one-dimensional array in C. 

Related Article - How do you Initialize an Array in C

Compile-Time Initialization

The compile time initialization is used to initialize the array with the fixed values at the time of declaration. It's called compile time since the array is initialized before the program is compiled.

An example of initializing an array named arr with 5 integers is:

Example

int arr[5] = { 1, 2, 3, 4, 5 };

Run-Time Initialization

The run-time initialization is used to initialize the array with values at run-time when the program is in the execution phase. 

An example of initializing the array by taking input from users at run time using the scanf() function is:

Example

int arr[5];
for (int i = 0; i < 5; i++) {
	scanf("%d", &arr[i]);
}

Copying One-Dimensional Arrays in C

We can copy the contents of a one-dimensional array into another array using inbuilt functions or loops in C. Let’s discuss them one by one.

Using Loops

We can use any of the while, do-while, or for loops to copy the contents. The basic idea is to traverse the original array and copy the contents to the duplicate array. 

Let’s see an example of the same.

Implementation

#include <stdio.h>
#include<string.h>

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

	printf("The original array is: ");
	for (int i = 0; i < 5; i++) {
		printf("%d ", arr[i]);
	}
	printf("\n");

	int duplicate[5];

	for (int i = 0; i < 5; i++) {
		duplicate[i] = arr[i];
	}

	printf("The duplicate array is: ");
	for (int i = 0; i < 5; i++) {
		printf("%d ", duplicate[i]);
	}
	printf("\n");
	return 0;
}

Output

The original array is: 1 2 3 4 5 
The duplicate array is: 1 2 3 4 5

Using Built-in Functions

The string.h library contains a function memcpy(), which can be used to copy the content of an array. It takes 3 arguments, the destination array, the source array and the size of the source array.

Let’s understand it with an example.

Implementation

#include <stdio.h>
#include<string.h>

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

	printf("The original array is: ");
	for (int i = 0; i < 5; i++) {
		printf("%d ", arr[i]);
	}
	printf("\n");

	int duplicate[5];

	memcpy(duplicate, arr, sizeof(arr));

	printf("The duplicate array is: ");
	for (int i = 0; i < 5; i++) {
		printf("%d ", duplicate[i]);
	}
	printf("\n");
	return 0;
}

Output

The original array is: 1 2 3 4 5 
The duplicate array is: 1 2 3 4 5 

Also read,  Short int in C Programming

Important Points to Remember About Array in C

• Fixed Size: Arrays have a fixed size determined at declaration.
• Zero-Based Index: Array elements are accessed using indices starting from 0.
• Homogeneous: Arrays store elements of the same data type.
• Declaration: Declare an array by specifying its data type and size (e.g., int numbers[5]).
• Initialization: You can initialize arrays at declaration or later using curly braces (e.g., int numbers[5] = {1, 2, 3, 4, 5}).
• Accessing Elements: Access elements using square brackets (e.g., numbers[2]).
• Bound Checking: C arrays do not have built-in boundary checks, so be cautious to avoid accessing out-of-bounds indices.
• Passing to Functions: Arrays are passed to functions by reference, allowing modifications within the function to affect the original array.

Frequently Asked Questions

What is single dimensional array in C with example?

A single-dimensional array in C stores elements in a linear sequence. Example: int numbers[5] = {1, 2, 3, 4, 5}; stores 5 integers in an array named "numbers."

Can we change the size of a one-dimensional array once it is declared in C?

No, once declared, we cannot change the size of a one-dimensional array in C. We can, however, make a new array of varying sizes and copy the elements from the original array to the new one.

How can we access elements of a one-dimensional array in C?

In C, one-dimensional arrays enable element access by providing the array name followed by an index value in square brackets. Indexing starts at 0 and goes up to size-1.

Can we initialise a one-dimensional array with values of different data types in C?

In C, one-dimensional arrays can be initialized statically at compile-time or dynamically at runtime. When declaring such arrays, use square brackets to specify the data type, array variable name, and size

Can we pass a one-dimensional array to a function in C as an argument?

Function arguments can accept both one-dimensional arrays and multidimensional arrays.

Conclusion

This article briefly discussed the topic of the one-dimensional array in C. We discussed its definition, syntax, declaration, and initialisation. We hope this article helped you understand the topic of the one-dimensional array in C.

For further reading, refer to our articles on similar topics:

• Single-Dimensional Arrays
• Difference Between One-Dimensional And Two-Dimensional Array
   

Recommended problems -

• Shortest subarray with a sum of at least k
• Maximum sum subarray of size k
• Max circular subarray sum
• Subarray sums divisible by k

 

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