C Program to Print Unique Elements in an Array

How to write a C Program to Print Unique Elements in an Array with an example?. Before going into this article Please refer to Array in C article to understand the concept of Array size, index position, etc.

C Program to Print Unique Elements in an Array Example 1

This program asks the user to enter Array Size and array elements. Next, it is going to find out all the Unique elements (non-duplicate elements) present in this array using For Loop.

/* C Program to Print Unique Elements in an Array */
 
#include <stdio.h>
 
int main()
{
	int arr[10], FreqArr[10], i, j, Count, Size;
	
	printf("\n Please Enter Number of elements in an array  :   ");
	scanf("%d", &Size);
	
	printf("\n Please Enter %d elements of an Array  :  ", Size);
	for (i = 0; i < Size; i++)
	{
    	scanf("%d", &arr[i]);
    	FreqArr[i] = -1;
   	}     
 
	for (i = 0; i < Size; i++)
	{
		Count = 1;
		for(j = i + 1; j < Size; j++)
		{
    		if(arr[i] == arr[j])
    		{
    			Count++;
    			FreqArr[j] = 0;
    		}
    	}
    	if(FreqArr[i] != 0)
    	{
    		FreqArr[i] = Count;
		}
	}

 	printf("\n List of Unique Array Elemnts in this Array are : ");
 	for (i = 0; i < Size; i++)
  	{
  		if(FreqArr[i] == 1)
  		{
  			printf("%d\t", arr[i]);
		}		
  	}	     
 	return 0;
}

We already explained the analysis part in our previous C Programming example. Please refer C Program to Count Frequency of each Element in an Array to understand the analysis. And also refer to Array in C article.

Program to Print Unique Elements in an Array Example 2

It is a different version of the above program. Here we are using multiple if statements

/* C Program to Print Unique Elements in an Array */
 
#include <stdio.h>
 
int main()
{
	int arr[10], i, j, k, isUnique, Size;
	
	printf("\n Please Enter Number of elements in an array  :   ");
	scanf("%d", &Size);
	
	printf("\n Please Enter %d elements of an Array  :  ", Size);
	for (i = 0; i < Size; i++)
	{
    	scanf("%d", &arr[i]);
   	}     
 
	for (i = 0; i < Size; i++)
	{
		isUnique = 1;
		for(j = i + 1; j < Size; j++)
		{
    		if(arr[i] == arr[j])
    		{
    			for(k = j; k < Size; k++)
    			{
    				arr[k] = arr[k + 1];
				}
				Size--;
				j--;
				isUnique = 0;
			}
		}
		if(isUnique != 1)
		{
			for(j = i; j < Size - 1; j++)
			{
				arr[j] = arr[j + 1];
			}
			Size--;
			i--;
		}
	}

 	printf("\n List of Unique Array Elements in this Array are : ");
 	for (i = 0; i < Size; i++)
  	{
 		printf("%d\t", arr[i]);
  	}	     
 	return 0;
}

C array unique items output

Please Enter Number of elements in an array  :   10

 Please Enter 10 elements of an Array  :  10 20 10 30 10 40 20 90 5 20

 List of Unique Array Elements in this Array are : 30	40	90	5