Checking if a number is perfect square?

Question

I think there is a precision problem with the following code:

bool isPerfectSquare(long long n){
    long long squareRootN=(long long)(sqrt(n)+0.5);

    return          


        

Answer 1

You could use a range for your return boolean, although it may lead to unprecise outputs depending on how stringent your requirements are:

double threshold = 0.01;

return (squareRootN*squareRootN > n-threshold) && (squareRootN*squareRootN < n+threshold);