Class Not Declared?? (C++)

Question

ISBN.cpp:8: error: 'ISBN' has not been declared

ISBN.cpp:8: error: ISO C++ forbids declaration of 'ISBN' with no type ISBN.cpp: In function 'int ISBN()':

ISBN.cpp:9: error: 'area' was not declared in this scope

ISBN.cpp:10: error: 'publisher' was not declared in this scope

ISBN.cpp:11: error: 'title' was not declared in this scope ISBN.cpp:12: error: 'checkdigit' was not declared in this scope ISBN.cpp:13: error: 'isbnStr' was not declared in this scope

Line 8 through 14 are:

ISBN::ISBN() {
 area = NULL;
 publisher = NULL;
 title = NULL;
 checkdigit = NULL;
 isbnStr = NULL;
}

They are all declared in the header:

class ISBNPrefix;
class ISBN
{
private:
 int area;
 int publisher;
 int title;
 char checkdigit;
 char* isbnStr[10];
public:
 ISBN();
...

Any ideas as to what could be the issue here? I'm guessing that its something simple I'm missing.

Could you try and get the formatting sorted out? It's really hard to follow code that's all on one line. Indent all your code by at least 4 space characters and it should all work better. — Tim Martin
– Tim Martin, Commented Mar 4, 2011 at 21:54
Blind guess: Circular header dependencies often cause this problem, as the multiple-include guards cause the second iteration round the circular header include to fail silently. — Tim Martin
– Tim Martin, Commented Mar 4, 2011 at 21:56
Are you sure you want ten character pointers? char isbnStr[10]; looks more reasonable to me... — fredoverflow
– fredoverflow, Commented Mar 4, 2011 at 22:06

dnadlinger · Accepted Answer · 2011-03-04 21:58:24Z

8

This might seem obvious, but have you double-checked that you actually include the header file in ISBN.cpp? Maybe, you have accidentally used the same preprocessor constant as include guard for two headers, causing the file with the declaration of ISBN to be effectively ignored? The snippets you posted look fine to me…

answered Mar 4, 2011 at 21:58

dnadlinger

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1 Comment

Tony Over a year ago

+1 for "accidentally used the same preprocessor constant" the number of times I have seen that.

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