How can I assign a string to a Uint8 variable?

Question

1.00/5 (1 vote)

See more:

I am trying to assign a string to a Uint8 variable, it didn't work to typecast or anything like that so what I tried to do first was to assign via a file so that I would first write the string to stderr.txt and then use fscanf to read the string. I used fscanf because you can choose what type to read with and so then I would have successfully converted the string to Uint8, right? Wrong! I then found out that the program doesn't write normal characters during execution so that if the string contained for example "Test", then the Uint8 would contain something like "(!µ@" because the file didn't contain normal characters during execution.
Now my question is simply this: how do I assign a string to a Uint8 variable so that if the string contains "Test", then the Uint8 variable will conatin "Test"?(but in a diffrent format of course)
So i would like to use it like this:
Uint8 data;
string str;
data = str;

*do whatever*

Posted 24-Sep-11 9:04am

Karsten Malmquist

Updated 24-Sep-11 23:42pm

v2

Add a Solution

Comments

Philippe Mori 24-Sep-11 16:50pm

Well, your question is not clear... and does not make any sense.

First, it is tagged as C++/CLI but it seems you are using C++ types and not .NET types (System::String and System::Byte).

Then Uint8 as spelled come from where?

Does your string type is std::string from the C++ librairies or the .NET type for C# string (that is System::String)?

Also by assing, do you mean some kind of cast of a conversion to a numeric type or the value of the first characters.

Finaly, your code sample it not clear. Does the string is a textual number? Something like string str = "23" and you would want data to have a value of 23?

Also since normally Uint8 is a typedef for a single character, then your string "(!µ@" is not really possible.

Also if your string str contains "Test" what do you expect Uint8 to contains.

And how can you have "(!µ@" when the code is not even supposed to compile!

Karsten Malmquist 24-Sep-11 17:42pm

My question was poorly written; I am using C++, not .NET. My question was how to get the contents of a std::string and put it into a UDP packet (I am making a server application), the UDP packet has a member called "data", but it was kind of hard to explain how the Uint8 variable was declared since I can't find the code of the structure that the variable is a member of. I would imagine that the variable is an array since you can fit multiple characters in it, but the fact that there is no indexing used also kind of eliminates that.
Also, with "(!µ@" I meant that when you write to a file using the fprintf function, then it writes some stuff that is not normal characters to the file during execution, and when you used the fscanf function to read the text from the file, then it read those weird characters so that it could for example read "(!µ@".

Philippe Mori 24-Sep-11 21:46pm

Well, find the declaration of the UDP structure and also show us the actual code fprintf and fscanf. By the way, if you want to ouptup a std::string with fprintf, you have to call member function c_str() since fprintf is declared with ... as it allows variable arguments.

Sergey Alexandrovich Kryukov 25-Sep-11 2:48am

If you use C++/CLI, you certainly use .NET (or Mono, or other CLR framework).
You have no idea what are you asking about. Not knowing either the language you use or the platform is the shame, and you certainly don't know at least one of them.
--SA

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

André Kraak · Answer 1 · 2011-09-24T09:19:00

Solution 1

From MSDN[^]:

UINT8
An 8-bit unsigned integer (range: 0 through 255 decimal). Because a UINT8 is unsigned, its first bit (Most Significant Bit (MSB)) is not reserved for signing.

This type is declared in BaseTsd.h as follows:

C++
typedef unsigned char UINT8;

So you cannot assign a string to an UINT8 variable. You can however assign a char to an UINT8 variable.

Posted 24-Sep-11 9:19am

André Kraak

Comments

Sergey Alexandrovich Kryukov 25-Sep-11 2:46am

My 5, but the answer is too long. One word would suffice: "gibberish". :-)
--SA

Albert Holguin 25-Sep-11 17:15pm

See Richard's answer, think that's what the OP meant...

Richard MacCutchan · Answer 2 · 2011-09-24T22:16:00

Solution 2

C++

Uint8* pdata;
string str;
pData = new Uint8[str.length() + 1];
memcpy (pdata, str.c_str(), str.length() + 1);

Remember you cannot cast from one type to another in the way you tried; a string and a Uint8 are not in any way compatible.

Posted 24-Sep-11 22:16pm

Richard MacCutchan

Updated 25-Sep-11 2:29am

v2

Comments

Albert Holguin 25-Sep-11 17:14pm

This does exactly what he needs (after reading the UDP info he posted above). +5

Richard MacCutchan 26-Sep-11 4:51am

Thanks; it still amazes me that someone can be writing a UDP server application and yet still does not understand that casting a string to a Uint8 will not work.