You cannot use the default equality operator in an overloaded implementation of the equality operator.

不能在相等运算符的重载实现中使用默认相等运算符。

youdao

So this is the equality operator, whereas the single equal sign is the assignment operator.

所以这是相等操作符，然而那个单等号是一个赋值运算符。

哈佛公开课 - 计算机科学课程节选

This is the equality operator.

这就是等于号。

哈佛公开课 - 计算机科学课程节选

bug Now, this was not the bug in this program because I did, in fact, use the equality operator and so it feels like if I type the word foo both times I should, in fact, get back you type the same thing.

现在，在这个程序中这个不是，因为，实际上，我使用了等于号,如果我输入单词foo两次，我返回给你“输入了相同的东西“

哈佛公开课 - 计算机科学课程节选