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cannot access static member variable from static member function

Started by nlbs Oct 5, 2008 at 1:35 AM 4 replies 900+ views

Original Post

Oct 5, 2008 at 1:35 AM

Here is my Source Code.

class HtmlTagAutoCompleter{
	private:
    static stack<string> tstk;
	public:
    static bool detectStatus(const string& tagName);
};

bool HtmlTagAutoCompleter::detectStatus(const string& tagName){
	if(tstk.empty() || tstk.top() != tagName){
		tstk.push(tagName);
		return TAG_OPENED;
	}else{
		tstk.pop();
		return TAG_CLOSED;
	}
}

When I compile Compiler is firing Linker error.

../cgi++/.libs/libcgixx.so: undefined reference to `HtmlTagAutoCompleter::tstk'
collect2: ld returned 1 exit status

Whats wrong here ??

Promit

Mod

1,082

Promit

Oct 5, 2008 at 1:39 AM

You need to provide a definition for the static member in a source file somewhere -- the header file entry is only a declaration. In other words, you've told the compiler that this member exists, but not where to put it or how to initialize it. So in a source file somewhere, you need:
static stack<string> HtmlTagAutoCompleter::tstk;

Lastly, tstk is a terrible member name, and returning TAG_OPENED or TAG_CLOSED enums from a function that returns bool makes no sense.

nlbs

Author

nlbs

Oct 5, 2008 at 1:41 AM

Sorry I am not able to understand what you are saying.
Can you explain more ??

The Class signature is in a different header file and source is another .cpp file as usual

EDIT

You edited just after I Posted

nlbs

Author

nlbs

Oct 5, 2008 at 1:47 AM

Putting

stack<string> HtmlTagAutoCompleter::tstk;

in header solves However did you mean to put it in header or source??

Also which one is better put it in Header or source .cpp ??

Promit

Mod

1,082

Promit

Oct 5, 2008 at 1:48 AM

Put it in the source. If you put it in the header you'll probably end up with multiple redefinition errors.

trojanman

Oct 5, 2008 at 2:04 AM

//Headerclass HtmlTagAutoCompleter{	private:    static stack<string> tstk; //declaration	public:    static bool detectStatus(const string& tagName);};

//.cppbool HtmlTagAutoCompleter::detectStatus(const string& tagName){	if(tstk.empty() || tstk.top() != tagName){		tstk.push(tagName);		return TAG_OPENED;	}else{		tstk.pop();		return TAG_CLOSED;	}}//etc...stack<string> HtmlTagAutoCompleter::tstk; //definition

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