Want to win a PS4? Go Premium and enter to win our High-Tech Treats giveaway. Enter to Win

x
?
Solved

LPVOID conversion

Posted on 2007-11-18
7
Medium Priority
?
6,778 Views
Last Modified: 2010-04-21
How to convert a LPVOID variable to a string ?
0
Comment
Question by:walterwkh
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
  • 2
7 Comments
 
LVL 40

Expert Comment

by:evilrix
ID: 20307321
Examples...
// STL string
void foo(LPVOID lpVoid)
{
    // C++
    std::string *pString = reinterpret_cast<std::string *>(lpVoid);
    // C
    std::string *pString = (std::string *) lpVoid;
}
 
// C-String void foo(LPVOID lpVoid)
{
    // C++
    char *pString = reinterpret_cast<char *>(lpVoid);
 
    // C
    char *pString = (char *) lpVoid;
}

Open in new window

0
 
LVL 40

Accepted Solution

by:
evilrix earned 2000 total points
ID: 20307326
>> // C-String void foo(LPVOID lpVoid)

Typo; should be...

// C-String

void foo(LPVOID lpVoid)

// STL string
 
void foo(LPVOID lpVoid)
{
    // C++
    std::string *pString = reinterpret_cast<std::string *>(lpVoid);
    // C
    std::string *pString = (std::string *) lpVoid;
}
 
// C-String
 
void foo(LPVOID lpVoid)
{
    // C++
    char *pString = reinterpret_cast<char *>(lpVoid);
 
    // C
    char *pString = (char *) lpVoid;
}

Open in new window

0
 
LVL 40

Expert Comment

by:evilrix
ID: 20307334
In C++ you should use reinterpret_cast<>() as it is safer than C-style casting.
http://msdn2.microsoft.com/en-us/library/e0w9f63b(VS.80).aspx

Note, then you convert to a pointer of a different type the only safe thing you can do with that pointer is convert it back! Anything else is, at best, non-portable.

All styles of casting are discussed here...
http://msdn2.microsoft.com/en-us/library/x9wzb5es(VS.80).aspx

I hope this help.

-Rx.
0
What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.

 
LVL 15

Expert Comment

by:efn
ID: 20309221
It depends on what the LPVOID addresses and what kind of string you mean.

If the LPVOID points to some kind of string, you can convert it to a pointer to that kind of string with a cast, as evilrix showed.  A static-cast will work as well as a reinterpret-cast.  If you want a different kind of string, you will have to construct a new string from what the pointer addresses.  This will also require a cast to turn the LPVOID into something you can use.

For example, if the LPVOID points to a C-style null-terminated string and you want a std::string, you can do this:

std::string exvoid(<static-cast>(const char *) lpVoid);
0
 

Author Closing Comment

by:walterwkh
ID: 31409791
thanks both evilrix and efn
0
 
LVL 40

Expert Comment

by:evilrix
ID: 20310784
>> std::string exvoid(<static-cast>(const char *) lpVoid);
std::string exvoid(static_cast<const char *>(lpVoid));
0
 
LVL 15

Expert Comment

by:efn
ID: 20311025
Right, thanks.
0

Featured Post

Free Tool: Site Down Detector

Helpful to verify reports of your own downtime, or to double check a downed website you are trying to access.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Article by: SunnyDark
This article's goal is to present you with an easy to use XML wrapper for C++ and also present some interesting techniques that you might use with MS C++. The reason I built this class is to ease the pain of using XML files with C++, since there is…
Performance in games development is paramount: every microsecond counts to be able to do everything in less than 33ms (aiming at 16ms). C# foreach statement is one of the worst performance killers, and here I explain why.
The goal of this video is to provide viewers with basic examples to understand opening and writing to files in the C programming language.
The goal of this video is to provide viewers with basic examples to understand how to create, access, and change arrays in the C programming language.

636 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question