title: "How to get a filename without extension in Go"
date: 2021-02-12T21:41:05+08:00
draft: true
tags: ['go']
author: "dadigang"
author_cn: "大地缸"
personal: "http://www.real007.cn"

关于作者

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How to get a filename without extension in Go

If you want to grab the name of a file without its extension, you can
take a slice of the complete string as shown below:

main.go

func fileNameWithoutExtSliceNotation(fileName string) string {
    return fileName[:len(fileName)-len(filepath.Ext(fileName))]
}

func main() {
    fmt.Println(fileNameWithoutExtSliceNotation("abc.txt")) // abc
}

In this case, the extension length is subtracted from the length of the full
string and the result is used to create a substring that excludes the
extension.

Another way is to use the
strings.TrimSuffix method to
remove the trailing suffix string specified in its second argument:

main.go

func fileNameWithoutExtTrimSuffix(fileName string) string {
    return strings.TrimSuffix(fileName, filepath.Ext(fileName))
}

func main() {
    fmt.Println(fileNameWithoutExtTrimSuffix("abc.txt")) // abc
}

This method is a arguably more readable than the previous one, but it’s also
slower because TrimSuffix needs to make sure the suffix matches before
removal. Here’s a
benchmark
that shows how the slice notation method is approximately twice as fast as the trim suffix
method:

$ go test -bench=.
goos: linux
goarch: amd64
pkg: github.com/ayoisaiah/demo
BenchmarkFileNameWithoutExtSliceNotation-4      201546076            5.91 ns/op
BenchmarkFileNameWithoutExtTrimSuffix-4         100000000           12.1 ns/op
PASS
ok      github.com/ayoisaiah/demo   3.017s

Thanks for reading, and happy coding!

import (
      "path"
      "strings"
)

func FilenameWithoutExtension(fn string) string {
      return strings.TrimSuffix(fn, path.Ext(fn))
}