[RESOLVED] Macros

Firstly, this is a macro, yeah?

Code:

---

#define MIN 7;

---

Secondly, why doesn't this work if all these "macros" are just numbers?

Code:

---

#include <iostream>
#include <string>
using namespace std;

#define MIN 7;
#define MAX 8;

int main()
{
        cout << MIN * MAX; //this doesn't work
       
        cout << 7 * 8;
}

---

Your macro is turning MIN into 7;
#define statements do not ordinarily end in a semi-colon. Additionaly your main should return something.

The correct code is

Code:

---

#include <iostream>
#include <string>

using namespace std;

#define MIN 7
#define MAX 8

int main()
{
        cout << MIN * MAX; // works now!!
        cout << 7 * 8;
        return 0;
}

---

Regards
Alan

Hi.

The first thing is that you have semi-colons at the end of your define statements. Another thing that is important to know is that in several (or most) of the cases, there's a better approach than using macros. For instance, in this particular case, you could have this:

Code:

---

#include <iostream>
#include <string>

using namespace std;

const int MIN = 7;
const int MAX = 8;

---

To clear things further, consider what happens with the first code listing. MIN is defined as 7; and MAX is defined as 8;. When you write cout << MIN * MAX; the compiler makes a direct substitution of the defined values for MIN and MAX. The generated code will look like this :

Code:

---

cout<<7; * 8;;

---

That, of course, is not syntactically correct. :)

You might find this FAQ helpful.

It was a quick example so that's why I forgot return statement. :$

Thanks everyone! I didn't know they held stuff like that... Thanks Cilu for the article I read it top to bottom...