Check if the Slice of bytes starts with specified prefix in Golang

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 check whether the given slice begins with the specified prefix or not with the help of HasPrefix() function. This function returns true if the given slice starts with the specified prefix or return false if the given slice does not start with the specified prefix. It is defined under the bytes package so, you have to import bytes package in your program for accessing HasPrefix function.

Syntax:

func HasPrefix(slice_1, pre []byte) bool

Here, slice_1 is the original slice of bytes and pre is the prefix which is also a slice of bytes. The return type of this function is of the bool type. Let us discuss this concept with the help of an example:



Example:

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// Go program to illustrate how to check the
// given slice starts with the specified prefix
package main
  
import (
    "bytes"
    "fmt"
)
  
func main() {
  
    // Creating and initializing
    // 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'}
  
    // Checking whether the given slice starts 
    // with the specified prefix or not
    // Using  HasPrefix () function
    res1 := bytes.HasPrefix(slice_1, []byte("G"))
    res2 := bytes.HasPrefix(slice_2, []byte("O"))
    res3 := bytes.HasPrefix([]byte("Hello! I am Apple."), []byte("Hello"))
    res4 := bytes.HasPrefix([]byte("Hello! I am Apple."), []byte("Welcome"))
    res5 := bytes.HasPrefix([]byte("Hello! I am Apple."), []byte("H"))
    res6 := bytes.HasPrefix([]byte("Hello! I am Apple."), []byte("X"))
    res7 := bytes.HasPrefix([]byte("Geeks"), []byte(""))
  
    // Displaying results
    fmt.Println("Result_1: ", res1)
    fmt.Println("Result_2: ", res2)
    fmt.Println("Result_3: ", res3)
    fmt.Println("Result_4: ", res4)
    fmt.Println("Result_5: ", res5)
    fmt.Println("Result_6: ", res6)
    fmt.Println("Result_7: ", res7)
  
}

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Output:

Result_1:  true
Result_2:  false
Result_3:  true
Result_4:  false
Result_5:  true
Result_6:  false
Result_7:  true


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