elixir - Elixir 中字符串比较的双重等于和三重等于之间的区别

Question

我正在读一本关于 Elixir 的书:Introducing Elixir .

在字符串比较它说:

Elixir offers two options for comparing string equality, == and === operators. The == operator is generally the simplest though the other produces the same result.

如果他们的意思相同，那么拥有两个运算符的目的是什么？

Answer 1

想到的一个例子是浮点数——它使用与字符串相同的比较函数:

iex> 1 == 1    #true
iex> 1 == 1.0  #true
iex> 1 === 1   #true
iex> 1 === 1.0 #false

对于 !==

iex> 1 != 2    #true
iex> 1 != 1.0  #false
iex> 1 !== 2   #true
iex> 1 !== 1.0 #true

值得注意的是，这些函数使用以下 Erlang 表达式:

Elixir | Erlang
==     | ==
===    | =:=
!=     | /=
!==    | =/=

来自 Erlang documentation :

When comparing an integer to a float, the term with the lesser precision is converted into the type of the other term, unless the operator is one of =:= or =/=. A float is more precise than an integer until all significant figures of the float are to the left of the decimal point. This happens when the float is larger/smaller than +/-9007199254740992.0. The conversion strategy is changed depending on the size of the float because otherwise comparison of large floats and integers would lose their transitivity.