How To Convert a Zero-Terminated Byte Array to a String in Go

Venter C.

—November 15, 2024

The ProblemThe Problem

When working with C libraries or system calls in Go, you encounter a zero-terminated byte array.

The SolutionThe Solution

A zero-terminated byte array is a sequence of bytes that end with a null byte (0x00). This is a common way to represent strings in C, using a null byte to mark the end of a string.

You can use the bytes.IndexByte function to find the position of the null byte, then use the string type conversion to convert the byte array to a string.

Consider the following example:

package main

import (
    "bytes"
    "fmt"
)

func ZeroTerminatedToString(byteArray []byte) string {
    nullIndex := bytes.IndexByte(byteArray, 0) // Find the first occurrence of the null byte (\x00)
    if nullIndex == -1 {
        return string(byteArray) // No null terminator found, convert entire slice
    }
    return string(byteArray[:nullIndex]) // Slice up to the null terminator
}

func main() {
    // Example byte array with a zero-terminator
    byteArray := []byte{'H', 'e', 'l', 'l', 'o', 0, 'W', 'o', 'r', 'l', 'd'}
    str := ZeroTerminatedToString(byteArray)
    fmt.Println(str)
}

This returns the following output:

Hello

This approach ensures that only the first part of the byte array, up to the first zero byte, is considered. If your input is guaranteed to have a null terminator, this function will safely extract the intended string.

Further readingFurther reading

• The Go bytes package documentation
• The Go IndexBytes function documentation