Missing Prototype

[kreagan]

I am out of ideas for this problem.

I have a .c file name AAT which includes TestUtilities.h. Within TestUtilities, I have a method named measureResistance() that AAT calls throught the code. TestUtilities also has other functions which AAT calls too. However, I get the error "Missing Prototype" for only measureResistance() calls.

Yes, I checked the the spelling in the AAT.c, TestUtilities.h, and TestUtilities.c files. The spelling and parameters are correct throught the three files.

Yes, I did include the .h file in the project.

Again, there are no other functions which generate this error within TestUtilities.

~Kat

[weaknessforcats]

Locate the function definition for measureResistance and copy the first line to the prototype in TestUtilities.h. Add a semi-colon and rebuild. Often this error occurs not becuse the function name was incorrect but that the arguments or return type didn't match.

If that doesn't do it, post that section of TestUtilities.h and AAT.c where a call is made and I'll look at it.

[kreagan]

Thanks for the help and quick response.

FYI, This is C, not C++. If I had different number of arguements, the compiler would state: "Insufficient number of arguement ...." or if the arguements were of the wrong type, the error would say, "Expecting TYPE A found TYPE B". From my understanding, method overloading doesn't exist in C.

AAT.C
#include "TestUtilities.h"
...
// Measure Resistance. Result should be 1700 ohms +/- 10%
status = measureResistance();
if ( status == 0 ){ status = testResistance( test_resistance, percent_error); }
....

TestUtilities.C
int measureResistance(){
status = 0;

status = APP_DMM_Measure("resistance", &resistance );

if (status !=0){ EL_logErrorData(status, "Error Measuring Resistance"); }

return status;
}

TestUtilities.h
....
int measureResistance();
int testResistance( int test_resistance, double percent_error);
....

[weaknessforcats]

This compiles as C using Visual Studio.NET 2005.

I only had to change measueResistance() to explicity create the status variable.

int measureResistance(){
int status = 0;    <<<<------- explicit int
 
//status = APP_DMM_Measure("resistance", &resistance ); 
 
//if (status !=0){ EL_logErrorData(status, "Error Measuring Resistance"); } 
 
return status; 
}
//////////////////
int main()
{
    // Measure Resistance. Result should be 1700 ohms +/- 10%
int status;
status = measureResistance();
//if ( status == 0 ){ status = testResistance( test_resistance, percent_error); }
//.... 
 
}
 

[kreagan]

This compiles as C using Visual Studio.NET 2005.

I only had to change measueResistance() to explicity create the status variable.

status is a global variable declaired elsewhere in the file.

Are you saying there is something wrong with my IDE/compiler? I'm using Lab Windows.

Furthermore, I can't place the function within the AAT.c for maintance reason. (The file is 3000+ lines of code and needs to be made into seperate files (classes?) soon).

I been coding in Java for the past 4 years and relatively new to C. Could there be a problem with how I'm accessing the TestUtilities class/functions? And what bothers me more is that I can access every other function in TestUtilities except measureResistance().

[kreagan]

Yay! I found the problem.

TestUtilities.h

....
int measureResistance();
int testResistance( int test_resistance, double percent_error);
....

instead of int measureResistance();
it should have been

int measureResistance(void);

[weaknessforcats]

Ah, I missed that. I do C++ so much that empty parentheses mean no arguments but in C mean a function.

C has that feature where the arguments can be specified on the first call. That's a big problem area sonce there's no guarantee of consistency from one .c file to the next.