Thread: [Dev-C++] String Functions

Hi All,

Can anyone help me with a couple of functions I am having problems with =
in the String class I am writing?  (It runs.)

The following code is supposed to return the first instance of a =
character, but is returning the last (11):

int String::firstcharfind (const char& charfind) const  //#2
{  size_t i;
   int position;
   for (i =3D 0; i < current_length; i++)
   {
      if (sequence[i] =3D=3D charfind)
         position =3D i;
   }
   return position;
}

This is called by:=20

//#2
   char testing [28] =3D "Delete the extra word word.";
   String demostring (testing);
   cout << demostring.firstcharfind ('e') << endl;

The second function is supposed to delete one of the "word"s in the =
above function:

bool String::charsdelete (int begin, int end)  //#4
{
   int i;
   if ((begin < 0) || (end > current_length) || (begin > end))
      return false;
   int partdeleted =3D (end - begin) + 1;
   for (i =3D begin; i <=3D current_length - partdeleted ; i++)
   {
      sequence[i] =3D sequence[partdeleted + 1];
   }
   current_length =3D current_length - partdeleted;
   allocated =3D allocated - partdeleted;
   return true;
}

It's called by:

//#4
   demostring.charsdelete (18, 22);
   cout << demostring << endl;

The output is:

Delete the extra w      ord.

I'd appreciate any help anyone can give - it's the last class for my =
Data Structures class.

TIA,

Linda

Sorry, none of this was tested but, it may give you a
hand. 

1) You do not terminate the loop once you find the
first instance. You also don't handle the case where
the character does not exist. TRY:

int String::firstcharfind (const char& charfind) const
 //#2
{  
	int i;
	for (i = 0; i < current_length; i++)
    	{
       	      if (sequence[i] == charfind)
          		return i;
    	}
    	return -1;
}

2) I am assuming your string arrays are NULL
terminiated.
TRY:

bool String::charsdelete (int begin, int end)  //#4
{
	if ((begin < 0) || 
	    (begin >= current_length) ||
	    (end >= current_length) ||
            (begin > end)
		return false;
	
	int lengthToMove = (current_length - end); 
	

memcpy(&sequence[begin],&sequence[end+1],lengthToMove);
	
	current_length = current_length - ((end - begin) +
1);

	return true;
}






--- Linda Hohenstein <lz...@sp...> wrote:
> Hi All,
> 
> Can anyone help me with a couple of functions I am
> having problems with in the String class I am
> writing?  (It runs.)
> 
> The following code is supposed to return the first
> instance of a character, but is returning the last
> (11):
> 
> int String::firstcharfind (const char& charfind)
> const  //#2
> {  size_t i;
>    int position;
>    for (i = 0; i < current_length; i++)
>    {
>       if (sequence[i] == charfind)
>          position = i;
>    }
>    return position;
> }
> 
> This is called by: 
> 
> //#2
>    char testing [28] = "Delete the extra word
> word.";
>    String demostring (testing);
>    cout << demostring.firstcharfind ('e') << endl;
> 
> The second function is supposed to delete one of the
> "word"s in the above function:
> 
> bool String::charsdelete (int begin, int end)  //#4
> {
>    int i;
>    if ((begin < 0) || (end > current_length) ||
> (begin > end))
>       return false;
>    int partdeleted = (end - begin) + 1;
>    for (i = begin; i <= current_length - partdeleted
> ; i++)
>    {
>       sequence[i] = sequence[partdeleted + 1];
>    }
>    current_length = current_length - partdeleted;
>    allocated = allocated - partdeleted;
>    return true;
> }
> 
> It's called by:
> 
> //#4
>    demostring.charsdelete (18, 22);
>    cout << demostring << endl;
> 
> The output is:
> 
> Delete the extra w      ord.
> 
> I'd appreciate any help anyone can give - it's the
> last class for my Data Structures class.
> 
> TIA,
> 
> Linda
> 
> 
> 
> 
> 


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Thanks Michael and Kurt!

Michael, is this:

"You also don't handle the case where
the character does not exist."

left to the user to take care of?

