Does Go Have an Equivalent to Python's 'if x in' for Array Membership?

How to Find Array Elements Like Python's "if x in" Construct in Go

In Python, you can easily check if an element exists in an array using the "if x in" construct. Does Go offer a similar mechanism for checking array membership without iterating through the entire array?

Answer

Go does not have a direct equivalent of Python's "if x in" construct for arrays. However, starting with Go 1.18, you can use the slices.Contains function for slices to achieve a similar result:

if slices.Contains(array, x) {
    // do something
}

Pre-Go 1.18 Solution

Prior to Go 1.18, there was no built-in operator for checking array membership. You had to iterate over the array and use a custom function like the following:

func stringInSlice(a string, list []string) bool {
    for _, b := range list {
        if b == a {
            return true
        }
    }
    return false
}

Alternative Approach: Maps

To avoid the need for iteration, you can utilize a map instead of an array or slice:

visitedURL := map[string]bool{
    "http://www.google.com": true,
    "https://paypal.com": true,
}
if visitedURL[thisSite] {
    fmt.Println("Already been here.")
}

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