C / C++ / MFC

Re: how to delete specific elements in a char pointer

10-Oct-07 23:17

are you using MFC?
i.e. CString

Suggestion to the members:
prefix your main thread subject with [SOLVED] if it is solved.
chandu.

toxcct10-Oct-07 23:22

toxcct

10-Oct-07 23:22

chandu004 wrote:
are you using MFC?

the OP specified explicitely that he was using a unsigned char *String.
so 1) read the questions
and 2) before giving advices to the forum members, stick to the rules yourself Poke tongue | ;-P

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Re: how to delete specific elements in a char pointer

chandu00411-Oct-07 4:04

Re: how to delete specific elements in a char pointer

11-Oct-07 4:04

so 1) read the questions
and 2) before giving advices to the forum members, stick to the rules yourself

Suggestion to the members:
prefix your main thread subject with [SOLVED] if it is solved.
chandu.

Priya_Sundar10-Oct-07 23:45

Re: how to delete specific elements in a char pointer

10-Oct-07 23:45

Thanks for your concern.

Yes i use MFC.

By your question, I got an idea to convert it into a CString and apply delete and then save it back - something like this;

<br />
    unsigned char *String;<br />
	<br />
    CString cString,result;<br />
    cString="{abcdef}";<br />
    int n=cString.GetLength();<br />
    result=cString.Mid(1,n-2);<br />
<br />
    String = (BSTR)rest; <br />

However, here i am not able to store it back to 'String'. i am getting various compiler errors like

" error C2440: 'type cast' : cannot convert from 'class CString' to 'unsigned short *'
No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called "

Need help in typecasting in the last line.

Priya Sundar

jhwurmbach11-Oct-07 0:46

Re: how to delete specific elements in a char pointer

11-Oct-07 0:46

What is rest, and why are you trying to cast it into a BSTR, when what you wand is a unsigned char*?
And why unsigned char? Thats uncommon.

Though I speak with the tongues of men and of angels, and have not money, I am become as a sounding brass, or a tinkling cymbal.
George Orwell, "Keep the Aspidistra Flying", Opening words

Priya_Sundar11-Oct-07 1:35

Re: how to delete specific elements in a char pointer

11-Oct-07 1:35

Refer the link

http://www.codeproject.com/script/comments/forums.asp?forumid=1647&select=2266651&df=100&fr=76[^]

you will get my exact requirement!

Thankyou.

Priya Sundar

jhwurmbach11-Oct-07 1:50

Re: how to delete specific elements in a char pointer

11-Oct-07 1:50

You want to convert a GUID to a String?
Try somthing like this:

void GetFormattedGuid( const GUID& guid, CString& rString)
{
  // use appropriate formatting string
  const CString strFormat(_T("%08lX-%04X-%04x-%02X%02X-%02X%02X%02X%02X%02X%02X"));

  // then format into destination
  rString.Format(strFormat,
    guid.Data1, guid.Data2, guid.Data3,
    guid.Data4[0], guid.Data4[1], guid.Data4[2], guid.Data4[3],
    guid.Data4[4], guid.Data4[5], guid.Data4[6], m_guid.Data4[7],
  );
}

When you are using MFC anyway, there is no point in not using it to help you.

Though I speak with the tongues of men and of angels, and have not money, I am become as a sounding brass, or a tinkling cymbal.
George Orwell, "Keep the Aspidistra Flying", Opening words

Priya_Sundar11-Oct-07 2:41

Re: how to delete specific elements in a char pointer

11-Oct-07 2:41

Sorry, i want to convert a character array to GUID

<br />
bool CTcpIpPropertiesChangerApp::UUidConversion()<br />
{<br />
   char szValue[MAX_GUID_STRING_LEN];<br />
<br />
   szValue={A89377EA-D4ED-4A03-A37F-4A9DE785E1A9};//This value i get from a for loop function<br />
<br />
   unsigned char *GuidString=new unsigned char[MAX_GUID_STRING_LEN];<br />
   GuidString[MAX_GUID_STRING_LEN - 2] = _T('\0');<br />
<br />
   for(int l=0;l<MAX_GUID_STRING_LEN;l++)<br />
     GuidString[l] = szValue[l];<br />
<br />
   GUID ret = { 0 };//If GUID is replaced by UUID makes no difference during execution<br />
   if(UuidFromString(GuidString,&ret)==RPC_S_OK)<br />
   {<br />
	delete GuidString;<br />
	return true;<br />
   }<br />
   else<br />
     return false;<br />
}<br />

Now this function is always returning false as UuidFromString is always returning RPC_S_INVALID_STRING_UUID telling that the string UUID/GUID 'GuidString' is invalid.

