Re: Portability / compatibility issues

OzBob wrote:
"Michael Mair" <Michael.Mair@xxxxxxxxxxxxxxx> wrote in message news:42v1nlF1l3ge0U1@xxxxxxxxxxxxxxxxx

OzBob wrote:

I am developing some basic string / file manipulation C progams at home (Sparcstation running Solaris 9 and gcc) for my work environment (PA-RISC running HP-UX 11.11 and c99 compatible compiler). However I seem to have encountered problems performing the most basic of manipulations and comparisons.

I have posted my test code below, and the results I get on each compiler. The crux of the matter is that the 'strstr' function differs wildly in its behaviour on different platforms, and precious few man pages will actually provide a worked example of any function, let alone this one. I have had to write the "has_slash" function and use the reserved work SLASH already, to get around the problems that strstr() gives me.

I know C is touted as an standardised development environment that provides portability (the immortal phrase "we converted to another platform by typing 'make'" springs to mind); I'm not seeing that right now.

Any advise / comments? Share and Enjoy, Ian 


Yes: Compile with the highest warning level and in a standard C
mode. E.g.

$ gcc -std=c99 -pedantic -W -Wall -O strstr.c -c
strstr.c: In function `has_slash':
strstr.c:9: warning: comparison between pointer and integer
strstr.c: At top level:
strstr.c:24: warning: return type of 'main' is not `int'
strstr.c: In function `main':
strstr.c:35: warning: implicit declaration of function `strcpy'
strstr.c:36: warning: implicit declaration of function `strstr'
strstr.c:36: error: missing terminating " character
strstr.c:37: error: stray '\' in program
strstr.c:37: error: `slash' undeclared (first use in this function)
strstr.c:37: error: (Each undeclared identifier is reported only once
strstr.c:37: error: for each function it appears in.)
strstr.c:37: error: parse error before "n"
strstr.c:36: warning: empty body in an if-statement
strstr.c:37: error: missing terminating " character
strstr.c:38: error: `n' undeclared (first use in this function)
strstr.c:38: error: missing terminating " character
strstr.c:39: error: missing terminating " character

where the include directive is on line 1.

Your program does not compile -- so how can you expect us to
look at it?

<snip>
Micheal, 

I'm not that Irish ;-)

Have submitted the commands for gcc, with the following response. Have also checked the code and string.h is not included. I have since modified the comments at the end, included the <string.h> library at the start, and succesfully compiled using the commands provided. I even went a step further and removed the "-c" option from the command string to generate "a.out", which (in the interests of consistency) fails at the same point with the same error.

I figure its the strstr command and the assignment of a pointer, which again, works fine on the HP-UX 'cc' compiler (the full one, not the inbuilt kernel-only one) with the '-AC99' c99 compatibility option, yet bails on the gcc compiler.

Any further ideas? Share and Enjoy, OzBob

/* original compiler output */
# gcc -std=c99 -pedantic -W -Wall -O test.c -c
test.c:24: warning: return type of `main' is not `int'
test.c: In function `main':
test.c:35: warning: implicit declaration of function `strcpy'
test.c:36: warning: implicit declaration of function `strstr'
test.c:53:1: unterminated comment

/* included <string.h>, terminated comment */
# gcc -std=c99 -pedantic -W -Wall -O test.c
test.c:25: warning: return type of `main' is not `int'


Note: This is not to be taken lightly -- in principle, all
bets are off for a "void main" main().

ls # -l a.out
-rwxr-xr-x   1 root     other       7280 Jan 15 15:04 a.out
# ./a.out
In function - i = 6
Has slash = true
 By self- not found slash
Segmentation Fault - core dumped
#

<snip>

Look at this one; it is yours with slight changes and works
as I expect:

#include <stdio.h>
#include <string.h>

#define SLASH "/"

int has_slash (const char *in_str);

int main (void)
{
  int     test_true;

  test_true = has_slash("copy /f file");
  if (test_true != 0)
    printf("Has slash = true\n");

  /* New test, strstr results */
  char    *str_result;
  char    test_date[24];

  strcpy(test_date, "02_04_2005");
  if (strstr(test_date, SLASH) != NULL)
    printf(" By self- found slash\n");
  else
    printf(" By self- not found slash\n");

  str_result=strstr(test_date, "/");

  if (str_result != NULL)
    printf("Found slash:     %s[%s]\n",
           str_result, test_date);
  if (str_result == NULL)
    printf("Not found slash: \'\\0\'[%s]\n",
           test_date);

  return 0;
}

int has_slash (const char *in_str)
{
  int     i=0;

  while (in_str[i] != *SLASH && in_str[i] != '\0'
         /* && i < 100 */)
    i++;

  /* wrong format */
  i = (in_str[i] != *SLASH) ? 0 : i+1;

  printf("In function - i = %i\n", i);

  return(i);
}

Cheers
 Michael
--
E-Mail: Mine is an   /at/ gmx /dot/ de   address.
.

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