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Re: K&R2, exercise 5-4, strend(s,t)

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Mark Bluemel <mark_bluemel@pobox.com> writes:

> On 06/23/2011 11:56 AM, arnuld wrote:
>> K&r2, exercise 5-4, page 107
>>
>> Write the functions strend(s,t), which returns 1 if the string t occurs
>> at the end of the string s, and zero otherwise.
>
> Your solution presupposes strlen(), so it may as well presuppose
> strcmp(). If you don't already have them, write them as building
> blocks for this...
> [snip]
>
> /* return 1 if str2 occurs at the end of str1, zero otherwise */
>  int strend(const char* str1, const char* str2)
>   {
>     int str1_len;
>     int str2_len;
>     const char *comparison_start;
>
>     if ((str1 == NULL) || (str2 == NULL)) {
>       return 0;
>     }
>
>     str1_len = strlen(str1);
>     str2_len = strlen(str2);
>
>     if (str2_len  == 0) {
>       return 0;
>     }
>
>     if (str2_len > str1_len) {
>       return 0;
>     }
>
>     comparison_start = str1 + str1_len - str2_len;
>     return !strcmp(comparison_start,str2);
>   }


An alternative offered for everyone's reading pleasure
and/or amusement (as each may individually determine).


 /* Return 1 if 'tail' occurs at the end of 'whole', or 0 if not. */

 int
 strend( const char *whole, const char *tail ){
    size_t w, t;

    return
       whole  &&  tail
       &&   (w = strlen( whole ))  >=  (t = strlen( tail ))
       &&   strcmp( whole+w -t, tail ) == 0
    ;
 }

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K&R2, exercise 5-4, strend(s,t) arnuld <sunrise@invalid.address> - 2011-06-23 10:56 +0000
  Re: K&R2, exercise 5-4, strend(s,t) Ian Collins <ian-news@hotmail.com> - 2011-06-23 23:03 +1200
  Re: K&R2, exercise 5-4, strend(s,t) Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-06-23 13:28 +0100
  Re: K&R2, exercise 5-4, strend(s,t) Mark Bluemel <mark_bluemel@pobox.com> - 2011-06-23 14:08 +0100
    Re: K&R2, exercise 5-4, strend(s,t) Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-06-24 02:22 +0300
      Re: K&R2, exercise 5-4, strend(s,t) Gene <gene.ressler@gmail.com> - 2011-06-23 18:14 -0700
        Re: K&R2, exercise 5-4, strend(s,t) Ike Naar <ike@sverige.freeshell.org> - 2011-06-24 06:18 +0000
          Re: K&R2, exercise 5-4, strend(s,t) Ike Naar <ike@sverige.freeshell.org> - 2011-06-24 06:58 +0000
    Re: K&R2, exercise 5-4, strend(s,t) Tim Rentsch <txr@alumni.caltech.edu> - 2011-06-25 10:07 -0700
      Re: K&R2, exercise 5-4, strend(s,t) arnuld <sunrise@invalid.address> - 2011-06-27 08:02 +0000
        Re: K&R2, exercise 5-4, strend(s,t) Mark Bluemel <mark_bluemel@pobox.com> - 2011-06-27 10:13 +0100
        Re: K&R2, exercise 5-4, strend(s,t) Tim Rentsch <txr@alumni.caltech.edu> - 2011-06-27 11:54 -0700
      Re: K&R2, exercise 5-4, strend(s,t) Mark Bluemel <mark_bluemel@pobox.com> - 2011-06-27 09:07 +0100
        Re: K&R2, exercise 5-4, strend(s,t) Tim Rentsch <txr@alumni.caltech.edu> - 2011-06-27 11:51 -0700
          Re: K&R2, exercise 5-4, strend(s,t) Mark Bluemel <mark_bluemel@pobox.com> - 2011-06-28 08:19 +0100
            Re: K&R2, exercise 5-4, strend(s,t) Tim Rentsch <txr@alumni.caltech.edu> - 2011-06-28 16:03 -0700

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