Golang bytes.CutSuffix Function

The bytes.CutSuffix function in Golang is part of the bytes package and is used to remove a specified suffix from a byte slice. It returns the remaining byte slice after the suffix is removed, along with a boolean indicating whether the suffix was found and removed. If the suffix is not found, the function returns the original byte slice unmodified and a false value.

Table of Contents

  1. Introduction
  2. bytes.CutSuffix Function Syntax
  3. Examples
    • Basic Usage
    • Handling Suffix Not Found
    • Removing File Extensions
  4. Real-World Use Case
  5. Conclusion

Introduction

The bytes.CutSuffix function is useful when you need to check for and remove a specific suffix from a byte slice. This is particularly handy when dealing with strings that may have a known suffix, such as file extensions, trailing characters, or formatted data.

bytes.CutSuffix Function Syntax

The syntax for the bytes.CutSuffix function is as follows:

func CutSuffix(s, suffix []byte) (before []byte, found bool)

Parameters:

  • s: The byte slice to be processed.
  • suffix: The suffix byte slice to be removed from s.

Returns:

  • before: The byte slice after the suffix has been removed. If the suffix is not found, this will be the original byte slice s.
  • found: A boolean value that is true if the suffix was found and removed, and false otherwise.

Examples

Basic Usage

This example demonstrates how to use the bytes.CutSuffix function to remove a specified suffix from a byte slice.

Example

package main

import (
	"bytes"
	"fmt"
)

func main() {
	// Define the main byte slice
	data := []byte("report.pdf")

	// Define the suffix to remove
	suffix := []byte(".pdf")

	// Use bytes.CutSuffix to remove the suffix
	before, found := bytes.CutSuffix(data, suffix)

	// Print the results
	if found {
		fmt.Printf("After suffix removal: %s\n", before)
	} else {
		fmt.Println("Suffix not found.")
	}
}

Output:

After suffix removal: report

Handling Suffix Not Found

This example shows how bytes.CutSuffix behaves when the suffix is not found in the byte slice.

Example

package main

import (
	"bytes"
	"fmt"
)

func main() {
	// Define the main byte slice
	data := []byte("report.pdf")

	// Define a suffix that is not present in the byte slice
	suffix := []byte(".docx")

	// Use bytes.CutSuffix to try to remove the suffix
	before, found := bytes.CutSuffix(data, suffix)

	// Print the results
	if found {
		fmt.Printf("After suffix removal: %s\n", before)
	} else {
		fmt.Println("Suffix not found.")
	}
}

Output:

Suffix not found.

Removing File Extensions

This example demonstrates how to use bytes.CutSuffix to remove file extensions from a list of filenames.

Example

package main

import (
	"bytes"
	"fmt"
)

func main() {
	// List of filenames
	filenames := [][]byte{
		[]byte("report.pdf"),
		[]byte("image.jpg"),
		[]byte("document.txt"),
	}

	// Define the suffixes to remove
	suffixes := [][]byte{
		[]byte(".pdf"),
		[]byte(".jpg"),
		[]byte(".txt"),
	}

	// Process each filename
	for _, filename := range filenames {
		for _, suffix := range suffixes {
			if before, found := bytes.CutSuffix(filename, suffix); found {
				fmt.Printf("Filename: %s, After suffix removal: %s\n", filename, before)
				break
			}
		}
	}
}

Output:

Filename: report.pdf, After suffix removal: report
Filename: image.jpg, After suffix removal: image
Filename: document.txt, After suffix removal: document

Explanation:

  • bytes.CutSuffix checks for the specified suffix in the byte slice.
  • If the suffix is found, it returns the slice with the suffix removed and true.
  • If the suffix is not found, it returns the original slice and false.

Real-World Use Case

Trimming Trailing Characters

In real-world applications, bytes.CutSuffix can be used to trim specific trailing characters from strings, such as removing a trailing slash from a URL or a trailing newline from a text input.

Example: Removing Trailing Slash from a URL

package main

import (
	"bytes"
	"fmt"
)

func main() {
	// Define a URL with a trailing slash
	url := []byte("https://www.example.com/")

	// Define the suffix to remove (trailing slash)
	suffix := []byte("/")

	// Use bytes.CutSuffix to remove the trailing slash
	before, found := bytes.CutSuffix(url, suffix)

	// Print the result
	if found {
		fmt.Printf("URL without trailing slash: %s\n", before)
	} else {
		fmt.Println("Trailing slash not found.")
	}
}

Output:

URL without trailing slash: https://www.example.com

Explanation:

  • The example demonstrates how bytes.CutSuffix can be used to remove a trailing slash from a URL, making it easier to normalize URLs for processing or comparison.

Conclusion

The bytes.CutSuffix function in Go is a convenient tool for removing specific suffixes from byte slices. Whether you're processing filenames, URLs, or any other structured data with known suffixes, bytes.CutSuffix provides an efficient way to handle these tasks. 

By returning both the modified slice and a boolean indicating whether the suffix was found, it allows for flexible and robust handling of various input scenarios. This function is particularly useful in text processing, data parsing, and handling standardized formats.

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