c++中map容器怎么遍历

在 C++ 中有 STL（Standard Template Library）标准模板库，其中包含了很多方便实用的容器，map 就是其中之一。而在 C 语言中，并没有直接提供 map 容器，但是可以使用结构体和链表等数据结构来实现类似的功能。

如果你想遍历 C++ 中的 map 容器，可以使用迭代器来实现，代码示例如下：

#include <iostream>
#include <map>
using namespace std;

int main() {
    map<string, int> my_map;

    my_map["apple"] = 3;
    my_map["banana"] = 6;
    my_map["orange"] = 9;

    for (auto iter = my_map.begin(); iter != my_map.end(); ++iter) {
        cout << "key: " << iter->first << ", value: " << iter->second << endl;
    }

    return 0;
}

输出结果为：

key: apple, value: 3
key: banana, value: 6
key: orange, value: 9

如果你想在 C 语言中实现类似的功能，可以使用结构体和链表来实现，代码示例如下：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

struct node {
    char key[20];
    int value;
    struct node* next;
};

void map_put(struct node** map, char* key, int value) {
    struct node* new_node = (struct node*)malloc(sizeof(struct node));
    strcpy(new_node->key, key);
    new_node->value = value;
    new_node->next = NULL;

    if (*map == NULL) {
        *map = new_node;
        return;
    }

    struct node* cur_node = *map;
    while (cur_node->next != NULL) {
        if (strcmp(cur_node->key, key) == 0) {
            cur_node->value = value;
            return;
        }
        cur_node = cur_node->next;
    }

    if (strcmp(cur_node->key, key) == 0) {
        cur_node->value = value;
        free(new_node);
        return;
    }

    cur_node->next = new_node;
}

int map_get(struct node* map, char* key) {
    struct node* cur_node = map;
    while (cur_node != NULL) {
        if (strcmp(cur_node->key, key) == 0) {
            return cur_node->value;
        }
        cur_node = cur_node->next;
    }
    return -1;
}

void map_remove(struct node** map, char* key) {
    struct node* cur_node = *map;
    struct node* prev_node = NULL;

    while (cur_node != NULL) {
        if (strcmp(cur_node->key, key) == 0) {
            if (prev_node == NULL) {
                *map = cur_node->next;
            } else {
                prev_node->next = cur_node->next;
            }
            free(cur_node);
            return;
        }
        prev_node = cur_node;
        cur_node = cur_node->next;
    }
}

void map_clear(struct node** map) {
    struct node* cur_node = *map;
    while (cur_node != NULL) {
        struct node* next_node = cur_node->next;
        free(cur_node);
        cur_node = next_node;
    }
    *map = NULL;
}

void map_print(struct node* map) {
    struct node* cur_node = map;
    while (cur_node != NULL) {
        printf("key: %s, value: %d\n", cur_node->key, cur_node->value);
        cur_node = cur_node->next;
    }
}

int main() {
    struct node* my_map = NULL;

    map_put(&my_map, "apple", 3);
    map_put(&my_map, "banana", 6);
    map_put(&my_map, "orange", 9);

    map_print(my_map);

    map_remove(&my_map, "banana");

    printf("\nAfter remove:\n");
    map_print(my_map);

    map_clear(&my_map);

    return 0;
}

输出结果为：

key: apple, value: 3
key: banana, value: 6
key: orange, value: 9

After remove:
key: apple, value: 3
key: orange, value: 9