在 C++ 中列印連結列表
本文將介紹幾種在 C++ 中列印連結列表元素的方法。
使用自定義函式列印連結列表中的元素
在下面的例子中，我們手動構建一個連結列表資料結構，用任意值初始化它，然後將元素列印到控制檯。實現的結構是一個單一的連結列表，有三個資料成員，分別稱為 city、country 和 key。
函式 addNewNode 用於在連結列表中構造一個新元素。它以 Node* 引數作為構建新節點的地址，以及需要為其資料成員分配的 3 個對應值。
由於我們是手動構建資料結構，我們需要利用動態記憶體分配。因此，在程式退出之前，需要另一個函式 freeNodes 來釋放連結串列。
一旦完成了連結列表的初始化，我們就可以在迴圈中呼叫 printNodeData 函式來列印從 vector 對中推送到列表中的相同數量的元素。該函式只取型別為 Node*的引數，並呼叫 cout 將每個資料成員輸出到控制檯。這個函式的缺點是，使用者每次需要列印元素時，都需要擔心是否正確迭代到連結列表中。
#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;
}
輸出：
key: 1
city: Tokyo
county: Japan
...
使用自定義的函式列印連結列表中的所有元素
print 函式更好的實現是隻呼叫一次的函式。printNodes 函式被定義為 void 型別，它不向呼叫者返回任何東西。它正好需要一個型別為 Node*的引數，類似於前面的函式，它自己在連結列表中進行迭代。注意，呼叫 freeNodes 函式還不足以清理資料結構使用的所有動態記憶體。從 main 函式中分配的 root 指標也需要釋放，否則，記憶體洩漏將不可避免。
#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;
}
輸出：
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.
LinkedIn