problems with source/header files

[pabloist]

Okay, so I have a source file, rangedRandom.cpp, that holds two functions for getting random numbers within supplied ranges.

I have two other source files that use the rangedRandom functions. I try to compile, but one of them complains that rangedRandom functions haven't been defined. Do I need to make rangedRandom a .h file and then #include it in both files? I tried that and got multiple declaration errors, even though I used header guards..

(Please know that this is the first time I'm trying to work with header/source files, and am very confused right now)

[firedraco]

See: http://www.cplusplus.com/forum/articles/10627/

It seems you have it basically correct, but I'd have to see the code to be sure.

[pabloist]

From what I'm reading, it looks like whenever you make a header/source file, all functions inside should be part of some class. That might be my problem then - I had written the rangedRandom functions without any class.. is there a way for me to avoid writing a class for it? As in, simply writing:


randRange.cpp

int    random::randomInRange(int a, int b)             // random int between [a,b]
{
    randInt = rand()%(b-a)+a;
}

main.cpp

cout << randomInRange(0,20);

[LB]

Functions don't need to be in a class. Just put them in the header file and it should be fine ;)

[pabloist]

:( Okay, I tried putting it in a header file:

#ifndef RANGEDRANDOM_H_INCLUDED
#define RANGEDRANDOM_H_INCLUDED

using namespace std;

// HELPER FUNCTIONS -----------------------------
int    randomInRange(int a, int b)             // random int between [a,b]
{
    return rand()%(b-a)+a;
}

double randomInRange(double a, double b)    // random double between [a,b]
{
    double randNum = static_cast<double>(rand())/static_cast<double>(RAND_MAX);
    return randNum*(b-a)+a;
}
// ----------------------------------------------

#endif // RANGEDRANDOM_H_INCLUDED 

I'm still getting multiple definition errors :/ Shouldn't the include guard be taking care of this?

[Disch]

You put the prototypes in the header.

You put the implementation (function body) in the cpp file.

The function body can only go in the header if the function is a template or is inlined.

Your header:

#ifndef RANGEDRANDOM_H_INCLUDED
#define RANGEDRANDOM_H_INCLUDED

// HELPER FUNCTIONS -----------------------------
int    randomInRange(int a, int b);             // random int between [a,b]
double randomInRange(double a, double b);    // random double between [a,b]
// ----------------------------------------------

#endif // RANGEDRANDOM_H_INCLUDED  

Your cpp file:

#include <cstdlib>
#include "rangedrandom.h"

using namespace std;

int    randomInRange(int a, int b)
{
    return rand()%(b-a)+a;
}

double randomInRange(double a, double b)
{
    double randNum = static_cast<double>(rand())/static_cast<double>(RAND_MAX);
    return randNum*(b-a)+a;
}

[pabloist]

Oh! I should have done more than skimmed that article. Changing the #include "rangedrandom.h" into foward declarations of it worked. Thanks for all the help, this was a nightmare.

Edit:

Oh, alright! Thank you, disch.