Remove an element from an array in C

In this topic, we will learn how to delete or remove a particular element from an array in the C programming language. An array is the collection of the same data type elements or items stored in a contiguous memory block. In C programming, an array is derived data that stores primitive data type values like int, char, float, etc.

To delete a specific element from an array, a user must define the position from which the array's element should be removed. The deletion of the element does not affect the size of an array. Furthermore, we should also check whether the deletion is possible or not in an array.

For example, suppose an array contains seven elements, arr[] = {10, 25, 14, 8, 12, 15, 5); and the user want to delete element 8. So, first, the user must define the position of the 8^th element, which is the 4^th, and then check whether the deletion is possible or not. The position of the particular element should not be more than the total elements of an array. Here, we have 7 elements in an array, and the user wants to delete the 8^th position element, which is impossible.

Steps to remove an element from an array

Following is the steps to remove a particular element from an array in C programming.

Step 1: Input the size of the array arr[] using num, and then declare the pos variable to define the position, and i represent the counter value.

Step 2: Use a loop to insert the elements in an array until (i < num) is satisfied.

Step 3: Now, input the position of the particular element that the user or programmer wants to delete from an array.

Step 4: Compare the position of an element (pos) from the total no. of elements (num+1). If the pos is greater than the num+1, the deletion of the element is not possible and jump to step 7.

Step 5: Else removes the particular element and shift the rest elements' position to the left side in an array.

Step 6: Display the resultant array after deletion or removal of the element from an array.

Step 7: Terminate or exit from the program.

Example 1: Program to remove an element from an array using for loop

Let's create a program to delete an element from an array using for loop in the C programming language.

/* program to remove the specific elements from an array in C. */
#include <stdio.h>
#include <conio.h>

int main ()
{
	// declaration of the int type variable
	int arr[50];
	int pos, i, num; // declare int type variable
	printf (" \n Enter the number of elements in an array: \n ");
	scanf (" %d", &num);
	
	printf (" \n Enter %d elements in array: \n ", num);
	
	// use for loop to insert elements one by one in array
	for (i = 0; i < num; i++ )
	{	printf (" arr[%d] = ", i);
		scanf (" %d", &arr[i]);
	}
	
	// enter the position of the element to be deleted
	printf( " Define the position of the array element where you want to delete: \n ");
	scanf (" %d", &pos);
	
	// check whether the deletion is possible or not
	if (pos >= num+1)
	{
		printf (" \n Deletion is not possible in the array.");
	}
	else
	{
		// use for loop to delete the element and update the index
		for (i = pos - 1; i < num -1; i++)
		{
			arr[i] = arr[i+1]; // assign arr[i+1] to arr[i]
		}
		
		printf (" \n The resultant array is: \n");
		
		// display the final array
		for (i = 0; i< num - 1; i++)
		{
			printf (" arr[%d] = ", i);
			printf (" %d \n", arr[i]);
		}
	}
	return 0;
}

Output:

Enter the number of elements in an array:
8

Enter 8 elements in array:
arr[0] = 3
arr[1] = 6
arr[2] = 2
arr[3] = 15
arr[4] = 10
arr[5] = 5
arr[6] = 8
arr[7] = 12
Define the position of the array element where you want to delete:
5

The resultant array is:
arr[0] = 3
arr[1] = 6
arr[2] = 2
arr[3] = 15
arr[4] = 5
arr[5] = 8
arr[6] = 12

In the above program, we input 8 elements for an array arr[] from the user. After that, the user enters the position of the particular element is 5. And then, we checked the defined position by the If statement (if (pos > num + 1)); Here, 5 is less than the (num+1). So the condition is false, and it executes the else block to remove the 5^th position of the element is 10 using for loop and then prints the resultant array.

Example 2: Program to remove the specific character from an array using for loop

Let's consider an example to delete the particular position of the defined character from an array using for loop in the C programming language.

/* program to remove the specific elements from an array in C. */
#include <stdio.h>
#include <conio.h>

int main ()
{
	// declaration of the int type variable
	int arr[50];
	int pos, i, num; // declare int type variable
	printf (" \n Enter the number of elements in an array: \n ");
	scanf (" %d", &num);
	
	printf (" \n Enter %d elements in array: \n ", num);
	
	// use for loop to insert elements one by one in array
	for (i = 0; i < num; i++ )
	{	printf (" arr[%d] = ", i);
		scanf (" %c", &arr[i]);
	}
	
	// enter the position of the element to be deleted
	printf( " Define the position of the array element where you want to delete: \n ");
	scanf (" %d", &pos);
	
	// check whether the deletion is possible or not
	if (pos >= num+1)
	{
		printf (" \n Deletion is not possible in the array.");
	}
	else
	{
		// use for loop to delete the element and update the index
		for (i = pos - 1; i < num -1; i++)
		{
			arr[i] = arr[i+1]; // assign arr[i+1] to arr[i]
		}
		
		printf (" \n The resultant array is: \n");
		
		// display the final array
		for (i = 0; i< num - 1; i++)
		{
			printf (" arr[%d] = ", i);
			printf (" %c \n", arr[i]);
		}
	}
	return 0;
}

Output:

Enter the number of elements in an array:
8
Enter 8 elements in array:
arr[0] = a
arr[1] = b
arr[2] = f
arr[3] = h
arr[4] = e
arr[5] = k
arr[6] = w
arr[7] = p
Define the position of the array element where you want to delete:
4

The resultant array is:
arr[0] = a
arr[1] = b
arr[2] = f
arr[3] = e
arr[4] = k
arr[5] = w
arr[6] = p

Example 3: Program to delete a particular element from an array using the user-defined function

Let's consider an example to demonstrate the deletion of the particular element using the user defined function in the C programming language.

