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

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On 06/23/11 10:56 PM, 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.
>
>
> #include<stdio.h>
> #include<string.h>
>
> int strend(const char* s1, const char* s2);
>
>
> int main(void)
> {
>    const char* arr1 = "comp.lang.c";
>    const char* arr2 = "comp.lang.";
>
>    printf("strend(%s, %s) = %d\n", arr1, arr2, strend(arr1, arr2));

You should add test cases for the conditions you are testing as well as 
some matches.

>    return 0;
> }
>
>
> /* return 1 if str2 occurs at the end of str1, zero otherwise */
> int strend(const char* str1, const char* str2)
> {
>    int ret;
>
>    /* If one of arguments is NULL, there is no pint in going next */
>    if(NULL == str1 || NULL == str2)
>      {
>        ret = 0;
>      }
>    else if(strlen(str1)<  strlen(str2))

I would do this test last, after you assign the strlen results to len1 
and len2 to avoid calling strlen twice for each string.

>      {
>        ret = 0;
>      }
>    else if ('\0' == *str1&&  '\0' == *str2)
>      {
>        ret = 1;
>      }
>    else
>      {
>        size_t len1 = strlen(str1);
>        size_t len2 = strlen(str2);
>        const char* tmp1 = str1 + len1 - 1;
>        const char* tmp2 = str2 + len2 - 1;
>        size_t count = 0;
>        for(; *tmp1 == *tmp2&&  count<  len2; --tmp1, --tmp2, ++count)
> 	;
> 	
>        if(count == len2&&  *++tmp1 == *++tmp2) ret = 1;
>        else ret = 0;
>      }
>
>    return ret;
> }
>
> ==================== OUTPUT =========================
> [arnuld@dune C]$ gcc -ansi -pedantic -Wall -Wextra strend.c
> [arnuld@dune C]$ ./a.out
> strend(comp.lang.c, comp.lang.) = 0
> [arnuld@dune C]$
>
>
>


-- 
Ian Collins

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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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