Compiler error for s.clear()

[MrDoomMaster]

Consider the following code:

string dup(char c, int n) {
    string s;
    s.clear();
    s.insert(s.begin(), n, c);
    return s; }

My compiler is: Microsoft Visual C++ 6.0

The compiler error I receive is:
h:\c++\proj12ateame\basicutils.h(32) : error C2039: 'clear' : is not a member of 'basic_string<char,struct std::char_traits<char>,class std::allocator<char> >'

This code works FINE on Microsoft Visual Studio .NET 2003, yet it doesn't on Visual C++ 6.0? If someone could explain to me what's going on, I would be grateful.

The header files I have included with this code are <string> and <math.h>

Thanks again guys. You're very helpful.

[AvDav]

std::string dup(char c, int n)
{
	return std::string(n, c);
}

[Gabriel Fleseriu]

1. clear() doesn't seem to be a member of std::basic_string, does it?
2. you don't need something like clear() there, as the string is empty.

[AvDav]

However it is strange, I have SGI-STL docs, there is a clear() member in their implementation...

[Gabriel Fleseriu]

Originally posted by AvDav
However it is strange, I have SGI-STL docs, there is a clear() member in their implementation...

I didn't see it in the Dinkumware implementation, nor did I find it in the C++ Standard...

[Yves M]

Yes, it's not in the standard, but STLPort includes it. I'm wondering why it isn't in the standard though, since it's potentially a useful function.

[Philip Nicoletti]

Actually, clear() is in the standard ( 21.3.3 , para 12)

With the "effects: behaves as if the function calls"

erase( begin() , end() );

[Yves M]

Interesting, that's true. The thing is that it's not listed in the public interface for basic_string nor in the index, which is a bit strange. Maybe this is already addressed in a defect report somewhere.

[MrDoomMaster]

I noticed some people specified Std:: in front of it, but this isn't needed in my case because at the top of the header file that contains this function I used namspace STD.

I hope someone can help me resolve this issue. I haven't really been able to understand the discussion above, about the SGI-STL and Dinkumware lol

Thanks again.

[Yves M]

AvDav gave you the solution already and the rest of the discussion is about the error you get when calling std::string::clear, which doesn't seem to exist in your STL implementation.

[Assmaster]

Originally posted by MrDoomMaster (bold added by me)
I noticed some people specified Std:: in front of it, but this isn't needed in my case because at the top of the header file that contains this function I used namspace STD.

You shouldn't put "using namespace whatever;" in any header file. Doing that will result in that namespace being used by all files that include your header. Something that in turn can result in name conflicts, since the user of the header doesn't know that the namespace is used.

If you don't want to write std:: for every function/container/etc you use, put all your code in the cpp file (except the declarations of course), and put using namespace at the top of that instead.