make a preprocessor

Hello everybody, i'm a computing student and i'm working in making a php compiler.

I have to make something like a preprocess to treat the #include sentences contained in the php scripts. I'm working with LEX/YACC and now i'm trying to make a function that can copy the code from a source file to another.

Doing this, if the source file is large, i obtain a "segment violation".

And I don't know how to append the read text instead of overwrite it...

Code:

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#include <stdio.h>

int main(int argc, char *argv[])
{
        FILE *fuente;
        FILE *destino;
    fuente = fopen(argv[1], "r");
        destino = fopen("prueba.php", "w");

        char *linea;
        int tam = 999;

    if (fuente == NULL) {
      printf("El fichero fuente no existe\n");
      return(-1);
      }
    else{
  while (!feof(fuente)){
          fgets(linea,tam,fuente);
          fputs(linea,destino);       
          printf("%s\n",linea);
  }
   
  fclose(fuente);
  fclose(destino);

    } 

}

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I'll be very pleased if someone could give me an idea or if anybody could tell me something about preprocessing that.

Thanks!!!

Quote:

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char *linea;
int tam = 999;
fgets(linea,tam,fuente);

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You are telling to fgets that the linea pointer points to the buffer able to store 999 bytes
But actually it contains some random adress.
so when fgets starts writing there or GPF occurs or some random memory of your process is overwritten

Quote:

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And I don't know how to append the read text instead of overwrite it...

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You should read about file open modes... i think "a" will suite you

> while (!feof(fuente))
And read the FAQ on why using feof() to control a loop is bad.

What's to say that argv[1] isn't NULL? You should check the number of command-line parameters passed to the program. And whether or not the files could be opened.

Also, declaring variables in the middle of a block is C99.

I'checked all your comments (thank you guys) and I think my problem actually is about the memory and what vart has written...

How can I resolve that? Do you know about a good guide or FAQ or something similar about files in C?

Thank you very much

Why read the file in the first place? You can tell LEX to use a different source temporarily. The documentation contains a section on that.

Quote:

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Originally Posted by CornedBee

Why read the file in the first place? You can tell LEX to use a different source temporarily. The documentation contains a section on that.

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I've read this documentation and it seems too dificult and I have no much time, but it's ok, I've found a solution with a simple memory allocation.

Thank you all, see ya