How to find the index value of any element in slice of bytes in Golang?

Last Updated : 12 Jul, 2025

In Go language slice is more powerful, flexible, convenient than an array, and is a lightweight data structure. The slice is a variable-length sequence which stores elements of a similar type, you are not allowed to store different type of elements in the same slice. In the Go slice of bytes, you can find the first index value of any specified instance in the given slice using IndexAny() function. This function returns the byte index of the first occurrence in the original slice of any of the Unicode code points in chars. If the Unicode code point from chars is not available or empty in the original slice, then this method will return -1. It is defined under the bytes package so, you have to import bytes package in your program for accessing IndexAny function. Syntax:

func IndexAny(ori_slice []byte, val string) int

Here, ori_slice is the original string and val is a string, whose we want to find the first index value. Let us discuss this concept with the help of the given examples: Example 1:

// Go program to illustrate the concept
// of the index in the slice of bytes
package main

import (
    "bytes"
    "fmt"
)

func main() {

    // Creating and finding the index
    // of the slice of bytes
    // Using IndexAny function
    res1 := bytes.IndexAny([]byte("****Welcome to GeeksforGeeks****"),
                                                              "Gjskf")
    
    res2 := bytes.IndexAny([]byte("Learning how to trim a slice of bytes"),
                                                                   "qoxz")
    
    res3 := bytes.IndexAny([]byte("GeeksforGeeks, Geek"), 
                                                "HELLO")

    // Display the results
    fmt.Printf("\n\nFinal Value:\n")
    fmt.Printf("\nSlice 1: %d", res1)
    fmt.Printf("\nSlice 2: %d", res2)
    fmt.Printf("\nSlice 3: %d", res3)
}

Output:

Final Value:

Slice 1: 15
Slice 2: 10
Slice 3: -1

Example 2:

// Go program to illustrate the concept
// of the index in the slice of bytes
package main

import (
    "bytes"
    "fmt"
)

func main() {

    // Creating and initializing 
    // the slice of bytes
    // Using shorthand declaration
    slice_1 := []byte{'!', '!', 'G', 'e', 'e', 'k', 's', 'f', 
                 'o', 'r', 'G', 'e', 'e', 'k', 's', '#', '#'}
    
    slice_2 := []byte{'A', 'p', 'p', 'l', 'e'}
    
    slice_3 := []byte{'%', 'g', 'e', 'e', 'k', 's', '%'}

    // Displaying slices
    fmt.Println("Original Slice:")
    fmt.Printf("Slice 1: %s", slice_1)
    fmt.Printf("\nSlice 2: %s", slice_2)
    fmt.Printf("\nSlice 3: %s", slice_3)

    // Finding the index of
    // the slice of bytes
    // Using IndexAny function
    res1 := bytes.IndexAny(slice_1, "eks")
    res2 := bytes.IndexAny(slice_2, "lqzxm")
    res3 := bytes.IndexAny(slice_3, "xxxxx")

    // Display the results
    fmt.Printf("\n\nLast Index:\n")
    fmt.Printf("\nSlice 1: %d", res1)
    fmt.Printf("\nSlice 2: %d", res2)
    fmt.Printf("\nSlice 3: %d", res3)

}

Output:

Original Slice:
Slice 1: !!GeeksforGeeks##
Slice 2: Apple
Slice 3: %geeks%

Last Index:

Slice 1: 3
Slice 2: 3
Slice 3: -1

How to find the last index value in slice of bytes in Golang?

ankita_saini

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How to find the index value of any element in slice of bytes in Golang?

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