我使用reflect包创建了以下Contains函数。 此函数可用于各种类型，如int32或struct等。

// Contains returns true if an element is present in a slice
func Contains(list interface{}, elem interface{}) bool {
    listV := reflect.ValueOf(list)

    if listV.Kind() == reflect.Slice {
        for i := 0; i < listV.Len(); i++ {
            item := listV.Index(i).Interface()

            target := reflect.ValueOf(elem).Convert(reflect.TypeOf(item)).Interface()
            if ok := reflect.DeepEqual(item, target); ok {
                return true
            }
        }
    }
    return false
}

contains函数的用法如下

// slice of int32
containsInt32 := Contains([]int32{1, 2, 3, 4, 5}, 3)
fmt.Println("contains int32:", containsInt32)

// slice of float64
containsFloat64 := Contains([]float64{1.1, 2.2, 3.3, 4.4, 5.5}, 4.4)
fmt.Println("contains float64:", containsFloat64)


// slice of struct
type item struct {
    ID   string
    Name string
}
list := []item{
    item{
        ID:   "1",
        Name: "test1",
    },
    item{
        ID:   "2",
        Name: "test2",
    },
    item{
        ID:   "3",
        Name: "test3",
    },
}
target := item{
    ID:   "2",
    Name: "test2",
}
containsStruct := Contains(list, target)
fmt.Println("contains struct:", containsStruct)

// Output:
// contains int32: true
// contains float64: true
// contains struct: true

详情请点击此处: https://github.com/glassonion1/xgo/blob/main/contains.go

如果切片已排序，则排序包中实现了二进制搜索。

不，这样的方法不存在，但是写起来很简单:

func contains(s []int, e int) bool {
    for _, a := range s {
        if a == e {
            return true
        }
    }
    return false
}

如果查找是代码的重要部分，则可以使用映射，但映射也有成本。

go样式:

func Contains(n int, match func(i int) bool) bool {
    for i := 0; i < n; i++ {
        if match(i) {
            return true
        }
    }
    return false
}


s := []string{"a", "b", "c", "o"}
// test if s contains "o"
ok := Contains(len(s), func(i int) bool {
    return s[i] == "o"
})

func Contain(target interface{}, list interface{}) (bool, int) {
    if reflect.TypeOf(list).Kind() == reflect.Slice || reflect.TypeOf(list).Kind() == reflect.Array {
        listvalue := reflect.ValueOf(list)
        for i := 0; i < listvalue.Len(); i++ {
            if target == listvalue.Index(i).Interface() {
                return true, i
            }
        }
    }
    if reflect.TypeOf(target).Kind() == reflect.String && reflect.TypeOf(list).Kind() == reflect.String {
        return strings.Contains(list.(string), target.(string)), strings.Index(list.(string), target.(string))
    }
    return false, -1
}

如果你有一个字节切片，你可以使用bytes包:

package main
import "bytes"

func contains(b []byte, sub byte) bool {
   return bytes.Contains(b, []byte{sub})
}

func main() {
   b := contains([]byte{10, 11, 12, 13, 14}, 13)
   println(b)
}

或suffixarray包:

package main
import "index/suffixarray"

func contains(b []byte, sub byte) bool {
   return suffixarray.New(b).Lookup([]byte{sub}, 1) != nil
}

func main() {
   b := contains([]byte{10, 11, 12, 13, 14}, 13)
   println(b)
}

如果你有一个int片，你可以使用intsets包:

package main
import "golang.org/x/tools/container/intsets"

func main() {
   var s intsets.Sparse
   for n := 10; n < 20; n++ {
      s.Insert(n)
   }
   b := s.Has(16)
   println(b)
}

https://golang.org/pkg/bytes https://golang.org/pkg/index/suffixarray https://pkg.go.dev/golang.org/x/tools/container/intsets