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Concatenation of strings without string.h

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Join Date: Oct 2007

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weasel7711 weasel7711 is offline

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Re: Concatenation of strings without string.h

#11

Nov 1st, 2007

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Originally Posted by Ancient Dragon

This function will convert the entire sentence to all upper-case. Hope that's what you want to do.

I just wanted to change the first character in the sentence to uppercase, what would I change to do that?

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Ptolemy

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Re: Concatenation of strings without string.h

#12

Nov 1st, 2007

>I just wanted to change the first character in the sentence to
>uppercase, what would I change to do that?
Don't call toupper on every character, just on the first one:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
void printSentence(char *sentPtr){
    char *sent = sentPtr;
 
    *sent = toupper((unsigned char)*sent);
 
    while(*sent)
    {
       ++sent;
    }
 
    *sent++ = '.';
    *sent = 0;
    cout << sentPtr << endl;
}
void printSentence(char *sentPtr){
    char *sent = sentPtr;

    *sent = toupper((unsigned char)*sent);

    while(*sent)
    {
       ++sent;
    }

    *sent++ = '.';
    *sent = 0;
    cout << sentPtr << endl;
}

Last edited by Ptolemy; Nov 1st, 2007 at 3:31 pm.

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Re: Concatenation of strings without string.h

#13

Nov 6th, 2007

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Originally Posted by Ptolemy

Don't call toupper on every character, just on the first one:
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C++ Syntax (Toggle Plain Text)
    *sent = toupper((unsigned char)*sent);
*sent = toupper((unsigned char)*sent);

I'm slightly confused as to why the unsigned char makes a difference?

On a side note: I spoke to my professor last week and apparently we are able to use strcat, so I started using that and it fixed the program and its been submitted, however i'd still like to know how to concatenate using my own function just for personal use and education.

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Narue

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Re: Concatenation of strings without string.h

#14

Nov 6th, 2007

>I'm slightly confused as to why the unsigned char makes a difference?
toupper takes an integer parameter, but that integer is required to be either EOF or in the range of unsigned char. Because sent holds values that you can't be sure fit in that range, a cast forces the range to avoid undefined behavior.

>however i'd still like to know how to concatenate using
>my own function just for personal use and education.
Here's how one might implement strcat:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
char *strcat ( char * dst, const char * src )
{
  char *save = dst;
 
  while ( *dst != '\0' )
    ++dst;
 
  while ( ( *dst++ = *src++ ) != '\0' )
    ;
 
  return save;
}
char *strcat ( char * dst, const char * src )
{
  char *save = dst;

  while ( *dst != '\0' )
    ++dst;

  while ( ( *dst++ = *src++ ) != '\0' )
    ;

  return save;
}