如何在GoLang中比较字符串？

Question

I am unable to produce a 'true' result when it comes to Go string comparison. I wrote the following to explain the issue and attached a screenshot of the output

// string comparison in Go
package main
import "fmt"
import "bufio"
import "os"

func main() {
    var isLetterA bool 

    fmt.Println("Enter the letter a")
    reader := bufio.NewReader(os.Stdin)
    input, _ := reader.ReadString('
')

    if(input == "a") {
        isLetterA = true
    } else {
        isLetterA = false 
    }

    fmt.Println("You entered",input)
    fmt.Println("Is it the letter a?",isLetterA)

}

Answer 1

== is the correct operator to compare strings in Go. However, the strings that you read from STDIN with reader.ReadString do not contain "a", but "a " (if you look closely, you'll see the extra line break in your example output).

You can use the strings.TrimRight function to remove trailing whitespaces from your input:

if strings.TrimRight(input, "
") == "a" {
    // ...
}

Answer 2

For the Platform Independent Users or Windows users, what you can do is:

import runtime:

import (
    "runtime"
    "strings"
)

and then trim the string like this:

if runtime.GOOS == "windows" {
  input = strings.TrimRight(input, "
")
} else {
  input = strings.TrimRight(input, "
")
}

now you can compare it like that:

if strings.Compare(input, "a") == 0 {
  //....yourCode
}

This is a better approach when you're making use of STDIN on multiple platforms.

Explanation

This happens because on windows lines end with " " which is known as CRLF, but on UNIX lines end with " " which is known as LF and that's why we trim " " on unix based operating systems while we trim " " on windows.

Answer 3

The content inside strings in Golang can be compared using == operator. If the results are not as expected there may be some hidden characters like , , spaces, etc. So as a general rule of thumb, try removing those using functions provided by strings package in golang.

For Instance, spaces can be removed using strings.TrimSpace function. You can also define a custom function to remove any character you need. strings.TrimFunc function can give you more power.