What does the “undefined reference to varName” in C mean?

Question

I have 2 files: a.c and b.c

In a.c I am sending a signal to a function located in b.c

signal(SIGU         


        

Answer 1

It is very bad style to define external interfaces in .c files. .

You should do this

a.h

    extern void doSomething (int    sig);

a.c

    void doSomething (int    sig)
    {
       ... do stuff 
    }

b.c

#include "a.h"
.....
signal(SIGNAL, doSomething); 

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