|= 在 C++ 中是什么意思
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What does |= means in c++
提问by vico
I have code line
我有代码行
int i =0;
result |= EXPECT_EQUAL(list.size(), 3);
What does |=mens?
什么是|=男士？
I was trying to compile something like:
我试图编译类似的东西：
int result |= 5;
but got error:
但有错误：
aaa.cpp:26:16: error: expected initializer before ‘|=' token
回答by Serge Ballesta
a |= b;is just syntactic sugar for a = a | b;. Same syntax is valid for almost every operator in C++.
a |= b;只是a = a | b;. 相同的语法对 C++ 中的几乎所有运算符都有效。
But int i |= 5;is an error, because in the definition line you must have an initialisation, that is an expression that does not use the variable being declared.
但这int i |= 5;是一个错误，因为在定义行中您必须有一个初始化，即一个不使用被声明的变量的表达式。
int i=3;
i |= 5;
is valid and will give value 7 (3 | 5) to i.
是有效的，并且会给 7 (3 | 5) 值i。
回答by Christian Hackl
It's the operator for assignment by bitwise OR.
它是按位 OR 赋值的运算符。
http://en.cppreference.com/w/cpp/language/operator_assignment
http://en.cppreference.com/w/cpp/language/operator_assignment
int result |= 5;
int result |= 5;
You cannot initialize an intand assign something to it at the same time. Initialization and assignment are different things. You'd have to write:
您不能同时初始化一个int并为其分配一些东西。初始化和赋值是不同的事情。你必须写：
int result = 0;
result |= 5;
If this is what you intend, of course. Since int result |= 5;is not C++, we can only guess about your intention.
当然，如果这是您的意图。由于int result |= 5;不是C++，我们只能猜测你的意图。
