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Showing posts from July, 2008

return void

I thought it would be interesting to discuss a subtle C/C++ interview question I learned recently. Question is deceptively simple: "Can you write a return statement in a function that returns void?" The answer is "Yes! You can return void!" The following program seems to be a valid C/C++ program. static void foo (void) { } static void bar (void) { return foo(); // Note this return statement. } int main (void) { bar(); return 0; } I tested it using gcc4 and VS9. With -ansi and -pedantic compiler options for gcc, it throws just a warning pointing at line #5. return_void.c:5: warning: return with a value, in function returning void Although use of such a feature is not clear in a C program, it is particularly useful while using templates. Consider, template <class T> T FOO (void) { return T(); // Default construction } template <class T> T BAR (void) { return FOO<T>(); // Syntactic consistency. Same for int, void and everything else. } int m