Here is an example, where left-right associativity of function call operator matters: #include <stdio.h> void foo(void) { puts(“foo”); } void (*bar(void))(void) // bar is a function that returns a pointer to a function { puts(“bar”); return foo; } int main(void) { bar()(); return 0; } The function call: bar()(); is equivalent to: (bar())();
Operator precedence is defined in the appropriate standard. The standards for C and C++ are the One True Definition of what exactly C and C++ are. So if you look closely, the details are there. In fact, the details are in the grammar of the language. For example, take a look at the grammar production … Read more
In the presence of non-strict evaluation, right-associativity is useful. Let’s look at a very dumb example: foo :: Int -> Int foo = const 5 . (+3) . (`div` 10) Ok, what happens when this function is evaluated at 0 when . is infixr? foo 0 => (const 5 . ((+3) . (`div` 10))) 0 … Read more
In any sane language, the ternary operator is right-associative, such that you would expect your code to be interpreted like this: $a = 2; echo ($a == 1 ? ‘one’ : ($a == 2 ? ‘two’ : ($a == 3 ? ‘three’ : ($a == 4 ? ‘four’ : ‘other’)))); # prints ‘two’ However, the … Read more
Association direction, which controls the order of operators having their arguments evaluated, is not defined for the == method, same as for ===, !=, =~ and <=> methods as well (all of which have the same precedence and form a separate precedence group exclusively). Documentation Thus evaluation order in case of multiple operators from the … Read more
Change the first false by true. I know it seems stupid to have (true || true) but it proves your point. bool result = true || true && false; // –> true result = (true || true) && false; // –> false result = true || (true && false); // –> true
For operators, associativity means that when the same operator appears in a row, then which operator occurence we apply first. In the following, let Q be the operator a Q b Q c If Q is left associative, then it evaluates as (a Q b) Q c And if it is right associative, then it … Read more