Compiler Help Needed

[deltacoder1020]

notice that the error you are getting is a link error - this means that the multiple definitions are in different files - are you sure you didn't accidentally name something (even a variable) newValue somewhere else?

[Mark McLeod]

Originally Posted by Darkman_X000

Ok, thanks for the info guys, but my problem still isn't fixed. I still get the error about having multiple definitions, even though I don't. I have included the preprocessor directives #ifndef, #define, #endif to prevent such nonsense from bothering me, but to no avail. I have written several functions that I NEED to make my robot work right, and it is extremely frustrating to have the compiler return errors that are unfounded.

Please help!

My code is presented on the previous page, and I don't want to re-post it because it is long... Please check it out and tell me why the function "newValue" keeps coming up as having "multiple definitions"!



Thanx in advance!!!!!!

The code you posted here compiles without a problem.
You need to post or email one of us your whole project as a zip file.
Strip out the project and .o files before you Winzip it if you need to keep the size down.

[Astronouth7303]

I don't know. It looks like the only defs are the prototype and the actual code. I would say try putting the prototype in the same file as the sub.

[Greg Ross]

Originally Posted by Mark McLeod

The code you posted here compiles without a problem.
You need to post or email one of us your whole project as a zip file.
Strip out the project and .o files before you Winzip it if you need to keep the size down.

I second the motion. There must be something going behind the scenes of what you've shown us.

[Darkman_X000]

All right guys, it seems to be working now. I just deleted all #include "userutilities.c" directives and replaced them with #include "userutilities.h" directive where necessary.

So... now I am no longer getting the "multiple definition" errors that were driving me insane. Thanks for your help!!!

[Mike Soukup]

Originally Posted by Darkman_X000

Note: these are the only files that contain the definitions of these functions and varibles. There are NO duplicate names or any of that.
WHAT IS GOING ON!?!?!?!?!?!?!?!?!?
Clearly, including the file multiple times is prevented by the preprocessor #ifndef, #define, #endif statements, but it is acting like it just disregards those...

The problem is actually with the line "extern float axleWidth". Since you're including the header that has the declaration of "axleWidth" there is no need to re-declare it inside your function. 'extern' is only used when you have a global variable defined in another file.

From the names of your variables & the way you use them, it looks like those are values that will never change while your code is being executed, ie a constant. If so, there is no need to use a variable to store the values, use a #define instead:

#define axelWidth  .725
#define wheelRadius  .105
#define clicksPerRevolution  16

Post more questions if you have them.

[Darkman_X000]

Ok, I just replaced what I had before with:

#define axelWidth  .725
#define wheelRadius  .105
#define clicksPerRevolution  16

and I have deleted the externs. Now the compiler has no trouble with "axelWidth". Instead it says:

MPLINK 3.40, Linker
Copyright (c) 2003 Microchip Technology Inc.
Error - symbol 'newValue' has multiple definitions.
Errors    : 1

BUILD FAILED: Sat Feb 07 12:05:03 2004

I wrote the function prototype in UserUtilities.h and the actual function definition in UserUtilities.c. There should be no conflicts here because prototypes ARE allowed.

Each time I fix a problem with one function or variable name in the set of files, it has a problem with the next one down the line.

Please consider that because bool.h has the necessary preprocessor statements, including it multiple times should not be a problem... right? Isn't that the primary use of #ifndef, #define, and #endif structures in header files?

I also tried to delete the #include "userutilities.h" line from UserUtilities.c after making the above changes, but then it said that axelWidth and wheelRadius were not defined. Can I use extern with a variable that was #defined?

Here is the updated version of my files:

UserUtilities.h
#ifndef USERUTILITIES_H
#define USERUTILITIES_H

#include "bool.h"

#define axelWidth .725
#define wheelRadius .105
#define clicksPerRevolution 16

/*float axelWidth = .725;
float wheelRadius = .105;
int clicksPerRevolution = 16;*/

bool newValue(int *staticVar, int dynamicVar);
float thetaDegrees(int c);
float thetaRadians(int c);
float Forward(int c);
void move(float distance);
void turnLeft(float degrees);
void turnRight(float degrees);

#endif

UserUtilities.c
#ifndef USERUTILITIES_C
#define USERUTILITIES_C

#include "bool.h"
#include "UserUtilities.h"

bool newValue(int *staticVar, int dynamicVar)
{
	
	if (*staticVar==dynamicVar)
	{
		*staticVar=dynamicVar;
		return true;
	}
	else
	{	
		return false;
	}
}

float thetaDegrees(int clicks)
{
	clicks*=22.5;
	clicks=clicks*wheelRadius;
	clicks/=(float)axelWidth;
	return clicks; //22.5*(float)wheelRadius*clicks/(float)axelWidth;
}

float thetaRadians(int clicks)
{
	clicks*=3.1415926;
	clicks=clicks*wheelRadius;
	clicks/=8*axelWidth;
	return clicks;
}

#endif

[Astronouth7303]

Originally Posted by Mike Soukup

... From the names of your variables & the way you use them, it looks like those are values that will never change while your code is being executed, ie a constant. If so, there is no need to use a variable to store the values, use a #define instead:

#define axelWidth  .725
#define wheelRadius  .105
#define clicksPerRevolution  16

...

I, personally, have had problems with #declare in place of const, and only use it for alias, Example:

//Some constants
const char Varience = 10;
const char True = 255;
const char bLAH = 152;

//Some aliases
#declare Left_OI p1_y
#declare Left_Motor pwm01
#declare DyNoMiTe relay8

As long as you keep it in headers and include them, you should be ok.

[deltacoder1020]

first of all, it's "#define", not "#declare"

second, the reason you are having problems is because mcc18 automatically casts any number from 0 to 255 as an unsigned char, which can screw up math. instead, what you'd want is this:

#define Varience ((char) 10)