Program to find if a Number is Prime or Not Prime in C++ , OOP

Q: Write a function, which accept an integer value as argument, display the message if the integer value is prime otherwise display it is not prime. Write a main program which will call the function by passing an integer value the function. 

Answer : 

#include<iostream>

using namespace std;

int prime(int NUM);

int main(){

     int num, cond;

    cout<<"Enter Number : ";

    cin>>num;

    cond = prime(num);

    if(cond==2){

    cout<<num<<"It is Prime Number ";

}else {

cout<<num<<"It is Not a Prime Number";

}

    return 0;

}

int prime(int NUM){

int a=0;

if(NUM>1){

for(int i=0; i<=NUM; i++){

if(NUM % i==0){

a++;

}else {

a=a;

}

}

}

return (a);

}