Problem using getline functions

[kraj]

I am using PellesC 7.00.355.
I have included stdio.h, as required by the getline function.
I am running some sample code, as follows:

Code: [Select]

  char * line = NULL;
  size_t len = 0;
  ssize_t read;
  while ((read = getline(&line, &len, stdin)) != -1) {
    printf("Retrieved line of length %zu :\n", read);
    printf("%s", line);
  }
  if (line)
    free(line);
When building, I am getting the following errors:

Building main.obj.
D:\Program Files\PellesC\Projects\TrapHandle\traphandle\main.c(40): error #2048: Undeclared identifier 'ssize_t'.
D:\Program Files\PellesC\Projects\TrapHandle\traphandle\main.c(40): error #2001: Syntax error: expected ';' but found 'read'.
D:\Program Files\PellesC\Projects\TrapHandle\traphandle\main.c(40): error #2048: Undeclared identifier 'read'.
D:\Program Files\PellesC\Projects\TrapHandle\traphandle\main.c(43): warning #2018: Undeclared function 'getline'; assuming 'extern' returning 'int'.
*** Error code: 1 ***
Done.

After looking at stdio.h, I cahnged the definition from ssize_t to _ssize_t, at which time it compiled, but gave me a warning:

Building main.obj.
D:\Program Files\PellesC\Projects\TrapHandle\traphandle\main.c(43): warning #2018: Undeclared function 'getline'; assuming 'extern' returning 'int'.
Building traphandle.exe.
Done.

[Bitbeisser]

Well, not sure to tell by just the snippet you posted (as that is not a compilable program!)

Otherwise, what's up with that ssize_t stuff?
The type in stdio.h is defined as size_t, just as you are using it to declare len.

And free() is declared in stdlib.h, not in stdioh.h

Beside that, I still get that strange error about getline() not defined, will have to see about that one after I had something for dinner...

Ralf

[TimoVJL]

Code: [Select]

#define __STDC_WANT_LIB_EXT2__ 1
#include <stdio.h>
...

[CommonTater]

Here's a working example using getline to fetch characters from the keyboard...

Code: [Select]

// example using getline
#define __STDC_WANT_LIB_EXT2__ 1
#include <stdio.h>
#include <stdlib.h>

int main (void)
  {
    ssize_t chars;
    char* line = calloc(10,sizeof(char));
    size_t size = 10;
 
    chars = getline(&line, &size, stdin);
 
    printf("You typed :\n%s\n",line);
    printf("%d chars, buffer is %d chars\n\n",chars, size);
 
    free(line);

    return 0;
  }
(Note that line cannot be NULL and the carriage return (\n) is stored in the string before the null terminator)

[TimoVJL]

(Note that line cannot be NULL and ...)

It can

Setting *lineptr to a null pointer and *n to zero are allowed and a recommended way to start parsing a file.

http://pubs.opengroup.org/onlinepubs/9699919799/functions/getline.html

[CommonTater]

(Note that line cannot be NULL and ...)

It can

Setting *lineptr to a null pointer and *n to zero are allowed and a recommended way to start parsing a file.

http://pubs.opengroup.org/onlinepubs/9699919799/functions/getline.html

I got exceptions when I tried it Timo... Maybe a Pelles C specific thing?

The Pelles C help file doesn't say anything about it.

[Bitbeisser]

I get the sample to compile bar that strange getline() error during compile... 

I also found out that the sample that the OP posted is from a GCC (*ix) specific example that can be found on SourceForge.

Just haven't gotten a clue as to why the getline() call doesn't compile as used, the declaritions in the include file is there but surrounded by a plethora of #if...

Might try to simplify the expression to narrow this down, but I am all day so far busy chasing after clients who owe me money... 

Ralf

[CommonTater]

I get the sample to compile bar that strange getline() error during compile... 

I also found out that the sample that the OP posted is from a GCC (*ix) specific example that can be found on SourceForge.

Just haven't gotten a clue as to why the getline() call doesn't compile as used, the declaritions in the include file is there but surrounded by a plethora of #if...

Might try to simplify the expression to narrow this down, but I am all day so far busy chasing after clients who owe me money... 

Ralf

Hi Ralf... 
I tested it this morning, with my coffee... the example I posted does work.  You have to enable the extensions to make it work, hense the first #define in my sample.  (Thanks for that to Timo, by the way)

What seems puzzling is that most texts recommend starting with the line buffer at NULL... but I got a memory access exception when I did that.  I'm going to guess that's an implementation specific thing.  Pelles help file says it will expand the buffer... It doesn't say it will make the first allocation.

And yes pulling GCC examples off unix boards is probably not the best way to learn Windows C.

[Stefan Pendl]

How about initializing to zero?

Code: [Select]

char * line = {0};

[TimoVJL]

Modified CT's example that works with 32/64-bit:

Code: [Select]

// example using getline
#define __STDC_WANT_LIB_EXT2__ 1
#include <stdio.h>
#include <stdlib.h>

int main(void)
{
int chars;
//char *line = calloc(10, sizeof(char));
//unsigned int size = 10;
char *line = NULL;
size_t size = 0;

chars = getline(&line, &size, stdin);

printf("You typed :\n%s\n", line);
printf("%d chars, buffer is %d chars\n\n", chars, size);

free(line);

return 0;
}TR 24731-2:
http://www.open-std.org/jtc1/sc22/wg14/www/projects
http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1337.pdf

[CommonTater]

Modified CT's example that works with 32/64-bit:

HMMMM.... Now I have to wonder what the heck was going on this morning?

Perhaps I should wait till after my morning coffed to write code samples...