TIA,

Linda

-----------------------------------------
----- Original Message ----- 
From: "Michael Potter" <mdp...@ya...>
To: <dev...@li...>
Sent: Tuesday, May 01, 2001 5:02 PM
Subject: Re: [Dev-C++] String Functions


> Sorry, none of this was tested but, it may give you a
> hand. 
> 
> 1) You do not terminate the loop once you find the
> first instance. You also don't handle the case where
> the character does not exist. TRY:
> 
> int String::firstcharfind (const char& charfind) const
>  //#2
> {  
> int i;
> for (i = 0; i < current_length; i++)
>     {
>              if (sequence[i] == charfind)
>           return i;
>     }
>     return -1;
> }
> 
> 2) I am assuming your string arrays are NULL
> terminiated.
> TRY:
> 
> bool String::charsdelete (int begin, int end)  //#4
> {
> if ((begin < 0) || 
>     (begin >= current_length) ||
>     (end >= current_length) ||
>             (begin > end)
> return false;
> 
> int lengthToMove = (current_length - end); 
> 
> 
> memcpy(&sequence[begin],&sequence[end+1],lengthToMove);
> 
> current_length = current_length - ((end - begin) +
> 1);
> 
> return true;
> }
> 
> 
> 
> 
> 
> 
> --- Linda Hohenstein <lz...@sp...> wrote:
> > Hi All,
> > 
> > Can anyone help me with a couple of functions I am
> > having problems with in the String class I am
> > writing?  (It runs.)
> > 
> > The following code is supposed to return the first
> > instance of a character, but is returning the last
> > (11):
> > 
> > int String::firstcharfind (const char& charfind)
> > const  //#2
> > {  size_t i;
> >    int position;
> >    for (i = 0; i < current_length; i++)
> >    {
> >       if (sequence[i] == charfind)
> >          position = i;
> >    }
> >    return position;
> > }
> > 
> > This is called by: 
> > 
> > //#2
> >    char testing [28] = "Delete the extra word
> > word.";
> >    String demostring (testing);
> >    cout << demostring.firstcharfind ('e') << endl;
> > 
> > The second function is supposed to delete one of the
> > "word"s in the above function:
> > 
> > bool String::charsdelete (int begin, int end)  //#4
> > {
> >    int i;
> >    if ((begin < 0) || (end > current_length) ||
> > (begin > end))
> >       return false;
> >    int partdeleted = (end - begin) + 1;
> >    for (i = begin; i <= current_length - partdeleted
> > ; i++)
> >    {
> >       sequence[i] = sequence[partdeleted + 1];
> >    }
> >    current_length = current_length - partdeleted;
> >    allocated = allocated - partdeleted;
> >    return true;
> > }
> > 
> > It's called by:
> > 
> > //#4
> >    demostring.charsdelete (18, 22);
> >    cout << demostring << endl;
> > 
> > The output is:
> > 
> > Delete the extra w      ord.
> > 
> > I'd appreciate any help anyone can give - it's the
> > last class for my Data Structures class.
> > 
> > TIA,
> > 
> > Linda
> > 
> > 
> > 
> > 
> > 
> 
> 
> __________________________________________________
> Do You Yahoo!?
> Yahoo! Auctions - buy the things you want at great prices
> http://auctions.yahoo.com/
> 
> _______________________________________________
> Dev-cpp-users mailing list
> Dev...@li...
> http://lists.sourceforge.net/lists/listinfo/dev-cpp-users

The caller should have some way to detect the case. My
function returned a '-1' in this case. The caller
should test for this result.

