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Re: Printing like palindrome

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scott@slp53.sl.home (Scott Lurndal) writes:

> arnuld <sunrise@invalid.address> writes:
>>Programs works fine, I just wanted suggestions for improvement:
>>
>>
>>/* GlobalEdx interview Question, Real Life Practicial Code 
>> * 
>> * If a user enters D then write a program to print like this:   
>> *  A B C D C B A
>> * If user Enters J or Z then it should print till J or Z 
>> * like above. Program should work for every letter of English
>> *
>> */
>
> Seems unnecessarily complex:
>
> $ cat /tmp/a.c
> #include <ctype.h>
> #include <stdio.h>
> #include <string.h>
>
> int
> main(int argc, const char **argv, const char **envp)
> {
>     const char *cp = argv[1];
>     if ((argc < 2) || (strlen(cp) > 1) || !isalpha(*cp)) {
>         printf("Argument to '%s' must be a single alphabetic character, not '%s'\n",
>                argv[0], argv[1]?argv[1]:"<empty>");
>         return 1;
>     }
>
>     for(char c = 'A'; c != toupper(*cp); c++) printf("%c", c);
>     for(char c = toupper(*cp); c >= 'A'; --c) printf("%c", c);
>     putc('\n', stdout);
>     return 0;
> }

There's the nasty issue that toupper takes an int and is only defined
for positive arguments (and EOF) whereas *cp may be negative.

I'd use:

  int target = (unsigned char)*argv[1];

and later

  for (int c = 'A'; ...)

Interestingly, if you write

  if (isupper(c)) putchar(c);

in the body of the loops the program will work with EBCDIC and more.

-- 
Ben.

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Printing like palindrome arnuld <sunrise@invalid.address> - 2017-05-09 10:59 +0000
  Re: Printing like palindrome Barry Schwarz <schwarzb@dqel.com> - 2017-05-09 04:26 -0700
    Re: Printing like palindrome Robert Wessel <robertwessel2@yahoo.com> - 2017-05-09 14:10 -0500
      Re: Printing like palindrome Keith Thompson <kst-u@mib.org> - 2017-05-09 12:33 -0700
        Re: Printing like palindrome Richard Heathfield <rjh@cpax.org.uk> - 2017-05-09 23:05 +0100
          Re: Printing like palindrome raltbos@xs4all.nl (Richard Bos) - 2017-05-10 10:25 +0000
            Re: Printing like palindrome Richard Heathfield <rjh@cpax.org.uk> - 2017-05-10 11:44 +0100
          Re: Printing like palindrome Keith Thompson <kst-u@mib.org> - 2017-05-10 09:48 -0700
            Re: Printing like palindrome Gareth Owen <gwowen@gmail.com> - 2017-05-10 18:59 +0100
        Re: Printing like palindrome arnuld <sunrise@invalid.address> - 2017-05-12 07:14 +0000
      Re: Printing like palindrome arnuld <sunrise@invalid.address> - 2017-05-12 07:44 +0000
    Re: Printing like palindrome arnuld <sunrise@invalid.address> - 2017-05-12 07:20 +0000
      Re: Printing like palindrome Keith Thompson <kst-u@mib.org> - 2017-05-12 08:49 -0700
        Re: Printing like palindrome arnuld <sunrise@invalid.address> - 2017-05-14 02:01 +0000
  Re: Printing like palindrome mark.bluemel@gmail.com - 2017-05-09 07:13 -0700
    Re: Printing like palindrome scott@slp53.sl.home (Scott Lurndal) - 2017-05-09 14:59 +0000
      Re: Printing like palindrome Keith Thompson <kst-u@mib.org> - 2017-05-09 08:27 -0700
      Re: Printing like palindrome Barry Schwarz <schwarzb@dqel.com> - 2017-05-09 10:40 -0700
  Re: Printing like palindrome scott@slp53.sl.home (Scott Lurndal) - 2017-05-09 14:38 +0000
    Re: Printing like palindrome Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-05-09 22:48 +0100
      Re: Printing like palindrome scott@slp53.sl.home (Scott Lurndal) - 2017-05-10 13:21 +0000
        Re: Printing like palindrome Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-05-10 15:45 +0100
        Re: Printing like palindrome Barry Schwarz <schwarzb@dqel.com> - 2017-05-10 10:26 -0700
  Re: Printing like palindrome bartc <bc@freeuk.com> - 2017-05-09 21:28 +0100
    Re: Printing like palindrome raltbos@xs4all.nl (Richard Bos) - 2017-05-10 10:27 +0000
    Re: Printing like palindrome Chad <cdalten@gmail.com> - 2017-05-10 10:39 -0700
  Re: Printing like palindrome bartc <bc@freeuk.com> - 2017-05-10 12:54 +0100
  Printing like palindrome asetofsymbols@gmail.com - 2017-05-12 02:32 -0700

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