Priya Sundar

jhwurmbach11-Oct-07 3:31

Re: how to delete specific elements in a char pointer

11-Oct-07 3:31

Priya_Sundar wrote:
Now this function is always returning false as UuidFromString is always returning RPC_S_INVALID_STRING_UUID telling that the string UUID/GUID 'GuidString' is invalid.

Wow.
This is the first time you give a proper error report.
You never mentioned this function before.

OK. For me

#include "stdafx.h"

#include <atlstr.h>
#include <iostream>
#include <RPC.h>

#pragma comment( lib, "Rpcrt4")

int _tmain(int argc, _TCHAR* argv[])
{
  const char szValue[] = "{A89377EA-D4ED-4A03-A37F-4A9DE785E1A9}";//This is some parameter

  // Here, anything after the first up to the last but one character gets assigned to the CString
  CString szGuidString( szValue+1, strlen(szValue)-2);
  GUID ret = { 0 };
  const RPC_STATUS status = UuidFromString( (unsigned char*)(LPCTSTR)szGuidString, &ret);
  if( status == RPC_S_OK)
  {
    ...
  }
  else
  {
    ...
  }

  return system("pause");
}

worked.
Note the double cast in the UuidFromString-call: It is used to get the raw const TCHAR* from the CString, and the other cast tells the compiler "Shut up and take this as if it were unsigneds!".
That is not Unicode-compatible. Under Unicode, the CString would hold wchar_ts, and by forcing the compiler to tread them as a string of unsigned chars, anything could happen.

Though I speak with the tongues of men and of angels, and have not money, I am become as a sounding brass, or a tinkling cymbal.
George Orwell, "Keep the Aspidistra Flying", Opening words

Priya_Sundar11-Oct-07 1:42

Re: how to delete specific elements in a char pointer

11-Oct-07 1:42

sorry rest is 'result'

and i started trying with (unsigned char *) and ended up with the error

"error C2440: 'type cast' : cannot convert from 'class CString' to 'unsigned char *'"

so i started using various things like BSTR. And that is where i need help!

Priya Sundar

toxcct11-Oct-07 1:48

toxcct

11-Oct-07 1:48

cast to (LPCTSTR) instead

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Re: how to delete specific elements in a char pointer

jhwurmbach11-Oct-07 1:58

Re: how to delete specific elements in a char pointer

11-Oct-07 1:58

The normal plain old C-String most function want is char* or const char*. That is a signed type.
Microsoft uses a specific macro named TCHAR, which boils down to char* in non-unicode and to (2 Byte-)wchar_t in Unicode builds. Very handy.
Likewise, TSTR denotes a null-terminated string consisting of TCHAR.

A pointer to a constant string consisting of TCHAR is called a LPCTSTR (long pointer to constant TSTR).
The CString-class wraps the TCHARs from you, and has a conversion operator to be used in place of a constant TSTR.

So, when you stop using unsigned char and start using TCHAR, you problems will go away automagically.

Though I speak with the tongues of men and of angels, and have not money, I am become as a sounding brass, or a tinkling cymbal.
George Orwell, "Keep the Aspidistra Flying", Opening words

David Crow11-Oct-07 3:45

David Crow

11-Oct-07 3:45

Priya_Sundar wrote:
However, here i am not able to store it back to 'String'.

Why does that surprise you? No memory has been allocated for String. As it stands now, it points to wherever. try:

String = new unsigned char[result.GetLength() + 1];
strcpy(String, result);

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Re: how to delete specific elements in a char pointer [modified]

chandu00411-Oct-07 4:01

Re: how to delete specific elements in a char pointer

11-Oct-07 4:01

sorry for the delayed post.
i was actually in a meeting.
to your problem,

Priya_Sundar wrote:
However, here i am not able to store it back to 'String'. i am getting various compiler errors like

the quickest solution is ,
for(int i=0;i less than n;i++)

{
String[i]=cString.Getat(i);//or cString[i] must also should work.
}

gud luck.

