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xpt
Asked: 2025-01-02 11:00:10 +0800 CST

在 Go 中使用反射，如何迭代已知切片

  • 772

和

    m := map[string]any{"a": 1, "b": 2, "c": []int{2, 3, 4}}
    v := reflect.ValueOf(m)

如何在"c"中进行迭代v？

参见https://go.dev/play/p/KQ_UNjm-Vqd

package main

import (
    "fmt"
    "reflect"
)

func main() {
    m := map[string]any{"a": 1, "b": 2, "c": []int{2, 3, 4}}
    v := reflect.ValueOf(m)

    // Access the "c" key
    cKey := reflect.ValueOf("c")
    cValue := v.MapIndex(cKey)

    if cValue.IsValid() && cValue.Kind() == reflect.Slice {
        fmt.Println("Iterating through 'c':")
        for i := 0; i < cValue.Len(); i++ {
            fmt.Println(cValue.Index(i).Interface())
        }
    } else {
        fmt.Println("'c' is not a valid slice or key does not exist.")
    }

    if !cValue.IsValid() {
        fmt.Println("Key 'c' not found in the map")
        return
    }
    if cValue.Kind() != reflect.Slice {
        fmt.Println("Value for key 'c' is not a slice")
        return
    }
}
loops

2 个回答

  1. Best Answer

    （我在这上面花了太长时间）

    package main

import (
"fmt"
"reflect"
)

func main() {
m := map[string]any{"a": 1, "b": 2, "c": []int{2, 3, 4}}
v := reflect.ValueOf(m)

// Access the "c" key
cKey := reflect.ValueOf("c")
cValue := v.MapIndex(cKey)

if !cValue.IsValid() {
    fmt.Println("Key 'c' not found in the map. ")
    return
}

// If the value is an interface, unwrap it
if cValue.Kind() == reflect.Interface {
    cValue = cValue.Elem()
}

if cValue.Kind() != reflect.Slice {
    fmt.Println("Value for key 'c' is not a slice. ")
    return
}

fmt.Println("Iterating... ")
for i := 0; i < cValue.Len(); i++ {
    fmt.Printf("Element %d: %v\n", i, cValue.Index(i).Interface())
}
}
    • 1

  2. 要迭代reflect.Value表示 的 a Map，我们可以利用包MapKeys中的方法reflect。这是一个完整的示例：

    // Check if the reflect.Value represents a Map
if v.Kind() == reflect.Map {
    // Get all the keys in the map as a slice of reflect.Value
    keys := v.MapKeys()
    for _, key := range keys {
        // Convert the reflect.Value representation of the key back to its original type
        keyStr, ok := key.Interface().(string)
        if !ok {
            fmt.Printf("Key is not a string: %v\n", key)
            continue
        }

        // Retrieve the value associated with the key
        value := v.MapIndex(key)

        // Extract the underlying value from reflect.Value and print the key-value pair
        fmt.Printf("Key: %s, Value: %v\n", keyStr, value.Interface())
    }
} else {
    fmt.Println("v is not a map")
}

    实时代码

    关键点

    1. 在使用特定于 Map 的方法之前检查 v.Kind() 类似MapKeys()或的方法MapIndex()会对非 Map 值产生恐慌

    资料来源：

    • 0

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