Newbiest of Newbie Questions:

Ok, folks. I'm decent with C++, but there's some C things that confuse and anger me. So, just incase I ever need them, how do #define and printf work? I haven't had a use for either, yet. I'm pretty sure #define is important if you wanna make your own function libraries and such. Little help?

hmm...i really don't know C, but the most common ways I have seen #define are with classes (C++ obviously), and similar to how constants work.

i.e
#define MAX = 20;
instead of
const int = 20;

I could be wrong though.

printf I have seen to be similar to cout...

Code:

---

#include <stdio.h>

#define THE_WORLD_IS_ROUND (1)

int main()
{
        if THE_WORLD_IS_ROUND
                printf("Hello World!\n");

        return 0;
}

---

Quote:

---

Originally posted by abrege

Code:

---

#include <stdio.h>

#define THE_WORLD_IS_ROUND (1)

int main()
{
        if THE_WORLD_IS_ROUND
                printf("Hello World!\n");

        return 0;
}

---

---

Eh? I'm a #define Newbie. You'll have to explain that.

It's basically search and replace
Replace all occourances of THE_WORLD_IS_ROUND with (1)

The only time I ever use defines in C++ are for class header files... like

#ifndef _KRAKS_CLASS_HPP_
#define _KRAKS_CLASS_HPP_

class Krak {};

#endif

Quote:

---

Originally posted by Eibro
It's basically search and replace
Replace all occourances of THE_WORLD_IS_ROUND with (1)

The only time I ever use defines in C++ are for class header files... like

#ifndef _KRAKS_CLASS_HPP_
#define _KRAKS_CLASS_HPP_

class Krak {};

#endif

---

Oy, I still dont exactly get it. ifndef?

Can someone define #define?

are you being a troll?


#define CODEPLACEMENT cout << "this is defined stuff" << endl;

int main (void)
{
CODEPLACEMENT
return 0;
}

all it does is replace the tag with the code

go read a book instead!

So.....

Code:

---

#define KRAK printf ("\nHello!");

int main(void)
{
KRAK;
return 0;
}

---

Would print "Hello!" to the screen?

whats wrong with compiling it yourself?

Quote:

---

Originally posted by Krak
So.....

Code:

---

#define KRAK printf ("\nHello!");

int main(void)
{
KRAK;
return 0;
}

---

Would print "Hello!" to the screen?

---

Remove the ';' behind KRAK because it's already in your define.

Code:

---

int x = 2;
printf("Hello %d \n Hello %d \n", 1, x )    // %d gets replaced with variables

---

This would display
Hello 1
Hello 2

There's a shipload of formatting characters that you can use in place of %d. for example %s is for a string.

sprintf() is similar. It builds a C-style string which can be stored, rather than being displayed.

[edit]
There was a post recently about #define being evil!! (Because it is global.)

So, this is preferred:
const int MAX = 20;