Header file for isdigit

Does anyone know the header file to include for isdigit and isalpha?

ctype.h

What does isdigit do

Code:

---

# include<iostream>
using namespace std;

int main ()
{

        char number = '1';

        if (isdigit(number))
          cout << "Yes " << endl;


return 0;
}

---

compile this

isdigit can be found in iostream as well...

Imagine in the above program if the character held in 'number' was an 'a'.

Would "Yes " still be outputted to the screen. Well no... 'a' isn't a digit. '1' is a digit.

Pretty straightforward...

Basically how it's done:

Code:

---

bool isdigit(char c)
{
        if(c >= '0' && c <= '9')
                return true;

        return false;
}

---

Or, even more compactly, you could make a macro:

Code:

---

#define isdigit(c) ((c >= '0' && c <= '9') ? true : false)

---

That's all there is to it