什么是:= 运算符? [英] What is the := operator?

问题描述

在某些编程语言中，我看到(例如):

In some programming languages, I see (ex.):

x := y

这个 := 运算符通常被称为什么?它有什么作用?

What is this := operator generally called and what does it do?

推荐答案

在所有支持运算符 := 的语言中，它意味着赋值.

In all languages that support an operator := it means assignment.

• 在支持运算符 := 的语言中，= 运算符通常表示相等比较.
• 在 = 表示赋值的语言中，== 通常用于相等比较.

• In languages that support an operator :=, the = operator usually means an equality comparison.
• In languages where = means assignment, == is typically used for equality comparison.

:= 是指 = 吗?

我不记得有任何语言 := 与 = 的含义相同.

I can't recall any languages where := means the same as =.

在 MySQL 中 := 和 = 都用于 assignment，但是它们不能互换，选择正确的取决于上下文.为了使事情更加混乱，= 运算符也用于 比较.将 = 解释为赋值或比较也取决于上下文.

In MySQL := and = are both used for assignment, however they are not interchangeable and selecting the correct one depends on the context. To make matters more confusing the = operator is also used for comparison. The interpretation of = as either assignment or comparison also depends on context.

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