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;
  }
}

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;
  }
}