朱莉娅有三元条件运算符吗? [英] Does Julia have a ternary conditional operator?

问题描述

Python，Java和Scala具有三元运算符.朱莉娅相当于什么?

Python, Java and Scala have ternary operators. What is the equivalent in Julia?

推荐答案

对于内联使用，一个? b:c存在，如前一个答案所述.但是，值得注意的是，Julia中的if-else-end在大多数Lisp方言中的工作方式与if if cond expr1 expr2一样，既充当if子句又充当三元运算符.这样，if-then-else返回执行的表达式的返回值.

For inline use, a ? b : c exists, as mentioned by the previous answer. However it is worth noting that if-else-end in Julia works just like (if cond expr1 expr2) in most Lisp dialects which acts both as the if-clause and as the ternary operator. As such, if-then-else returns the return value of the expression that gets executed.

意思是你可以写类似的东西

Meaning that you can write things like

function abs(x)
    if x > 0
        x
    else
        -x
    end
end

，这将返回您想要的内容.您不必使用return语句来中断功能块，只需返回if块返回的值即可.

and this will return what you want. You do not have to use a return statement to break the function block, you just return the value returned by the if-block.

内联，您可以编写

if (x > 0) x else -x end 

将返回与三元运算符表达式(x> 0)相同的东西吗? x:-x，但具有避免使用perl-ish?:符号的好处，并且通常更具可读性.

which will return the same thing as the ternary operator expression (x > 0) ? x : -x , but has the benefit of avoiding perl-ish ?: symbols and is generally more readable.

大多数语言的三元运算符与if-then-else分开，因为if子句是语句，而在类似lisp的语言中，它们是表达式，就像其他所有子句一样，并且具有返回值.

Most languages have a ternary operator separate from if-then-else because if clauses are statements, while in lisp-like languages they are expressions just like everything else and have a return value.

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