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Printing like palindrome

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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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#109663

Ben Bacarisse <ben.usenet@bsb.me.uk> writes:
>scott@slp53.sl.home (Scott Lurndal) writes:
>

>> $ 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.

For EBCDIC, yes all the alpha characters have the high-order bit
set.  For ASCII the values that pass the validity checks will not
be greater than 0x7f.

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#109676

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

> Ben Bacarisse <ben.usenet@bsb.me.uk> writes:
>>scott@slp53.sl.home (Scott Lurndal) writes:
>>
>
>>> $ 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.
>
> For EBCDIC, yes all the alpha characters have the high-order bit
> set.  For ASCII the values that pass the validity checks will not
> be greater than 0x7f.

But the same applies to the validity check.  You can't be sure that
isalpha(*cp) is not being passed a negative value.

-- 
Ben.

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#109693

On Wed, 10 May 2017 13:21:28 GMT, scott@slp53.sl.home (Scott Lurndal)
wrote:

>For EBCDIC, yes all the alpha characters have the high-order bit
>set.  For ASCII the values that pass the validity checks will not
>be greater than 0x7f.

On C compilers for EBCDIC systems, char defaults to unsigned char so
the high order bit is not a sign bit.

-- 
Remove del for email

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#109629

On 09/05/2017 11:59, arnuld wrote:
> Programs works fine, I just wanted suggestions for improvement:
>
>
> /* GlobalEdx interview Question, Real Life Practicial Code

> void printPalindrome(char c) ;

If it's for an interview, then I wouldn't call it a palindrome, because 
it isn't.

A palindrome is a word or phrase (or sometimes number) which spells out 
the same thing when the character sequence is reversed (usually ignoring 
spacing, punctuation and capitalisation).

This just prints a letter sequence, then in reverse, avoiding 
duplicating the letter in the middle.

> int getFirstLetter(char* p, char* pc);
>
>
> int main(int argc, char* argv[]){
>   char c;
>   if(2 != argc) {

Ugly. And the idiom is mainly intended for == not !=.

>     printf("Please provide 1 argument\n");

"Please enter a letter A to Z"

>   }
>   else
>     {
>       if(!getFirstLetter(argv[1], &c)) printPalindrome(c);
>       else printf("You did not enter a character. Enter uppercase
> character \n");
>     }
>   return 0;
> }
>
> /* If you get more than letter. Just pick up the first letter
>  *
>  */
> int getFirstLetter(char* p, char* pc) {
>   char temp = *p;
>
>   /* What if user puts an int or double, here we handle that ? */
>   if( ((temp >= 'A') && (temp <= 'Z')) ) {
>     *pc = temp;
>     return 0;
>   }
>   else return 1;
>  }

The program seems to work, but you spend a disproportionate amount of 
code verifying the input, which is just a letter from A to Z. And it's 
not verifying it too well as anything is accepted not just a single 
letter. (It doesn't work for lower case either, but that is slightly 
trickier.)

(Also, if you run it on Linux, and enter * or ?, it'll use the name of 
the first matching file encountered. But you can't do much about that.)

-- 
bartc

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#109651

bartc <bc@freeuk.com> wrote:

> On 09/05/2017 11:59, arnuld wrote:
> > Programs works fine, I just wanted suggestions for improvement:
> >
> > /* GlobalEdx interview Question, Real Life Practicial Code
> 
> > void printPalindrome(char c) ;
> 
> If it's for an interview, then I wouldn't call it a palindrome, because 
> it isn't.
> 
> A palindrome is a word or phrase (or sometimes number) which spells out 
> the same thing when the character sequence is reversed (usually ignoring 
> spacing, punctuation and capitalisation).
> 
> This just prints a letter sequence, then in reverse, avoiding 
> duplicating the letter in the middle.

Which is /ipso facto/ a palindrome. A meaningless one, but it is one.

Richard

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#109695

On Tuesday, May 9, 2017 at 1:27:59 PM UTC-7, Bart wrote:
> On 09/05/2017 11:59, arnuld wrote:
> > Programs works fine, I just wanted suggestions for improvement:
> >
> >
> > /* GlobalEdx interview Question, Real Life Practicial Code
> 
> > void printPalindrome(char c) ;
> 
> If it's for an interview, then I wouldn't call it a palindrome, because 
> it isn't.
> 
> A palindrome is a word or phrase (or sometimes number) which spells out 
> the same thing when the character sequence is reversed (usually ignoring 
> spacing, punctuation and capitalisation).
> 
> This just prints a letter sequence, then in reverse, avoiding 
> duplicating the letter in the middle.
> 
> > int getFirstLetter(char* p, char* pc);
> >
> >
> > int main(int argc, char* argv[]){
> >   char c;
> >   if(2 != argc) {
> 
> Ugly. And the idiom is mainly intended for == not !=.
> 
> >     printf("Please provide 1 argument\n");
> 
> "Please enter a letter A to Z"
> 
> >   }
> >   else
> >     {
> >       if(!getFirstLetter(argv[1], &c)) printPalindrome(c);
> >       else printf("You did not enter a character. Enter uppercase
> > character \n");
> >     }
> >   return 0;
> > }
> >
> > /* If you get more than letter. Just pick up the first letter
> >  *
> >  */
> > int getFirstLetter(char* p, char* pc) {
> >   char temp = *p;
> >
> >   /* What if user puts an int or double, here we handle that ? */
> >   if( ((temp >= 'A') && (temp <= 'Z')) ) {
> >     *pc = temp;
> >     return 0;
> >   }
> >   else return 1;
> >  }
> 
> The program seems to work, but you spend a disproportionate amount of 
> code verifying the input, which is just a letter from A to Z. And it's 
> not verifying it too well as anything is accepted not just a single 
> letter. (It doesn't work for lower case either, but that is slightly 
> trickier.)
> 
> (Also, if you run it on Linux, and enter * or ?, it'll use the name of 
> the first matching file encountered. But you can't do much about that.)
> 
> -- 

For whatever reasons, I've followed this braindead crap. Anyways, I have a hard time believing that these are actual interview questions. This is because, at least in my limited experience, every major software firm that I've interviewed with asked programming questions that were far far more difficult. In some cases, C wasn't always the correct way to solve the problem. Ie, I had to break out the Erlang.

So either this fool is making things up or he is interviewing for a tech position at a software firm located in someone's mothers basement?

Who knows. I could be wrong.

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#109655

On 09/05/2017 11:59, arnuld wrote:

>       if(!getFirstLetter(argv[1], &c)) printPalindrome(c);
>       else printf("You did not enter a character. Enter uppercase
> character \n");
>     }
>   return 0;
> }

I didn't look at the actual code too closely before. This looks untidy. 
It seems that getFirstLetter() returns a status 0 for success, and 1 for 
failure, with the letter itself via a pointer. But that's not so obvious 
from looking at this. It's also overkill.

I think better would be:

    if (c = getFirstLetter(argv[1]))
        printPalindrome(c);
    else
        ... deal with error...

With c == 0 signifying an error.

(And since the checking done by getFirstLetter is perfunctory, the 
following would do:

   c = *argv[1];

   if (c >= 'A' && c <= 'Z')       // or any of a million other ways
      printPalindrome(c);


Personally I would also arrange it to get the verification out of the 
way first, then I have my verified input c, and can do what I need to do 
with it without still being embroiled in user interface stuff.)

-- 
bartc

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#109816

I do not like
void printPalindrome(char c)
But I like
void printPalindrome(int c)
Or
printPalindrome(c){...}

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