C++ compiler error: ambiguous call to overloaded function

Question

string aux;
int maxy,auxx=0;

cin>>aux;

maxy= (int)sqrt(aux.size());

I'm geting:

1> error C2668: 'sqrt' : ambiguous call to overloaded function
1>        could be 'long double sqrt(long double)'
1>        or       'float sqrt(float)'
1>        or       'double sqrt(double)'

Why?

Answer 1

string::size() returns size_t, and sqrt doesn't accept it in any of its versions. So the compiler has to cast, and cannot choose to what - all of them are OK. You have to put explicit cast:

maxy = (int)sqrt((double)aux.size());