Since I had a little time, and I never used isdigit myself
I made a very basic example of using it.
int main ()
{
char CHAR[]="h"; // then change this to a digit
if (isdigit(CHAR[0]))
{
cout << CHAR[0] << " is a digit" << endl;
cin.get();
}
else
{
cout << CHAR[0] << " is not a digit" << endl;
cin.get();
}
return 0;
}