Check an input positive interger is a prime number or not

/* To check an input positive interger is a prime number */
#include<iostream>
#include<cmath>
using namespace std;

bool isPrime(int);

int main()
{
int y;
cout<<"Please input a positive interger."<<endl;
cin>>y;
if (isPrime(y)  == 1)
cout<<y<<" is a prime number."<<endl;
else
cout<<y<<" is not a prime number."<<endl;
return 0;
}

bool isPrime(int x)
{
int i;

if(x == 1)
{
return 0;
}
else
{
for(i = 2; i <= floor(sqrt(x)); i++)
{
if (x % i == 0)
{
return 0;
break;
}

}
if (i > floor(sqrt(x)))
{
return 1;
}
}
}

kerins-MacBook-Pro:cpp kerin$ ./test4
Please input a positive interger.
1
1 is not a prime number.
kerins-MacBook-Pro:cpp kerin$ ./test4
Please input a positive interger.
2
2 is a prime number.
kerins-MacBook-Pro:cpp kerin$ ./test4
Please input a positive interger.
3
3 is a prime number.
kerins-MacBook-Pro:cpp kerin$ ./test4
Please input a positive interger.
4
4 is not a prime number.
kerins-MacBook-Pro:cpp kerin$ ./test4
Please input a positive interger.
88
88 is not a prime number.