--- Linda Hohenstein <lz...@sp...> wrote:
> Thanks Michael and Kurt!
> 
> Michael, is this:
> 
> "You also don't handle the case where
> the character does not exist."
> 
> left to the user to take care of?
> 
> TIA,
> 
> Linda
> 
> -----------------------------------------
> ----- Original Message ----- 
> From: "Michael Potter" <mdp...@ya...>
> To: <dev...@li...>
> Sent: Tuesday, May 01, 2001 5:02 PM
> Subject: Re: [Dev-C++] String Functions
> 
> 
> > Sorry, none of this was tested but, it may give
> you a
> > hand. 
> > 
> > 1) You do not terminate the loop once you find the
> > first instance. You also don't handle the case
> where
> > the character does not exist. TRY:
> > 
> > int String::firstcharfind (const char& charfind)
> const
> >  //#2
> > {  
> > int i;
> > for (i = 0; i < current_length; i++)
> >     {
> >              if (sequence[i] == charfind)
> >           return i;
> >     }
> >     return -1;
> > }
> > 
> > 2) I am assuming your string arrays are NULL
> > terminiated.
> > TRY:
> > 
> > bool String::charsdelete (int begin, int end) 
> //#4
> > {
> > if ((begin < 0) || 
> >     (begin >= current_length) ||
> >     (end >= current_length) ||
> >             (begin > end)
> > return false;
> > 
> > int lengthToMove = (current_length - end); 
> > 
> > 
> >
>
memcpy(&sequence[begin],&sequence[end+1],lengthToMove);
> > 
> > current_length = current_length - ((end - begin) +
> > 1);
> > 
> > return true;
> > }
> > 
> > 
> > 
> > 
> > 
> > 
> > --- Linda Hohenstein <lz...@sp...> wrote:
> > > Hi All,
> > > 
> > > Can anyone help me with a couple of functions I
> am
> > > having problems with in the String class I am
> > > writing?  (It runs.)
> > > 
> > > The following code is supposed to return the
> first
> > > instance of a character, but is returning the
> last
> > > (11):
> > > 
> > > int String::firstcharfind (const char& charfind)
> > > const  //#2
> > > {  size_t i;
> > >    int position;
> > >    for (i = 0; i < current_length; i++)
> > >    {
> > >       if (sequence[i] == charfind)
> > >          position = i;
> > >    }
> > >    return position;
> > > }
> > > 
> > > This is called by: 
> > > 
> > > //#2
> > >    char testing [28] = "Delete the extra word
> > > word.";
> > >    String demostring (testing);
> > >    cout << demostring.firstcharfind ('e') <<
> endl;
> > > 
> > > The second function is supposed to delete one of
> the
> > > "word"s in the above function:
> > > 
> > > bool String::charsdelete (int begin, int end) 
> //#4
> > > {
> > >    int i;
> > >    if ((begin < 0) || (end > current_length) ||
> > > (begin > end))
> > >       return false;
> > >    int partdeleted = (end - begin) + 1;
> > >    for (i = begin; i <= current_length -
> partdeleted
> > > ; i++)
> > >    {
> > >       sequence[i] = sequence[partdeleted + 1];
> > >    }
> > >    current_length = current_length -
> partdeleted;
> > >    allocated = allocated - partdeleted;
> > >    return true;
> > > }
> > > 
> > > It's called by:
> > > 
> > > //#4
> > >    demostring.charsdelete (18, 22);
> > >    cout << demostring << endl;
> > > 
> > > The output is:
> > > 
> > > Delete the extra w      ord.
> > > 
> > > I'd appreciate any help anyone can give - it's
> the
> > > last class for my Data Structures class.
> > > 
> > > TIA,
> > > 
> > > Linda
> > > 
> > > 
> > > 
> > > 
> > > 
> > 
> > 
> > __________________________________________________
> > Do You Yahoo!?
> > Yahoo! Auctions - buy the things you want at great
> prices
> > http://auctions.yahoo.com/
> > 
> > _______________________________________________
> > Dev-cpp-users mailing list
> > Dev...@li...
> >
>
http://lists.sourceforge.net/lists/listinfo/dev-cpp-users
> 
> 
> _______________________________________________
> Dev-cpp-users mailing list
> Dev...@li...
>
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Try this version of "charsdelete".

I assume: i) sequence is null terminated, ii) current_length is the
number of chars in sequence (i.e. if sequence is  "delete the extra
word word." current_length is 27).

bool String::charsdelete (int begin, int end)
{
    if (begin < 0 || begin >= current_length ||  end >= current_length
||  begin > end)
        return false;

    int partdeleted = end - begin + 1;

    while (end < current_length) // moves also the trailing '\0'
        sequence[begin++] = sequence[++end];

    current_length -= partdeleted;
    allocated -= partdeleted; // I wonder why you keep track of
allocated memory
    return true;
}

gisan


----- Original Message -----
From: "Michael Potter" <mdp...@ya...>
To: <dev...@li...>
Sent: Wednesday, May 02, 2001 3:53 PM
Subject: Re: [Dev-C++] String Functions


The caller should have some way to detect the case. My
function returned a '-1' in this case. The caller
should test for this result.

