Elixir 中字符串比较的双等号和三等号之间的区别

Question

我正在阅读一本关于 Elixir 的书：Introducing Elixir。

在字符串比较中说：

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

如果两个运算符的意思相同，那有什么用呢？

Answer 1

我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

还有 !==

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

值得注意的是，这些函数使用了以下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.

Elixir 中字符串比较的双等号和三等号之间的区别

Difference between double equals and triple equals for String Comparison in Elixir

elixir