Some languages have an in operator that checks if a collection contains a certain value, Go does not.
In Go the same functionality is provided by a Contains function.
Depending on your Go version you can use a different approach:
- In 1.21 and later, you can use the
Containsfunction in theslicespackage in the standard library. - For earlier versions, you can find the same function in the experimental
slicespackage.
These functions compare the slice values using ==. Depending on your situation you may want to compare in a different way. The ContainsFunc function allows you to specify a custom comparison function.
If you are using a Go version that does not support generics, you can always implement your own SliceContains function. See the example below:
main.go
package main
import (
"fmt"
"slices"
)
func main() {
s := []string{"🌱", "🪡", "🌱"}
x := "🪡"
y := "🙈"
fmt.Println("slices.Contains:")
fmt.Printf("s contains \"%s\"? %v\n", x, slices.Contains(s, x))
fmt.Printf("s contains \"%s\"? %v\n", y, slices.Contains(s, y))
fmt.Println("---")
fmt.Println("SliceContains:")
fmt.Printf("s contains \"%s\"? %v\n", x, SliceContains(s, x))
fmt.Printf("s contains \"%s\"? %v\n", y, SliceContains(s, y))
}
// SliceContains returns true if s contains v.
func SliceContains(s []string, v string) bool {
for _, vs := range s {
if vs == v {
return true
}
}
return false
}
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