Go语言Map操作：深入理解删除行为与正确遍历姿势

package main

import "fmt"

func main() {
    mapp := make(map[int]int)
    fmt.Println("before removal:")

    for i := 1; i < 7; i++ {
        mapp[i] = i
    }
    fmt.Println(mapp) // 输出: map[1:1 2:2 3:3 4:4 5:5 6:6] (顺序可能不同)

    delete(mapp, 2)
    fmt.Println("\nafter the removal:")
    // 尝试以循环访问原始索引的方式遍历
    for i := 1; i < 7; i++ {
        fmt.Println(i, mapp[i])
    }
}

before removal:
map[1:1 2:2 3:3 4:4 5:5 6:6]

after the removal:
1 1
2 0  // 键2已被删除，访问返回零值
3 3
4 4
5 5
6 6

package main

import "fmt"

func main() {
    mapp := make(map[int]int)
    for i := 1; i < 7; i++ {
        mapp[i] = i
    }
    fmt.Println("Original map:", mapp)

    delete(mapp, 2)
    fmt.Println("Map after deleting key 2:", mapp)

    fmt.Println("\nIterating and checking for existence:")
    // 遍历原始的键范围，并检查每个键是否存在
    for i := 1; i < 7; i++ {
        if value, exists := mapp[i]; exists {
            fmt.Println(i, value)
        }
    }

    fmt.Println("\nIterating over map directly (recommended for map content):")
    // 直接使用for...range遍历map，它只会遍历存在的键值对
    for key, value := range mapp {
        fmt.Println(key, value)
    }
}

Original map: map[1:1 2:2 3:3 4:4 5:5 6:6]
Map after deleting key 2: map[1:1 3:3 4:4 5:5 6:6]

Iterating and checking for existence:
1 1
3 3
4 4
5 5
6 6

Iterating over map directly (recommended for map content):
1 1
3 3
4 4
5 5
6 6

package main

import "fmt"

func main() {
    s := []int{1, 2, 3, 4, 5, 6}
    fmt.Println("Original slice:", s)

    // 移除并返回索引为1的元素 (即值2)
    if len(s) > 1 {
        removedElement := s[1] // 获取要移除的元素
        s = append(s[:1], s[2:]...) // 移除索引1的元素，后续元素前移
        fmt.Printf("Removed element: %d, New slice: %v\n", removedElement, s)
    }

    // 模拟从末尾“弹出”
    if len(s) > 0 {
        lastElement := s[len(s)-1]
        s = s[:len(s)-1]
        fmt.Printf("Popped element: %d, New slice: %v\n", lastElement, s)
    }
}

Original slice: [1 2 3 4 5 6]
Removed element: 2, New slice: [1 3 4 5 6]
Popped element: 6, New slice: [1 3 4 5]