数据结构的简略实现---C++

• 节点元素获取： val_get()
• 节点后插入元素: insert_after()
• 节点后删除元素： erase_after()
• 节点后修改元素值: replace_after()

// C++ Single forward linked single_linked_forward_list complementation, only integer elements that are different from each other are allowed.

#ifndef SINGLE_LINKED_FORWARD_LIST_H
#define SINGLE_LINKED_FORWARD_LIST_H
#include        //std::shared_ptr std::make_shared

class single_linked_forward_list {
public:
    friend single_linked_forward_list* init(void);
public:
    // Get value
    int val_get() const
    // Inserting
    void insert_after(int);
    // Removing
    void erase_after(void);
    // Changing
    void replace_after(int);

public:
    // Pointer to the next node
    single_linked_forward_list* next = nullptr;

private:
    int val = 0;
    // Dummy head pointer
    //static single_linked_forward_list* head;
    // Testing of existance
    inline bool exist_this(single_linked_forward_list*);
    inline bool exist_next(single_linked_forward_list*);
    inline bool exist_num(single_linked_forward_list*, int);
};

// Initialization
single_linked_forward_list* init(void);

#endif

#include       // std::cerr std::end
#include "single_linked_forward_list.h"


// PUBLIC MEMBER FUNCTIONS
// Inserting
void single_linked_forward_list::insert_after(int num) {
    // node exist, num not exist
    if (exist_this(this) && !exist_num(this, num)) {
        single_linked_forward_list* temp = new single_linked_forward_list;
        temp->next = this->next;
        this->next = temp;
        this->next->val = num;
        std::cout << "Inserting successed!" << std::endl;
    }
    else {
        std::cerr << "Inserting failed!"
            << std::endl;
    }
    return;
}

// Removing
void single_linked_forward_list::erase_after(void) {
    // Two things node and node->next
    if (exist_this(this) && exist_next(this->next)) {
        this->next = this->next->next;
        std::cout << "Erasing successed!" << std::endl;
    }
    else {
        std::cerr << "Erasing failed!"
            << std::endl;
    }
    return;
}

// Changing
void single_linked_forward_list::replace_after(int num) {
    // Both things node and node->next
    if (exist_this(this) && exist_next(this) && !exist_num(this, num)) {
        if (num == this->next->val) {
            std::cerr << "Value the same, no need to change!" << std::endl;
            return;
        }
        this->next->val = num;
        std::cout << "Replacing successed!" << std::endl;
    }
    else {
        std::cerr << "Replacing failed!"
            << std::endl;
    }
    return;
}

// PRIVATE MEMBER FUNCTIONS
inline bool single_linked_forward_list::exist_this(single_linked_forward_list* node) {
    return (node != nullptr) ? true : false;
}
inline bool single_linked_forward_list::exist_next(single_linked_forward_list* node) {
    return (node->next != nullptr) ? true : false;
}
inline bool single_linked_forward_list::exist_num(single_linked_forward_list* node, int num) {
	// 头指针（首元指针前的）暂未实现，下面的node只能实现从node开始的数值查找
    for (auto i = node; i != nullptr; i = i->next) {
        if (i->val == num)
            return true;
    }
    return false;
}

// Initialization
single_linked_forward_list* init(void) { 
    //single_linked_forward_list::head = new single_linked_forward_list();
    return new single_linked_forward_list();
}
// get value
int single_linked_forward_list::val_get() const {
    if (this == nullptr) {
        std::cerr << "node not exist! -1 will be returned." << std::endl;
        return -1;
    } else {
        return this->val;
    }
}

#include 
#include 
#include "single_linked_forward_list.h"

int main(void) {
    // 初始化
    single_linked_forward_list* list = init();
    
    // 位置2插入两次
    list->insert_after(2);
    list->insert_after(1);
    std::cout << list->val_get() << " " 
              << list->next->val_get() << " " 
              << list->next->next->val_get() << std::endl;
    // 位置2的值替换 
    list->replace_after(3);
    std::cout << list->val_get() << " " 
              << list->next->val_get() << " " 
              << list->next->next->val_get() << std::endl;
    // 删除位置2元素 
    list->erase_after();
    // 注意，下面第三行节点不存在，将打印错误信息
    std::cout << list->val_get() << " " 
              << list->next->val_get() << " " 
              << list->next->next->val_get() << std::endl;
    return 0;
}