Solved

converting a std::string to BYTE[16]

Posted on 2004-04-10
10
560 Views
Last Modified: 2008-02-01
hi,
i need some help in convert a std::string to BYTE[16]. does anyone have any idea on how to do so? thanks!

-ashrobo
0
Comment
Question by:ashrobo
10 Comments
 
LVL 8

Assisted Solution

by:mnashadka
mnashadka earned 25 total points
ID: 10797567
If you need to create a new variable, you can cast the BYTE array to a char * and use strncpy to get the value:
  BYTE bytes[16] = {0};
  std::string str = "hello";
  // Copy up to 16 characters into bytes
  strncpy((char *)bytes, str.c_str(), 16); // You could also use reinterpret_cast here

If you need to just use an existing variable in a function call, you can cast the string.c_str() to a BYTE *, but this could be an issue if the size is wrong:
myfunc((BYTE *)str.c_str()); // You could also use reinterpret_cast here

Hope this helps.
0
 
LVL 30

Expert Comment

by:Axter
ID: 10797586
>>myfunc((BYTE *)str.c_str());
FYI:
This method would be unsafe, since you're removing the constantness from the pointer.
Recommend putting the constant into the cast:
myfunc((const BYTE *)str.c_str());
0
 
LVL 86

Assisted Solution

by:jkr
jkr earned 25 total points
ID: 10797591
BYTE b[16];
string s = "12345678";
unsigned int unLen = s.size();
memset ( b, 0, sizeof(b));
memcpy ( b, s.c_str(), unLen > sizeof(b) ? sizeof(b) : unLen);
0
Active Directory Webinar

We all know we need to protect and secure our privileges, but where to start? Join Experts Exchange and ManageEngine on Tuesday, April 11, 2017 10:00 AM PDT to learn how to track and secure privileged users in Active Directory.

 
LVL 30

Accepted Solution

by:
Axter earned 75 total points
ID: 10797612
jkr,
I think you're method is safer then the code used for the previous strncpy method.
But just to add a little more efficientcy you could remove the memset, and add a nullifier after copying the string:
Example:

memcpy ( b, s.c_str(), unLen > sizeof(b) ? sizeof(b) : unLen);
b[unLen] = 0;
0
 
LVL 30

Expert Comment

by:Axter
ID: 10797619
Correction:

memcpy ( b, s.c_str(), unLen > sizeof(b) ? sizeof(b) : unLen);
if (unLen < sizeof(b)) b[unLen] = 0;
0
 
LVL 8

Expert Comment

by:mnashadka
ID: 10797834
>>Recommend putting the constant into the cast:
>>myfunc((const BYTE *)str.c_str());

Axter, I agree typically, but that depends upon whether the function takes a const or not.  I was assuming that the function took a BYTE * as a parameter, at which point putting the const there will just make you have to do a const_cast or whatever.  Even if it should be const in the function prototype, there are a lot of programmers out there who, for one reason or another (usually training), don't make the parameter const in the function.
0
 

Author Comment

by:ashrobo
ID: 11003144
i'm sorry for not replying, i haven't had the time to try the solutions provided. how can i deal with this?
0

Featured Post

Free Tool: Subnet Calculator

The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

One of a set of tools we're offering 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

What is C++ STL?: STL stands for Standard Template Library and is a part of standard C++ libraries. It contains many useful data structures (containers) and algorithms, which can spare you a lot of the time. Today we will look at the STL Vector. …
Go is an acronym of golang, is a programming language developed Google in 2007. Go is a new language that is mostly in the C family, with significant input from Pascal/Modula/Oberon family. Hence Go arisen as low-level language with fast compilation…
The goal of the tutorial is to teach the user how to use functions in C++. The video will cover how to define functions, how to call functions and how to create functions prototypes. Microsoft Visual C++ 2010 Express will be used as a text editor an…
The viewer will learn how to pass data into a function in C++. This is one step further in using functions. Instead of only printing text onto the console, the function will be able to perform calculations with argumentents given by the user.

821 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