-- modified at 10:08 Thursday 11th October, 2007

Suggestion to the members:
prefix your main thread subject with [SOLVED] if it is solved.
chandu.

chandu00411-Oct-07 4:05

Re: how to delete specific elements in a char pointer

11-Oct-07 4:05

i think the topic got far diverted here.

Matthew Faithfull10-Oct-07 23:23

Matthew Faithfull

10-Oct-07 23:23

OK firstly we need to establish the meaning of 'delete' in this context. In C++ delete tends to means 'free the memory'. You certainly can't 'free the memory' currently being used by the '{' and the '}' so in C++ terms you can't 'delete' the first and last characters.
What you want is to end up with String pointing at "abcdef". You could do this with 2 lines

<br />
String++;<br />
String[6] = '\0';<br />

This will make the charatcer pointer point at the next character and then 'blank out' the end '}' (which is 6 characters on from the 'a' that String now points at) by replacing it with a NULL

There is one problem with this of course. You now have no way to free the string memory as the original value of String is lost. If your string is on the heap you will need to solve this. Enjoy.

Nothing is exactly what it seems but everything with seems can be unpicked.

Re: how to delete specific elements in a char pointer

toxcct10-Oct-07 23:33

toxcct

10-Oct-07 23:33

use a temporary buffer and use the CRT function strcpy() to copy what you want in the origin string

or if you use C++, you'd better look into the std::string STL class

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Re: how to delete specific elements in a char pointer

Priya_Sundar10-Oct-07 23:48

Re: how to delete specific elements in a char pointer

10-Oct-07 23:48

i tried something like this

<br />
    ::string gidstring = String;<br />
    gidstring = gidstring.substr(1, gidstring.length() - 2);<br />

But ended up with compiler error:

"error C2039: 'string' : is not a member of '`global namespace''"

inspite of including the <string.h> header file.

how to proceed??

Priya Sundar

jhwurmbach11-Oct-07 0:48

Re: how to delete specific elements in a char pointer [modified]

11-Oct-07 0:48

why did you write ::string, thereby explicitly requesting string in the global namespace?
You probably wanted to write std::string.

Though I speak with the tongues of men and of angels, and have not money, I am become as a sounding brass, or a tinkling cymbal.
George Orwell, "Keep the Aspidistra Flying", Opening words

Nelek11-Oct-07 0:15

Nelek

11-Oct-07 0:15

What about...

unsigned char *srcString = "{abcdef}";
unsigned char *dstString = "";


memcpy (srcString+1, dstString, (srcString.length () - 2));

If it works you can still free the memory and delete the pointer avoiding the problem that Matthew said.
Up to that point you can work with *dstString as it was your original one.

Hope it helps

P.S. Im not sure if it works, I just asked about buffers and how to get parts of the memory two/three days ago, and this is something that I get from the answers I received.

-- modified at 6:29 Thursday 11th October, 2007

I forgot...

with the srcString + X you specify the first character you want without changing the "value" of where the pointer points.

at dsstString you can make the same leaving some intial chars unmodified adding X to his base adress

the last is the number of chars of the first string you wanna copy in the second

Greetings.

--------
M.D.V.

If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?

Help me to understand what I'm saying, and I'll explain it better to you

Wink | ;)

How to use InvokeHelper function in C++?

PhanMinhDuy10-Oct-07 22:37

PhanMinhDuy

10-Oct-07 22:37

I want to use this function to get close event from WORD(like DoModal() in Dialog). My code like this:

---------------------------------------------------------------------------------------------
COleDispatchDriver DocProperties(pDispatch, FALSE);
_variant_t Property((long)Word::wdPropertyPages);
_variant_t Result;

DocProperties.InvokeHelper(DISPID_....,
DISPATCH_...,
VT_BSTRT,
(void*)&Result,
(BYTE*)VTS_VARIANT,
&Property);
---------------------------------------------------------------------------------------------
Is it correct idea? And what I have to input for 3 first parameters? Thank you.

[SOLVED]type specifier for UINT64

chandu00410-Oct-07 22:36