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Dark GDK / Strings (newbie question)

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Michael P
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Posted: 17th Jan 2008 20:43
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I have 2 string related questions:

1. What is the best way to deal with strings considering that I need to be able to add several strings together?

At the moment I'm doing the following whenever I want to use the dbPrint command:


Is that a good way of doing it, or is there a better/simpler way of doing it?

2. How do I convert integers into standard strings?
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tempicek
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Posted: 17th Jan 2008 23:01
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One way is to use more powerful string library, like ATLString for example:



You can do much more things and easily with this class.

Converting anything to string is possible using a method of the CAtlString or using a standard function:




See documentation for both both the function and the class. Also, you can use GDK function dbStr which converts integer to a string.
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SynReaper
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Posted: 17th Jan 2008 23:18
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The GDK has a built-in function for handling the conversion which is much faster to code:

SomeStringVar = dbStr ( iValue );

I have not thoroughly tested this function yet, but it will definitely return a string from an integer iValue.


-- 010100110111100101101110010100100110010101100001011100000110010101110010
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Michael P
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Posted: 18th Jan 2008 08:42
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Quote: "One way is to use more powerful string library, like ATLString"


Where can I get my hands on this library - I had a quick google and couldn't find a download link for it.
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tempicek
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Posted: 18th Jan 2008 09:14
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Quote: "Where can I get my hands on this library - I had a quick google and couldn't find a download link for it."


It should be integral part of Visual Studio, so you basically only need to add the #include <atlstr.h> to your source code and then open project properties and in General tab set "Use of ATL" to "Using ATL in Static Library".

Unfortunately, I'm not sure if you have ATL since I checked my version of VC++ (VC++2008 Express edition) and it does not contain it, so probably you need full Visual Studio Express or VS Pro (I always use full installation of Pro version where it is)? Not sure, so try to check that out; if it's there, you would find a folder "atlmfc" in VSInstallDir\VC\
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Michael P
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Posted: 18th Jan 2008 13:41 Edited at: 18th Jan 2008 13:46
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I think I need VS Pro, and that costs a fair bit I'll be sticking to standard strings then for now

However, I have discovered a much simpler way of converting strings to char.. simply using the .copy function:

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tparkin
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Posted: 18th Jan 2008 14:50 Edited at: 18th Jan 2008 14:52
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Hi,

The STL string class is just as powerful as the ATL string class. The STL string class (like all other STL classes) is integrated into all versions of Visual Studio.

It looks like you're already using it, but for those reading this thread who aren't:



For more information please visit:
http://www.sgi.com/tech/stl/basic_string.html
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tempicek
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Posted: 18th Jan 2008 15:20
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Quote: "The STL string class is just as powerful as the ATL string class."


Powerful - yes. Easy to use - no. That's why I suggested ATL string, but I didn't know it's not in the Express version.
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Benjamin
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Posted: 18th Jan 2008 15:51
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Quote: "However, I have discovered a much simpler way of converting strings to char.. simply using the .copy function"

And wouldn't it be simpler still to just use the c_str() member of the string class as before?

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tempicek
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Posted: 18th Jan 2008 16:15
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Quote: "And wouldn't it be simpler still to just use the c_str() member of the string class as before?"


c_str() returns constant pointer, but functions like dbPrint expects non-constant pointer, so it can't be used directly (which is awful) .. it's not a problem of STL string class, that's again an amazing primitiveness of the GDK code :/
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Benjamin
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Posted: 18th Jan 2008 16:22
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Quote: "c_str() returns constant pointer, but functions like dbPrint expects non-constant pointer, so it can't be used directly (which is awful)"

Then typecast it:



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Pixel Perfect
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Posted: 18th Jan 2008 16:24
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Exactly, that's all it needs. That's the beauty of C

No matter how good your code is, someone will improve on it
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tempicek
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Posted: 18th Jan 2008 16:41
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Right, I can not argue in that, but it's not generally a good idea/habit to typecasting and pasting const pointers to a non-cost argument of a function which can potentially change it. (Sure, we can suppose that Print function won't change a string, still...)
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Pixel Perfect
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Posted: 18th Jan 2008 16:59
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Agreed, casting always has to be used with caution. But it's a powerful tool when used sensibly, and the benefit of using String classes over the standard C string handling has got to be worth it, especially where beginners are concerned as it avoids one of the greatest bug inducing areas for the un-initiated!

No matter how good your code is, someone will improve on it
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Michael P
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Posted: 18th Jan 2008 17:12 Edited at: 18th Jan 2008 17:12
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Quote: "dbPrint((char*) myString.c_str());"


Damn, I wish I'd known how to do that before Note to self: read typecasting tutorial.
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Benjamin
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Posted: 18th Jan 2008 18:12 Edited at: 18th Jan 2008 18:20
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Quote: "Right, I can not argue in that, but it's not generally a good idea/habit to typecasting and pasting const pointers to a non-cost argument of a function which can potentially change it."

Then call it bad practice that dbPrint doesn't take a const pointer.

Besides, regardless of const-ness, a function should not modify an input buffer unless it is documented that it does so. If it needs to modify it for its own internal use, it should make its own copy of it first.

At least, in my experience.

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tempicek
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Posted: 18th Jan 2008 20:06
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Quote: "Then call it bad practice that dbPrint doesn't take a const pointer."


That I stated before. There's a lot of uglyness in GDK

Quote: "Besides, regardless of const-ness, a function should not modify an input buffer unless it is documented that it does so. If it needs to modify it for its own internal use, it should make its own copy of it first."


True, indeed. On the other side - GDK docs lacks info.
Still you can pretty much assume what a function "SetPosition( const CVector * )" does without reading doc, but for a "SetPosition( CVector * )" I'm always unsure...
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