/* program to delete a particular element from an array using user defined function in c. */
#include <stdio.h>
#include <conio.h>

// create user defined function update elements
addElement (int *arr, int num, int pos)
{
	int i;
	// use for loop to update the index
	for (i = pos-1; i < num - 1; i++)
	{
		arr[i] = arr[i+1]; // 
	}
}

// create disp() function to print the input array elements
disp( int arr[], int num)
{
	int i;
	// use for loop to print the resultant array
	for ( i = 0; i < num; i++)
	{
		printf( "\n arr[%d] = %d", i, arr[i]);
	}
}

int main ()
{
	// declaration of the array
	int arr[100];
	int i, num, pos, result;
	
	printf (" Enter the size of the array: ");
	scanf (" %d", &num);
	
	printf (" \n Enter the %d elements in an array: \n", num);
	// use for loop to input the elements one by one
	for (i = 0; i < num; i++)
	{
		printf (" arr[%d] = ", i);
		scanf (" %d", &arr[i]);
	}
	
	// define the position of the element to be deleted from an array
	printf (" Enter the position of the element you want to delete from an array: ");
	scanf (" %d", &pos);
	
// check whether thr defined pos is less than equal to size of array (num) and larger than 0
	if (pos <= num && pos > 0)
	{
		printf (" Array before deletion: \n");
		
		// call disp() function print the array
		disp (arr, num);
		// call addElement() function
		addElement(arr, num, pos);
		
		printf (" \n Array after deletion: \n");
		// disp() function to print the updated array
		disp( arr, num-1);
	}
	return 0;	
}

Output:

Enter the size of the array: 8
Enter the 8 elements in an array:
arr[0] = 2
arr[1] = 4
arr[2] = 6
arr[3] = 8
arr[4] = 10
arr[5] = 3
arr[6] = 9
arr[7] = 12
Enter the position of the element you want to delete from an array: 4
Array before deletion:

arr[0] = 2
arr[1] = 4
arr[2] = 6
arr[3] = 8
arr[4] = 10
arr[5] = 3
arr[6] = 9
arr[7] = 12
Array after deletion:

arr[0] = 2
arr[1] = 4
arr[2] = 6
arr[3] = 10
arr[4] = 3
arr[5] = 9
arr[6] = 12

Example 4: Program to remove the specific element from an array using the pointers

Let's consider an example of deleting the particular element from an array using the pointers and the user defined function in the C programming language.

/* create a program to delete a specific element from an array using pointers in C. */
#include <stdio.h>
#include <conio.h>

// create a function to delete the specific element
void del (int num, int *arr, int index);

int main ()
{
	// declaration of the variables
	int *arr, num, i, index;
	printf (" Define the size of the array: ");
	scanf (" %d", &num);
	
	// use malloc function to dynamic create space for an array
	arr = (int *) malloc (sizeof(int) *num);
	
	printf (" \n Enter %d elements in an array: ", num);
	// use for loop to insert element one by one
	for (i = 0; i < num; i++)
	{
		printf (" \n arr[%d] = ", i);
		scanf (" %d", (arr + i));
	}
	
	// position of the element to be deleted
	printf (" Enter the position of the element to be deleted from an array: ");
	scanf (" %d", &index);
	del (num, arr, index); /* call delete function to delete the position of element and print the resultant array. */
	return 0;
}

// function definition
void del (int num, int *arr, int index)
{
	int i, j;
	// check position of the index
	if (index <= num)
	{
		// use for loop to delete the position of the defined index
		for (i = index - 1; i < num; i++)
		{
			j = i + 1; // assign the elments to j
			*(arr + i) = *(arr + j);
		}
		
		// display the resultant array after deletion of the specific element
		printf (" \n The resultant array after deletion of the array elements are: \n");
		for (i = 0; i < num - 1; i++)
		{
			printf (" arr[%d] = %d \n", i, ( *(arr + i)));
		}
	 } 
	 else
	 {
	 	printf (" \n Please enter correct position.");
	 }
}

Output:

Define the size of the array: 8
Enter 8 elements in an array:
arr[0] = 5
arr[1] = 10
arr[2] = 15
arr[3] = 20
arr[4] = 25
arr[5] = 30
arr[6] = 35
arr[7] = 40
Enter the position of the element to be deleted from an array: 4
The resultant array after deletion of the array elements are:
arr[0] = 5
arr[1] = 10
arr[2] = 15
arr[3] = 25
arr[4] = 30
arr[5] = 35
arr[6] = 40

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