Solved

LPVOID conversion

Posted on 2007-11-18
7
6,418 Views
Last Modified: 2010-04-21
How to convert a LPVOID variable to a string ?
0
Comment
Question by:walterwkh
  • 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 500 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
Master Your Team's Linux and Cloud Stack

Come see why top tech companies like Mailchimp and Media Temple use Linux Academy to build their employee training programs.

 
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

Efficient way to get backups off site to Azure

This user guide provides instructions on how to deploy and configure both a StoneFly Scale Out NAS Enterprise Cloud Drive virtual machine and Veeam Cloud Connect in the Microsoft Azure Cloud.

Question has a verified solution.

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

Suggested Solutions

Title # Comments Views Activity
Install Problem 13 31
Hey Audio! 3 30
NEED HELP WITH VISUAL STUDIO 2017 (beginner) 6 39
How do i run a c++ file? 15 29
This article is for Object-Oriented Programming (OOP) beginners. An Interface contains declarations of events, indexers, methods and/or properties. Any class which implements the Interface should provide the concrete implementation for each Inter…
Container Orchestration platforms empower organizations to scale their apps at an exceptional rate. This is the reason numerous innovation-driven companies are moving apps to an appropriated datacenter wide platform that empowers them to scale at a …
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.
The goal of this video is to provide viewers with basic examples to understand and use conditional statements in the C programming language.

810 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