What does this code print?

Question

Programming

In one of the projects I found a funny code fragment containing an error. The PVS-Studio analyzer noticed this error. But at first I didn't believe him. It seemed to me that the analyzer made a mistake and had already thought about launching the debugger. I looked a little more closely. No, it's really a mistake!

I changed the code a little and, using ICQ, sent the example to four programmers I know. And he asked me to write what the code below would print. All four gave incorrect answers at first.

I suggest you try to see if you can give the correct answer. What does this code print on the screen?

cout << (sizeof(char *) == 8) ? "64-bit" : "32-bit";

I suggest checking yourself. Write your answer, and then see other comments and the correct answer .

Answer 1

If I were asked in everyday life, I would be mistaken, but since. it’s immediately clear that here the question with a trick was answered correctly :-)

Answer 2

Read the code snippet. There was a feeling that the problem was with priorities. And so it happened.

Answer 3

Just use clang:

$ ./Debug+Asserts/bin/clang -fsyntax-only /tmp/zzz.cc
/tmp/zzz.cc:7:33: warning: operator '?:' has lower precedence than '<<'; '<<' will be evaluated first [-Wparentheses]
  cout << (sizeof(char *) == 8) ? "64-bit" : "32-bit";
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^
/tmp/zzz.cc:7:33: note: place parentheses around the '<<' expression to silence this warning
  cout << (sizeof(char *) == 8) ? "64-bit" : "32-bit";
                                ^
  (                            )
/tmp/zzz.cc:7:33: note: place parentheses around the '?:' expression to evaluate it first
  cout << (sizeof(char *) == 8) ? "64-bit" : "32-bit";
                                ^
          (                                          )
/tmp/zzz.cc:7:35: warning: expression result unused [-Wunused-value]
  cout << (sizeof(char *) == 8) ? "64-bit" : "32-bit";
                                  ^~~~~~~~
2 warnings generated.

Answer 4

I myself remember from my own experience that when using a ternary operator, the condition and actions must be enclosed in brackets, because the precedence of the ternary operator is lower than that of the rotation operator.

Answer 5

and it also looks interesting in the opposite direction when without parentheses:

true ? std::cout : std::cerr << "????";

Answer 6

Now I'm looking at Google.com/analytics that quite a lot of people went to the link to see the correct answer. Here the comments are empty. Looks like I scared everyone with articles that in C++ everything is not so simple... :-)
Don't be shy. It's funny, after all.

Answer 7

Prints the same as the equivalent: cout << (sizeof(char *) == 8). The priority of "<<" is higher than "?:".