--- Linda Hohenstein <lz...@sp...> wrote:
> Thanks Michael and Kurt!
>
> Michael, is this:
>
> "You also don't handle the case where
> the character does not exist."
>
> left to the user to take care of?
>
> TIA,
>
> Linda
>
> -----------------------------------------
> ----- Original Message -----
> From: "Michael Potter" <mdp...@ya...>
> To: <dev...@li...>
> Sent: Tuesday, May 01, 2001 5:02 PM
> Subject: Re: [Dev-C++] String Functions
>
>
> > Sorry, none of this was tested but, it may give
> you a
> > hand.
> >
> > 1) You do not terminate the loop once you find the
> > first instance. You also don't handle the case
> where
> > the character does not exist. TRY:
> >
> > int String::firstcharfind (const char& charfind)
> const
> >  //#2
> > {
> > int i;
> > for (i = 0; i < current_length; i++)
> >     {
> >              if (sequence[i] == charfind)
> >           return i;
> >     }
> >     return -1;
> > }
> >
> > 2) I am assuming your string arrays are NULL
> > terminiated.
> > TRY:
> >
> > bool String::charsdelete (int begin, int end)
> //#4
> > {
> > if ((begin < 0) ||
> >     (begin >= current_length) ||
> >     (end >= current_length) ||
> >             (begin > end)
> > return false;
> >
> > int lengthToMove = (current_length - end);
> >
> >
> >
>
memcpy(&sequence[begin],&sequence[end+1],lengthToMove);
> >
> > current_length = current_length - ((end - begin) +
> > 1);
> >
> > return true;
> > }
> >
> >
> >
> >
> >
> >
> > --- Linda Hohenstein <lz...@sp...> wrote:
> > > Hi All,
> > >
> > > Can anyone help me with a couple of functions I
> am
> > > having problems with in the String class I am
> > > writing?  (It runs.)
> > >
> > > The following code is supposed to return the
> first
> > > instance of a character, but is returning the
> last
> > > (11):
> > >
> > > int String::firstcharfind (const char& charfind)
> > > const  //#2
> > > {  size_t i;
> > >    int position;
> > >    for (i = 0; i < current_length; i++)
> > >    {
> > >       if (sequence[i] == charfind)
> > >          position = i;
> > >    }
> > >    return position;
> > > }
> > >
> > > This is called by:
> > >
> > > //#2
> > >    char testing [28] = "Delete the extra word
> > > word.";
> > >    String demostring (testing);
> > >    cout << demostring.firstcharfind ('e') <<
> endl;
> > >
> > > The second function is supposed to delete one of
> the
> > > "word"s in the above function:
> > >
> > > bool String::charsdelete (int begin, int end)
> //#4
> > > {
> > >    int i;
> > >    if ((begin < 0) || (end > current_length) ||
> > > (begin > end))
> > >       return false;
> > >    int partdeleted = (end - begin) + 1;
> > >    for (i = begin; i <= current_length -
> partdeleted
> > > ; i++)
> > >    {
> > >       sequence[i] = sequence[partdeleted + 1];
> > >    }
> > >    current_length = current_length -
> partdeleted;
> > >    allocated = allocated - partdeleted;
> > >    return true;
> > > }
> > >
> > > It's called by:
> > >
> > > //#4
> > >    demostring.charsdelete (18, 22);
> > >    cout << demostring << endl;
> > >
> > > The output is:
> > >
> > > Delete the extra w      ord.
> > >
> > > I'd appreciate any help anyone can give - it's
> the
> > > last class for my Data Structures class.
> > >
> > > TIA,
> > >
> > > Linda
> > >
> > >
> > >
> > >
> > >
> >
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Yahoo! Auctions - buy the things you want at great
> prices
> > http://auctions.yahoo.com/
> >
> > _______________________________________________
> > Dev-cpp-users mailing list
> > Dev...@li...
> >
>
http://lists.sourceforge.net/lists/listinfo/dev-cpp-users
>
>
> _______________________________________________
> Dev-cpp-users mailing list
> Dev...@li...
>
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