Thread: Problem with linking files

I'm having trouble with these files:

Code:

/* File peptide.c */
#include <stdio.h>
#include <stdlib.h>
#include "residues.c"

/* Simulate a peptide sequence and report its hydropathy index */

int main(void) {

  puts("Your peptide sequence is\n");
  puts(strcat(sequence(), " ."));

  puts("\n\n");

  printf("Cumulative hydropathy: %f;\n"
         "average hydropathy: %2.1f.\n", hp, hp/20.);
}

/* --------------- */

/* File residues.c */

#include "peptide.h"

char* sequence(void) {

  int aaLeft = 20;
  char* seq = "NH2-"; /* Build from the N-terminus of the chain. */

  seq = malloc(120 * sizeof(char));

  while(aaLeft--) {
    int aa;

    aa = random() % 20; /* Randomly choose an amino acid from the list */

    seq = strcat(seq, residue[aa]);
    hp += hpi[aa];
  }

  seq = strcat(seq, "COOH"); /* We're done */

  return seq;
}

/* --------------- */

/* File peptide.h */

#include <stdio.h>
#include <stdlib.h>

char* residue[20] = { "Ile-", "Val-", "Leu-", "Phe-", "Cys-", "Met-",
                       "Ala-", "Gly-", "Thr-", "Ser-", "Trp-", "Tyr-",
                       "Pro-", "Gln-", "Asn-", "Asp-", "Glu-", "His-",
                       "Lys-", "Arg-" };

float      hpi[20] = { 4.5, 4.2, 3.8, 2.8, 2.5, 1.9,
                       1.8, -0.4, -0.7, -0.8, -0.9, -1.3,
                       -1.6, -3.5, -3.5, -3.5, -3.5, -3.2,
                       -3.9, -4.5 };

extern float   hp; /* Running count of the hydropathy. */


/* That's all, folks... */

Here's what happens when I try to compile and link:

Code:

127.0.0.1> gcc -o peptide residues.c peptide.c

/tmp/cclu2H5r.o(.data+0x0): multiple definition of `residue'
/tmp/ccU47JJi.o(.data+0x0): first defined here
/tmp/cclu2H5r.o(.data+0x60): multiple definition of `hpi'
/tmp/ccU47JJi.o(.data+0x60): first defined here
/tmp/cclu2H5r.o(.text+0x0): In function `sequence':
: multiple definition of `sequence'
/tmp/ccU47JJi.o(.text+0x0): first defined here
/tmp/ccU47JJi.o(.text+0x65): In function `sequence':
: undefined reference to `hp'
/tmp/ccU47JJi.o(.text+0x72): In function `sequence':
: undefined reference to `hp'
/tmp/cclu2H5r.o(.text+0x65): In function `sequence':
: undefined reference to `hp'
/tmp/cclu2H5r.o(.text+0x72): In function `sequence':
: undefined reference to `hp'
/tmp/cclu2H5r.o(.text+0x100): In function `main':
: undefined reference to `hp'
/tmp/cclu2H5r.o(.text+0x115): more undefined references to `hp' follow
collect2: ld returned 1 exit status

Thanks.

you might new some more header files including in your header file such as string.h and perhaps Salem said you need a ifndef enclosing the header content so that they don't get initialized every time.

ssharish