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In-class constant
I put the title into the search engine and it turned up very little. Ok so I only looked at the first page but I'm tired.
Here's the class - don't ask what it does because I don't know, I'm just fiddling with some hashing (thanks to Prelude for the tut. on her site):
Code:
template <class T> class database {
public:
database (int max_index_data);
~database ();
private:
const int MAX_INDEX_DATA;
unsigned index[MAX_INDEX_DATA];
T data[MAX_INDEX_DATA];
};
template <class T> database<T>::database (int max_index_data)
:MAX_INDEX_DATA(max_index_data)
{
}
template <class T> database<T>::~database ()
{
}
Here are the errors which disgraced my output window
Code:
------ Build started: Project: database_bollocks, Configuration: Debug Win32 ------
Compiling...
database_bollocks.cpp
c:\Documents and Settings\lee\Desktop\database_bollocks\database_bollocks.cpp(14) : error C2327: 'database<T>::MAX_INDEX_DATA' : is not a type name, static, or enumerator
c:\Documents and Settings\lee\Desktop\database_bollocks\database_bollocks.cpp(16) : see reference to class template instantiation 'database<T>' being compiled
c:\Documents and Settings\lee\Desktop\database_bollocks\database_bollocks.cpp(14) : error C2065: 'MAX_INDEX_DATA' : undeclared identifier
c:\Documents and Settings\lee\Desktop\database_bollocks\database_bollocks.cpp(15) : error C2327: 'database<T>::MAX_INDEX_DATA' : is not a type name, static, or enumerator
c:\Documents and Settings\lee\Desktop\database_bollocks\database_bollocks.cpp(15) : error C3861: 'MAX_INDEX_DATA': identifier not found, even with argument-dependent lookup
Build Time 0:00
Build log was saved at "file://c:\Documents and Settings\lee\Desktop\database_bollocks\Debug\BuildLog.htm"
database_bollocks - 4 error(s), 0 warning(s)
---------------------- Done ----------------------
Build: 0 succeeded, 1 failed, 0 skipped
Sorry for the slightly profane project name.
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I think MAX_INDEX_DATA needs to be static or else you need to use dynamic allocation.
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The size of the object must be known at compile time, and it must be constant across all objects. But by using a per-object constant for the size of the embedded array, you'd have objects of different size. That's obviously not possible. JaWiB is right: either make the constant static and thus the same across all instances, or allocate dynamically.
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