C++ variable overloading ambiguity

Question

For the following line of code:

for (int i = 1; i <= var; i++) { double inc = (14.0) - double(ceil(log10(i)))};

I keep getting the error

Overloading ambiguity between "std::log10(double)" and "std::log10(float)"

I've also tried casting both inc and ceil(log10(i)) to float to no avail. Thoughts?

Answer 1

What makes you think casting inc or ceil will help? The compiler is telling you that it can't figure out whether you want log10(float) or log10(double) . You need to make that clear to the compiler

double inc = (14.0) - double(ceil(log10((float)i)));

or

double inc = (14.0) - double(ceil(log10((double)i)));

Answer 2

Overloading ambiguity between "`std::log10(double)`" and "`std::log10(float)`"
                                           ^^^^^^                     ^^^^^

As @John3136 commented the error is referring to the input of the log10 function. In this case that is the i variable which is an int type. Since, int is neither a float or a double and both conversions are equally viable the compiler doesn't know which to choose. Therefore, you have to explicitly select one. For example:

std::log10(static_cast<float>(i));