more than one instance of overloaded function matches the argument list

Question

I am getting the above error when I use

double x = log10(100);

I have used it in other class, in the same project and it does not show this err

Answer 1

The error usually indicates that there is more than one overload for the function log10 and that none of them is better than the others for that particular call. For example, the overloads could take float and double: 100 is an int that can be converted to either and the conversions are equivalent, so the compiler cannot determine what the best option is.

You can force the conversion to one of the overloads explicitly:

double x = log10( 100. );    // 100. is a double
float  y = log10( 100f );    // 100f is a float
int i = 100;
double z = log10( static_cast<double>(i) ); // or cast