Using - C
  
 Source Code
  

    
#include<stdio.h>

void main() {
	int size, element, i;
	printf("Enter the size of the Array:  ");
	scanf("%d",&size);
	int arr[size], pos[size], posIndex=0;
	printf("Enter %d Elements:  \n");
	for(i=0; i < size; i++) {
		scanf("%d", &arr[i]);
	}
	system("cls");

//	Displaying Array
	printf("Given Array:  ");
	for(i=0; i < size; i++) {
		printf("%d  ",arr[i]);
	}

	printf("\n\nEnter the element to be searched:  ");
	scanf("%d",&element);

	for(i=0; i < size; i++) {
		if(arr[i] == element) {
			pos[posIndex++] = i+1;
		}
	}
	
	
  if(posIndex != 0) {
  	printf("%d found at position:  ",element);
  	for(i=0; i < posIndex; i++) {
  		printf("%d,  ",pos[i]);
	}
	return; 
  } 
  else {
  	printf("%d not found in this Array!",element);
    return;
  }
}
    

Enter the size of the Array:  6
Enter 6 Elements:
45
89
56
45
12
45

Given Array:  45  89  56  45  12  45

Enter the element to be searched:  45
45 found at position:  1,  4,  6,

        
Using - C++
        
 Source Code
        

        
#include<iostream>
using namespace std;

int main() {
  int size, element;
  cout<< "Enter the size of the Array:  ";
  cin>> size;
  int arr[size] , pos[size] , posIndex=0;
  cout<< "Enter "<< size << " Elements: "<< endl;
  for(int i=0; i < size; i++) {
    cin>> arr[i];
  }
  system("cls");

  //Displaying Array
  cout<< "Given Array:  ";
  for(int i=0; i < size; i++) {
    cout<< arr[i]<< "  ";
  }

  cout<< "\n\nEnter the element to be searched:  ";
  cin>> element;
	

  for(int i=0; i < size; i++) {
    if(arr[i] == element) {
      pos[posIndex++] = i+1;
    }
  }
  
  if(posIndex != 0) {
  	cout<< element<< " found at position:  ";
  	for(int i=0; i < posIndex; i++) {
  		cout<< pos[i]<< ",  ";
	}
	return 1;  
  } 
  else {
  	cout<< element<< " not found in this Array!"<< endl;
    return 0;
  }    
}

Enter the size of the Array:  8
Enter 8 Elements:
12
45
78
12
56
98
12
55

Given Array:  12  45  78  12  56  98  12  55

Enter the element to be searched:  12
12 found at position:  1,  4,  7,