You must tell the compiler that the printf() function is not the one of your class but from global name space:
void CPrint::printf()
{
::printf("Test");
}
In general it is a bad idea to use names of standard library functions as member function names. With C++ classes, it is common to let member function names begin with an uppercase letter:
class CPrint
{
void Printf();
};
void CPrint::Printf()
{
printf("Test");
}