#include <cmath>
    double log10( double num );

The log10() function returns the base 10 (or common) logarithm for num. There's a domain error if num is negative, a range error if num is zero.

C++ also provides the following overloaded forms:

    #include <cmath>
    float log10( float num ); // same as log10f() in C99
    long double log10( long double num ); // same as log10l() in C99

Related Topics: log