Thread: When to use header files?

The #include "plot.h" in file1.c does'nt seem to make a difference.
If I remove the line with #include plot.h it still compiles.

I have a structure as below:

├── build
├── include

└── plot.h

└── src

├── file1.c

└── plot.c

file1.c

Code:

  #include <stdio.h>
  #include <stdlib.h>
  #include "plot.h"
  
  int main(void) {
  
      plotXY(3,4);
  
      return 0;
  }

plot.c

Code:

  #include <stdio.h>
  #include <stdlib.h>
  
  void plotXY(int x,int y) {
  
      printf("Res: %d\n",x*y);
  }

plot.h

Code:

void plotXY(int x,int y);

I'm using the following to compile the code:

gcc src/plot.c -o build/plot.o -c
gcc src/file1.c -o build/file1.o -c -I ./include
gcc -o pgm1 build/file1.o build/plot.o

I would like to add that I suggest that you always compile with at least the flags "-W" and "-Wall", then you would see that your compiler probably issued a warning.

OK, I see.

Regarding the "-W"and "-Wall" flags you are correct. I got a warning telling me "impilicit declaration ..."

Thanks for the clarification.