c++ - c 语言 struct 声明格式

Question

请问一下，下面代码第五行的语法是什么意思呢？

struct ListNode {
public:
    int val;
    ListNode *next;
    ListNode(int x) : val(x), next(NULL) {}
};

Answer 1

This is C++, not C.

Answer 2

C++ structures are slightly different from C structures: C++ structures extend C structures and can have member functions. Therefore, a C++ structure is more like a class, except that all its members are public by default, which is exactly the opposite of a class.
Line 5 in the code is the constructor, followed by ":" is the parameter list of the constructor, which is used to initialize member variables.

Answer 3

Isn’t this the linked list node given on LeetCode? The fifth line is the constructor.

Answer 4

It’s obvious if you understand struct as class

Answer 5

The fifth line is the constructor in C++

Answer 6

This is C++, the fifth line is the constructor of the class, which is initialized using the initialization list. Struct and class in C++ are similar (find the specific differences by yourself), but functions cannot be defined in struct in C language.

Answer 7

This is C++. Class definitions in C++ can be struct or class. The difference is that struct members default to public and class defaults to private.

ListNode(int x) : val(x), next(NULL) {}

is the constructor of C++, and val(x), next(NULL) represents initialization.