在 C++ 中打印链接列表
本文将介绍几种在 C++ 中打印链接列表元素的方法。
使用自定义函数打印链接列表中的元素
在下面的例子中，我们手动构建一个链接列表数据结构，用任意值初始化它，然后将元素打印到控制台。实现的结构是一个单一的链接列表，有三个数据成员，分别称为 city、country 和 key。
函数 addNewNode 用于在链接列表中构造一个新元素。它以 Node* 参数作为构建新节点的地址，以及需要为其数据成员分配的 3 个对应值。
由于我们是手动构建数据结构，我们需要利用动态内存分配。因此，在程序退出之前，需要另一个函数 freeNodes 来释放链表。
一旦完成了链接列表的初始化，我们就可以在循环中调用 printNodeData 函数来打印从 vector 对中推送到列表中的相同数量的元素。该函数只取类型为 Node*的参数，并调用 cout 将每个数据成员输出到控制台。这个函数的缺点是，用户每次需要打印元素时，都需要担心是否正确迭代到链接列表中。
#include<iostream>
#include<string>
#include<vector>
using std::cout; using std::cin;
using std::endl; using std::string;
using std::vector; using std::pair;
struct Node {
struct Node *next{};
string city;
string country;
int key{};
};
struct Node *addNewNode(struct Node *node, int key, string &city, string &country) {
node->next = new Node;
node->next->key = key;
node->next->city = city;
node->next->country = country;
return node;
}
void freeNodes(struct Node *node) {
struct Node *tmp = nullptr;
while (node) {
tmp = node;
node = node->next;
delete tmp;
}
}
void printNodeData(struct Node *node) {
cout << "key: " << node->key << endl
<< "city: " << node->city << endl
<< "county: " << node->country << endl << endl;
}
int main() {
struct Node *tmp, *root;
struct Node *end = nullptr;
vector<pair<string, string>> list = {{"Tokyo", "Japan"},
{"New York", "United States"},
{"Mexico City", "Mexico"},
{"Tangshan", "China"},
{"Tainan", "Taiwan"}};
root = new Node;
tmp = root;
for (int i = 0; i < list.size(); ++i) {
tmp = addNewNode(tmp, i+1, list[i].first, list[i].second);
tmp = tmp->next;
}
tmp = root->next;
for (const auto &item : list) {
printNodeData(tmp);
tmp = tmp->next;
}
freeNodes(root->next);
delete root;
return EXIT_SUCCESS;
}
输出：
key: 1
city: Tokyo
county: Japan
...
使用自定义的函数打印链接列表中的所有元素
print 函数更好的实现是只调用一次的函数。printNodes 函数被定义为 void 类型，它不向调用者返回任何东西。它正好需要一个类型为 Node*的参数，类似于前面的函数，它自己在链接列表中进行迭代。注意，调用 freeNodes 函数还不足以清理数据结构使用的所有动态内存。从 main 函数中分配的 root 指针也需要释放，否则，内存泄漏将不可避免。
#include<iostream>
#include<string>
#include<vector>
using std::cout; using std::cin;
using std::endl; using std::string;
using std::vector; using std::pair;
struct Node {
struct Node *next{};
string city;
string country;
int key{};
};
struct Node *addNewNode(struct Node *node, int key, string &city, string &country) {
node->next = new Node;
node->next->key = key;
node->next->city = city;
node->next->country = country;
return node;
}
void freeNodes(struct Node *node) {
struct Node *tmp = nullptr;
while (node) {
tmp = node;
node = node->next;
delete tmp;
}
}
void printNodes(struct Node *node) {
while (node){
cout << "key: " << node->key << endl
<< "city: " << node->city << endl
<< "county: " << node->country << endl << endl;
node = node->next;
}
}
int main() {
struct Node *tmp, *root;
struct Node *end = nullptr;
vector<pair<string, string>> list = {{"Tokyo", "Japan"},
{"New York", "United States"},
{"Mexico City", "Mexico"},
{"Tangshan", "China"},
{"Tainan", "Taiwan"}};
root = new Node;
tmp = root;
for (int i = 0; i < list.size(); ++i) {
tmp = addNewNode(tmp, i+1, list[i].first, list[i].second);
tmp = tmp->next;
}
printNodes(root->next);
freeNodes(root->next);
delete root;
return EXIT_SUCCESS;
}
输出：
key: 1
city: Tokyo
county: Japan
...
Founder of DelftStack.com. Jinku has worked in the robotics and automotive industries for over 8 years. He sharpened his coding skills when he needed to do the automatic testing, data collection from remote servers and report creation from the endurance test. He is from an electrical/electronics engineering background but has expanded his interest to embedded electronics, embedded programming and front-/back-end programming.
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