conditional-operator

Nullable type issue with ?: Conditional Operator

由 混江龙づ霸主 提交于 2019-11-26 10:18:50
Could someone explain why this works in C#.NET 2.0: Nullable<DateTime> foo; if (true) foo = null; else foo = new DateTime(0); ...but this doesn't: Nullable<DateTime> foo; foo = true ? null : new DateTime(0); The latter form gives me an compile error "Type of conditional expression cannot be determined because there is no implicit conversion between '<null>' and 'System.DateTime'." Not that I can't use the former, but the second style is more consistent with the rest of my code. This question has been asked a bunch of times already. The compiler is telling you that it doesn't know how convert

What is the idiomatic Go equivalent of C&#39;s ternary operator?

由 大城市里の小女人 提交于 2019-11-26 10:14:54
问题 In C/C++ (and many languages of that family), a common idiom to declare and initialize a variable depending on a condition uses the ternary conditional operator : int index = val > 0 ? val : -val Go doesn\'t have the conditional operator. What is the most idiomatic way to implement the same piece of code as above ? I came to the following solution, but it seems quite verbose var index int if val > 0 { index = val } else { index = -val } Is there something better ? 回答1: As pointed out (and

What is a Question Mark “?” and Colon “:” Operator Used for? [duplicate]

由 主宰稳场 提交于 2019-11-26 10:12:57
This question already has an answer here: What is the Java ?: operator called and what does it do? 16 answers Two questions about using a question mark "?" and colon ":" operator within the parentheses of a print function: What do they do? Also, does anyone know the standard term for them or where I can find more information on their use? I've read that they are similar to an 'if' 'else' statement. int row = 10; int column; while (row >= 1) { column = 1; while(column <= 10) { System.out.print(row % 2 == 1 ? "<" : "\r>"); ++column; } --row; System.out.println(); } Brendan Long This is the

JavaScript if alternative [duplicate]

由 家住魔仙堡 提交于 2019-11-26 09:58:55
问题 This question already has an answer here: Question mark and colon in JavaScript 7 answers What does this bit of code represent? I know it\'s some kind of if alternative syntax... pattern.Gotoccurance.score != null ? pattern.Gotoccurance.score : \'0\' Update: What\'s the need for this sort of coding? Is this more efficient or just a shortened version with the same efficiency? 回答1: It is the conditional operator, it is equivalent to something like this: if (pattern.Gotoccurance.score != null) {

C# conditional AND (&&) OR (||) precedence

由 守給你的承諾、 提交于 2019-11-26 09:29:32
问题 We get into unnecessary coding arguments at my work all-the-time. Today I asked if conditional AND (&&) or OR (||) had higher precedence. One of my coworkers insisted that they had the same precedence, I had doubts, so I looked it up. According to MSDN AND (&&) has higher precedence than OR (||). But, can you prove it to a skeptical coworker? http://msdn.microsoft.com/en-us/library/aa691323(VS.71).aspx bool result = false || true && false; // --> false // is the same result as bool result =

CSS “and” and “or”

由 核能气质少年 提交于 2019-11-26 06:37:34
问题 I\'ve got quite big trouble, because i need to anathematise from styling some input types. I had something like: .registration_form_right input:not([type=\"radio\") { //Nah. } But i don\'t want to style checkboxes too. I\'ve tried: .registration_form_right input:not([type=\"radio\" && type=\"checkbox\"]) .registration_form_right input:not([type=\"radio\" && \"checkbox\"]) .registration_form_right input:not([type=\"radio\") && .registration_form_right input:not(type=\"checkbox\"]) How to use &

Ternary operator (?:) in Bash

由 心已入冬 提交于 2019-11-26 06:11:12
问题 Is there a way to do something like this int a = (b == 5) ? c : d; using Bash? 回答1: ternary operator ? : is just short form of if/else case "$b" in 5) a=$c ;; *) a=$d ;; esac Or [[ $b = 5 ]] && a="$c" || a="$d" 回答2: Code: a=$([ "$b" == 5 ] && echo "$c" || echo "$d") 回答3: If the condition is merely checking if a variable is set, there's even a shorter form: a=${VAR:-20} will assign to a the value of VAR if VAR is set, otherwise it will assign it the default value 20 -- this can also be a

How can I assign a Func<> conditionally between lambdas using the conditional ternary operator?

由 好久不见. 提交于 2019-11-26 05:31:07
问题 Generally, when using the conditional operator, here\'s the syntax: int x = 6; int y = x == 6 ? 5 : 9; Nothing fancy, pretty straight forward. Now, let\'s try to use this when assigning a Lambda to a Func type. Let me explain: Func<Order, bool> predicate = id == null ? p => p.EmployeeID == null : p => p.EmployeeID == id; That\'s the same syntax, and should work? Right? For some reason that doesn\'t. The compiler gives this nice cryptic message: Error 1 Type of conditional expression cannot be

What is ?: in PHP 5.3? [duplicate]

由 老子叫甜甜 提交于 2019-11-26 04:41:45
问题 This question already has answers here : Closed 9 years ago . Possible Duplicate: What are the PHP operators “?” and “:” called and what do they do? From http://twitto.org/ <?PHP require __DIR__.\'/c.php\'; if (!is_callable($c = @$_GET[\'c\'] ?: function() { echo \'Woah!\'; })) throw new Exception(\'Error\'); $c(); ?> Twitto uses several new features available as of PHP 5.3: The DIR constant The ?: operator Anonymous functions What does number 2 do with the ?: in PHP 5.3? Also, what do they

How to write an inline IF statement in JavaScript?

由 六月ゝ 毕业季﹏ 提交于 2019-11-26 04:34:53
问题 How can I use an inline if statement in JavaScript? Is there an inline else statement too? Something like this: var a = 2; var b = 3; if(a < b) { // do something } 回答1: You don't necessarily need jQuery. JavaScript alone will do this. var a = 2; var b = 3; var c = ((a < b) ? 'minor' : 'major'); The c variable will be minor if the value is true , and major if the value is false . This is known as a Conditional (ternary) Operator. https://developer.mozilla.org/en-US/docs/JavaScript/Reference
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