should std::common_type use std::decay? Yes, see Library Working Group Defect #2141. Short version (long version, see link above): declval<A>() returns a A&& common_type is specified via declval, n3337: template <class T, class U> struct common_type<T, U> { typedef decltype(true ? declval<T>() : declval<U>()) type; }; common_type<int, int>::type therefore yields int&&, which is unexpected proposed resolution … Read more
$a = array(‘a’ => ‘abc’) + ($condition ? array(‘b’ => ‘xyz’) : array());
In Kotlin, if statements are expressions. So the following code is equivalent: if (a) b else c The distinction between expression and statement is important here. In Java/C#/JavaScript, if forms a statement, meaning that it does not resolve to a value. More concretely, you can’t assign it to a variable. // Valid Kotlin, but invalid … Read more
This doesn’t work because the compiler will not insert an implicit conversion on both sides at once, and null requires an implicit conversion to become a nullable type. Instead, you can write task.ActualEndDate = TextBoxActualEndDate.Text != “” ? DateTime.Parse(TextBoxActualEndDate.Text) : new DateTime?(); This only requires one implicit conversion (DateTime to DateTime?). Alternatively, you can cast … Read more
Rust does not have the ternary operator because it’s not needed. Almost everything evaluates to some value, and if / else expressions are no exception: let r = 42.42; let sgn_r = if r >= 0. { 1. } else { -1. }; You’ll note that I’ve also changed your variable names to be idiomatic … Read more
value = if maxValue > minValue then minValue else maxValue
Boolean expressions in most programming languages don’t follow the same grammar rules as English. You have to do separate comparisons with each string, and connect them with or: if x == “monkey” or x == “monkeys”: print “You’re right, they are awesome!!” else: print “I’m sorry, you’re incorrect.”, x[0].upper() + x[1:], “is not the right … Read more
Very odd, perhaps .NET optimization is backfireing in your case: The author disassembled several versions of ternary expressions and found that they are identical to if-statements, with one small difference. The ternary statement sometimes produces code that tests the opposite condition that you would expect, as in it tests that the subexpression is false instead … Read more
From http://en.wikipedia.org/wiki/%3F%3A A GNU extension to C allows omitting the second operand, and using implicitly the first operand as the second also: a = x ? : y; The expression is equivalent to a = x ? x : y; except that if x is an expression, it is evaluated only once. The difference is … Read more
I prefer to think of it as “bitwise vs. conditional” rather than “logical vs conditional” since the general concept of “logical” applies in both cases. x & y // bitwise AND, 0101 & 0011 = 0001 x | y // bitwise OR, 0101 | 0011 = 0111 x && y // true if both x … Read more