How to calculate size of array?

In this blog, we need the length of arrays for a variety of actions, including iterating over the array, copying the array, and more. In this post, we’ll look at the many ways to obtain an C array length.

The C array length is fixed and is stated in the declaration of the array. There is no built-in way to determine an array’s size in C. By using C’s built-in techniques or pointers, getting the array’s length requires a little bit of work. There are several approaches to determining C array length. Two methods will be examined in this article:

Thus, the reasoning would be as follows:

I’d want to ask you a query. Could you please provide the length of the following array?

//C sizeof array

You may respond to this question after spending some time on it, but if the array you get is 10 times as large as the one above, it will be challenging and time-consuming. Instead, consider why you would need to manually count the elements when the C language has the sizeof() operator.

So let me show you how to count C Array length of elements using the sizeof() operator.

In C, the sizeof() operator determines the size in bytes of any provided variables or datatypes. Since sizeof() cannot determine the array’s size directly, we must apply the programming logic outlined above to determine its length.

Syntax to calculate C array length using sizeof():

In the above syntax:

Let’s now examine why this algorithm for determining an array’s length is effective:

We divide the size of one array element by the number of array elements to determine the size of the entire array. We then divide the size of the entire array, sizeof(name of the C array), by the size of a single array element, sizeof(name of array[index]), to determine the length of the array. Consequently, we are given the array’s length.

Using sizeof(), a C program may determine the length of an integer array Let’s now have a look at a C program that uses the sizeof() operator to determine the length of an integer array.

Calculate the length of an array using the sizeof() operator in C language. Below is the code Implementation:

Output:

C Program to Calculate the Length of char Array Using sizeof() Let’s now have a look at a C program that uses the sizeof() operator to determine the length of a char array.

Using pointer arithmetic as a solution in C to get the length of an array. In comparison to the sizeof() operator, the approach is straightforward. The length of an array is calculated using the following expression:

Let’s look at some C programs to grasp this better:

Calculate the Length of int Array Using Pointer Arithmetic in C language Below is the code Implementation

Output

Calculate the Length of char Array Using Pointer Arithmetic in C language Below is the code Implementation

Output

For example, when you want to loop through all the elements stored in the array to determine whether a specific value is present.

In this article, you will learn how to find the size of an array using the sizeof() operator.

Let's dive in!

Arrays let you store multiple values under the same variable name.

An array in the C programming language is a collection of items of the same data type. This means you can create an array of only integer values or an array of chars and so on.

To create an array in C, you first need to specify the data type of the values the array will store.

Then, you give the array a name followed by a pair of square brackets, [].

Inside the square brackets, you can specify the size of the array.

So, here is how you would create an array of type int called faveNumbers that will hold 5 integers:

To insert values inside the array during its declaration, use the assignment operator, =, and a pair of curly braces, {}.

Inside the curly braces, enter the items and separate each one with a comma:

The code above creates an array with the name faveNumbers that holds 5 integers, 7, 33, 13, 9, 29.

You could also write the code above as follows:

In the example above, I didn't specify the size of the array.

However, the compiler can tell that the size is 5 since I initialized it with 5 elements.

Something to note here is that you cannot change the size and type of the array once you declare it since they have a fixed length.

C does not provide a built-in way to get the size of an array.

With that said, it does have the built-in sizeof operator, which you can use to determine the size.

The general syntax for using the sizeof operator is the following:

Let's break it down:

Now, let's see this operation in action and break it down into individual steps to see how it works.

Firstly, the sizeof operator returns the total amount of memory allocated to the array in bytes.

However, the code above doesn't calculate the size of the array directly.

You will need some extra programming logic, which will look something like this:

To find the length of the array, you need to divide the total amount of memory by the size of one element - this method works because the array stores items of the same type.

So, you can divide the total number of bytes by the size of the first element in the array.

To access the first element in an array, specify the name and, in square brackets, include 0.

In programming and Computer Science in general, indexing always starts at 0, so the first element in an array will always have an index of 0.

To find the length of the array, you need to divide the total amount of memory by the size of one element - this method works because the array stores items of the same type. So, you can divide the total number of bytes by the size of the first element in the array.