Why does (0 < 5 < 2) result true in C++?

Question

The following code std::cout << (0 < 5 < 2); outputs 1 (true) to the console, even though mathematically speaking, 5 < 2 is false. What is the logic behind this?

Hypothesis: This is because 0 < 5 is calculated as 1, therefore 0 < 5 < 2 is calculated as 1 < 2. Am I correct?

Correct. It is evaluated left to right. Use parentheses for separate evaluation — Beshambher Chaukhwan, Feb 23 '21 at 16:14
I didn't know `bool` to `int` counted as an integer promotion that could be part of the [usual arithmetic conversions](https://en.cppreference.com/w/c/language/conversion). Does a `bool` primitive count as a bitfield of type _Bool? — Nathan Pierson, Feb 23 '21 at 16:19
`0 < 5` evaluates to `true`, as does `true < 2`. `std::cout << true` writes "1" unless the flag `std::ios_base::boolalpha` is set on `std::cout` — Caleth, Feb 23 '21 at 16:41

score 0 · Answer 1 · answered Feb 23 '21 at 16:16

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You have answered the question yourself, you are 100% correct. Evaluation is done on the basis of precedence. Might help you:-C++ operators Precedence

answered Feb 23 '21 at 16:16

Abhishek Dutt

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Precedence and ORDER in the case of ties. – user4581301 Feb 23 '21 at 16:19

Why does (0 < 5 < 2) result true in C++?

1 Answers1