C++ 对象实例化与赋值
这有什么区别:
TestClass t;
还有这个:
TestClass t = TestClass();
我预计第二个可能会调用构造函数两次，然后是 operator=，但它只调用了一次构造函数，就像第一个一样.
I expected that the second might call the constructor twice and then operator=, but instead it calls the constructor exactly once, just like the first.
推荐答案
TestClass t;
调用默认构造函数.
TestClass t = TestClass();
是一个复制初始化.它将调用 TestClass() 的默认构造函数，然后调用复制构造函数(理论上，复制受复制省略约束).此处不进行任何分配.
is a copy initialization. It will call the default constructor for TestClass() and then the copy constructor (theoretically, copying is subject to copy elision). No assignment takes place here.
还有直接初始化的概念:
TestClass t(TestClass());
如果你想使用赋值运算符:
If you want to use the assignment operator:
TestClass t;
TestClass s;
t = s;
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