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Message: [QUOTE="Jack Klein, post: 3479435"] You are missing the simple fact that the C standard statement is, in 6.9 p5: "An external definition is an external declaration that is also a definition of a function (other than an inline definition) or an object. If an identifier declared with external linkage is used in an expression (other than as part of the operand of a sizeof operator whose result is an integer constant), somewhere in the entire program there shall be exactly one external definition for the identifier; otherwise, there shall be no more than one." If you define an external object in more than one translation, you are violating the first "shall" clause in this paragraph. This paragraph is in a "Semantics" section, not a "Constraints" section. Violating a "shall" clause outside of a constraints section means that the program produces undefined behavior, no diagnostic is required. It just so happens that one possible consequence of undefined behavior is for the program to do what you expect and/or want it to do. How the tool set you use deals with a particular case of undefined behavior is up to the tool set, since the C standard imposes no requirements. It just so happens that some tool sets, on some platforms, use a linkage model that allows multiple external definitions, as long as none of them or only one of them, but not more than one, specify an initializer. The linker will merge duplicate external definitions into a single object. It also just so happens that there are a large number of other implementations that will reject this at the link stage, complaining of multiple definitions. Either behavior is allowed by the C standard, as is just about any other, because the behavior is undefined by the standard. -- Jack Klein Home: [URL]http://JK-Technology.Com[/URL] FAQs for comp.lang.c [URL]http://c-faq.com/[/URL] comp.lang.c++ [URL]http://www.parashift.com/c++-faq-lite/[/URL] alt.comp.lang.learn.c-c++ [URL]http://www.club.cc.cmu.edu/~ajo/docs/FAQ-acllc.html[/URL] [/QUOTE]

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