Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.c > #140149

Re: Function to trim trailing spaces

Show key headers only | View raw

mark.bluemel@gmail.com writes:
[...]
> As already mentioned, there are enough obvious ones to
> be going on with.
>
> If ever there was an example of the need for Test
> Driven Development, this looks like it - not because 
> the task is hard, but because programmers need to be
> made to think.
>
> Please tell us what happens when you run the following
> snippets.
>
>   char *s = "my dog has fleas";
>   printf("Before: '%s'\n",str);
>   rtrim(str);
>   printf("After : '%s'\n",str);

It can fail because string literals are read-only.  But who says rtrim()
need to work with read-only data?  There needs to be some documentation
indicating whether it modifies the input or returns a pointer to a new
string.  (The fact that the parameter is defined as char* and not const
char* is IMHO enough to document that fact.  The fact that string
literals are not const is an unfortunate historical artifact.)

[...]

> Here's my 10-minute simplistic hack to do the job.
> The rtrim() function is not elegant, but suffices, and my main
> point is to show some basic ideas about how you could use testing.
> (My more complete example would test the results against expected
> values).
>
> #include <string.h>
> #include <stdio.h>
> #include <stdlib.h>
>
> char *rtrim(char *str) {
>   char * result = strdup(str);

strdup() is defined by POSIX but not by ISO C.  (It's easy enough to
write your own.)

>   int i = strlen(result);

You didn't check whether the allocation failed.

>   for (i = i-1; i >= 0 && result[i]==' '; i--) {
>     result[i] = 0;
>   }
>   return result;
> }
>
> int main(void) {
>
>   char * testStrings[] = {
>     "my dog has no spaces",
>     "my dog has one space ",
>     "my dog has lots of spaces               ",
>     " ",
>     "    "
>   };
>
>   int i;
>
>   for (i = 0; i < sizeof(testStrings)/sizeof(testStrings[0]); i++) {
>     char *trimmed = rtrim(testStrings[i]);
>     printf("before '%s' after '%s'\n", testStrings[i], trimmed);
>     free(trimmed);

This version requires the caller to free the allocated memory, a
drawback that the original function doesn't have.

>   }
>
> }

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Will write code for food.
void Void(void) { Void(); } /* The recursive call of the void */

Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Function to trim trailing spaces DFS <nospam@dfs.com> - 2019-01-23 21:00 -0500
  Re: Function to trim trailing spaces Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-01-23 19:14 -0700
    Re: Function to trim trailing spaces DFS <nospam@dfs.com> - 2019-01-23 23:41 -0500
      Re: Function to trim trailing spaces Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-01-23 22:40 -0700
        Re: Function to trim trailing spaces Bart <bc@freeuk.com> - 2019-01-24 10:44 +0000
        Re: Function to trim trailing spaces DFS <nospam@dfs.com> - 2019-01-24 11:20 -0500
          Re: Function to trim trailing spaces Bart <bc@freeuk.com> - 2019-01-24 16:47 +0000
            Re: Function to trim trailing spaces DFS <nospam@dfs.com> - 2019-01-24 13:51 -0500
          Re: Function to trim trailing spaces Manfred <noname@invalid.add> - 2019-01-24 17:49 +0100
        Re: Function to trim trailing spaces James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-01-24 08:52 -0800
          Re: Function to trim trailing spaces Bart <bc@freeuk.com> - 2019-01-24 17:40 +0000
          Re: Function to trim trailing spaces James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-01-24 12:08 -0800
            Re: Function to trim trailing spaces Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-01-24 14:47 -0700
              Re: Function to trim trailing spaces scott@slp53.sl.home (Scott Lurndal) - 2019-01-25 14:40 +0000
          Re: Function to trim trailing spaces Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-01-24 14:44 -0700
      Re: Function to trim trailing spaces Barry Schwarz <schwarzb@dqel.com> - 2019-01-23 23:39 -0800
        Re: Function to trim trailing spaces Rosario19 <Ros@invalid.invalid> - 2019-01-24 10:49 +0100
          Re: Function to trim trailing spaces mark.bluemel@gmail.com - 2019-01-24 01:55 -0800
    Re: Function to trim trailing spaces "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-24 12:58 +0100
    Re: Function to trim trailing spaces Nathan Wagner <nw@hydaspes.if.org> - 2019-01-24 03:01 +0000
  Re: Function to trim trailing spaces Keith Thompson <kst-u@mib.org> - 2019-01-23 18:46 -0800
    Re: Function to trim trailing spaces DFS <nospam@dfs.com> - 2019-01-23 23:38 -0500
      Re: Function to trim trailing spaces Barry Schwarz <schwarzb@dqel.com> - 2019-01-23 23:39 -0800
        Re: Function to trim trailing spaces DFS <nospam@dfs.com> - 2019-01-24 11:25 -0500
          Re: Function to trim trailing spaces mark.bluemel@gmail.com - 2019-01-24 08:34 -0800
          Re: Function to trim trailing spaces Barry Schwarz <schwarzb@dqel.com> - 2019-01-24 15:05 -0800
            Re: Function to trim trailing spaces DFS <nospam@dfs.com> - 2019-01-24 18:40 -0500
      Re: Function to trim trailing spaces Keith Thompson <kst-u@mib.org> - 2019-01-24 02:29 -0800
        Re: Function to trim trailing spaces DFS <nospam@dfs.com> - 2019-01-24 15:06 -0500
          Re: Function to trim trailing spaces Mateusz Viste <mateusz@wont.tell> - 2019-01-24 20:07 +0000
            Re: Function to trim trailing spaces scott@slp53.sl.home (Scott Lurndal) - 2019-01-24 20:24 +0000
              Re: Function to trim trailing spaces Mateusz Viste <mateusz@wont.tell> - 2019-01-24 20:34 +0000
                Re: Function to trim trailing spaces scott@slp53.sl.home (Scott Lurndal) - 2019-01-24 21:37 +0000
          Re: Function to trim trailing spaces Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2019-01-24 15:34 -0500
          Re: Function to trim trailing spaces James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-01-24 13:19 -0800
          Re: Function to trim trailing spaces Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-01-24 14:52 -0700
            Re: Function to trim trailing spaces James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-01-24 14:30 -0800
              Re: Function to trim trailing spaces Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-01-24 16:59 -0700
          Re: Function to trim trailing spaces Keith Thompson <kst-u@mib.org> - 2019-01-24 14:51 -0800
  Re: Function to trim trailing spaces mark.bluemel@gmail.com - 2019-01-24 01:06 -0800
    Re: Function to trim trailing spaces Keith Thompson <kst-u@mib.org> - 2019-01-24 02:13 -0800
      Re: Function to trim trailing spaces mark.bluemel@gmail.com - 2019-01-24 03:46 -0800
    Re: Function to trim trailing spaces Anton Shepelev <anton.txt@g{oogle}mail.com> - 2019-01-24 14:56 +0300
      Re: Function to trim trailing spaces mark.bluemel@gmail.com - 2019-01-24 05:14 -0800
      Re: Function to trim trailing spaces Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-01-24 18:51 +0000
        Re: Function to trim trailing spaces "Pascal J. Bourguignon" <pjb@informatimago.com> - 2019-01-24 20:04 +0100
          Re: Function to trim trailing spaces Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-01-24 20:25 +0000
          Re: Function to trim trailing spaces Anton Shepelev <anton.txt@gmail.com> - 2019-01-24 23:50 +0300
        Re: Function to trim trailing spaces Anton Shepelev <anton.txt@gmail.com> - 2019-01-24 23:45 +0300
          Re: Function to trim trailing spaces Anton Shepelev <anton.txt@gmail.com> - 2019-01-24 23:54 +0300
      Re: Function to trim trailing spaces Ralf Damaschke <rwspam@gmx.de> - 2019-01-24 22:43 +0000
  Re: Function to trim trailing spaces Bart <bc@freeuk.com> - 2019-01-24 10:57 +0000
    Re: Function to trim trailing spaces Bart <bc@freeuk.com> - 2019-01-24 23:05 +0000
  Function to trim trailing spaces "I Set My Girlfriend's Pantyhose on Fire" <cdalten@gmail.com> - 2019-01-24 03:53 -0800

csiph-web