如何从字符串中删除最后4个字符？

Question

我想从一个字符串中删除最后4个字符，因此"test.txt"变成了"test"。

package main

import (
    "fmt"
    "strings"
)

func main() {
    file := "test.txt"
    fmt.Print(strings.TrimSuffix(file, "."))
}

- KainAlive

Answer 1

这将安全地删除任何点扩展名，并且如果未找到扩展名，则会容忍：

func removeExtension(fpath string) string {
        ext := filepath.Ext(fpath)
        return strings.TrimSuffix(fpath, ext)
}

示例代码: Playground.

表格测试:

/www/main.js                             -> '/www/main'
/tmp/test.txt                            -> '/tmp/test'
/tmp/test2.text                          -> '/tmp/test2'
/tmp/test3.verylongext                   -> '/tmp/test3'
/user/bob.smith/has.many.dots.exe        -> '/user/bob.smith/has.many.dots'
/tmp/zeroext.                            -> '/tmp/zeroext'
/tmp/noext                               -> '/tmp/noext'
                                         -> ''

- colm.anseo

Answer 2

虽然已经有一个被接受的答案，但我想分享一些用于字符串操作的切片技巧。

1. Remove last n characters from a string

   As the title says, remove the last 4 characters from a string, it is very common usage of slices, ie,

   file := "test.txt"
   fmt.Println(file[:len(file)-4]) // you can replace 4 with any n
   

   Output:

   test
   

   Playground example.

2. Remove file extensions:

   From your problem description, it looks like you are trying to trim the file extension suffix (ie, .txt) from the string.

   For this, I would prefer @colminator's answer from above, which is

   file := "test.txt"
   fmt.Println(strings.TrimSuffix(file, filepath.Ext(file)))
   

- Abdullah Al Maruf - Tuhin

Answer 3

您可以使用此方法删除最后一个 "." 之后的所有内容。
go playground

package main

import (
    "fmt"
    "strings"
)

func main() {
    sampleInput := []string{
    "/www/main.js",
    "/tmp/test.txt",
    "/tmp/test2.text",
    "/tmp/test3.verylongext",
    "/user/bob.smith/has.many.dots.exe",
    "/tmp/zeroext.",
    "/tmp/noext",
    "",
    "tldr",
    }
    for _, str := range sampleInput {
        fmt.Println(removeExtn(str))
    }
}

func removeExtn(input string) string {
    if len(input) > 0 {
        if i := strings.LastIndex(input, "."); i > 0 {
            input = input[:i]
        }
    }
    return input
}

- Shubham Srivastava

---

请记得检查字符串中是否存在该字符。另外，点号也可能出现在目录名称中，因此如果您正在检查路径而不是文件名，则应调整此代码。 - boreq

这段程序会在没有点的文件中引发panic：https://play.golang.org/p/EZit4VT16OU - colm.anseo