Incompatible behavior -O0, -O3, std::cout

[Pankaj Gupta]

Hello Everyone

I noticed some thing strange recently. This code (under g++ (GCC) 3.2.3 
20030502 (Red Hat Linux 3.2.3-53)), provides this output with -O0 flag:
-f2() called
-f1() called-
12
And with -O3 flag:
-f1() called-
-f2() called
12

Here's the code:

#include <cstdio>
#include <iostream>


int f1() {
  fprintf(stderr, "-f1() called-\n");
  return 1;
}


int f2() {
  fprintf(stderr, "-f2() called\n");
  return 2;
}

int main(int argc, char **argv) {
 std::cout << f1() << f2() << std::endl;
}


I'm pretty sure that I am depending on an undefined behavior here, but 
maybe you guys would want to have a deeper look at this.


Also, if this is not very off-topic, could some one please tell me whether 
the << operators for std::ostream are members of the class, or are global 
functions (operators).

I think, if are global, it would be same as depending upon the order of 
evaluation of arguments to a function (which would be wrong according to 
the C++ standard), but if they were members of the stream classes, then it 
would evaluate to a().b().c().d() and we should expect f1() to be called 
before f2(). - Is that correct?


Thanks and Best Regards
Pankaj


--



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 Pankaj Gupta
 Infrastructure Team   -   Tower Research Capital

 Phone: 212-219-6012 [Work]
        551-358-0684 [Cell]

 Mail:  [EMAIL PROTECTED]
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