C++:警告:C4930:未调用原型函数(是否打算定义变量?) [英] C++: warning: C4930: prototyped function not called (was a variable definition intended?)

问题描述

我有一个没有默认构造函数的类，我创建了一个变量而没有错误地提供参数，但不是一个很好的编译器错误，而是一个链接器错误，我不能't 找到导致它的代码行.

I have a class that does not have a default constructor, I created a variable without giving parameters by mistake, but instead of a nice compiler error, I got a linker error, where I couldn't find the line of code that was causing it.

最后，我设法找到了导致这种情况的代码，直到那时我才注意到我收到了这个警告:

In the end, I managed to find the code that caused this, and only then I noticed that I was getting this warning:

C++: warning: C4930: prototyped function not called (was a variable definition intended?)

奇怪的是当我更改代码时:

What's weird is when I changed the code from:

MyClass foo();

到

MyClass foo;

我确实遇到了编译器错误.

I did get a compiler error.

谁能给我解释一下为什么编译器突然开始奇怪了，是bug还是什么?

Can someone explain to me why the compiler suddenly started acting strange, is it a bug or something?

推荐答案

这个

MyClass foo();

是返回类型为 MyClass 且不接受参数的函数声明..

is a function declaration that has return type MyClass and does not accept arguments..

这个

MyClass foo;

是一个对象定义.由于您的类 MyClass 没有默认构造函数，因此编译器会发出错误.

is an object definition. As your class MyClass has no the default constructor the compiler issues an error.

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