Extracting substrings in Go

Question

I\'m trying to read an entire line from the console (including whitespace), then process it. Using bufio.ReadString, the newline character is read together with the input, s

Answer 1

This is the simple one to perform substring in Go

package main

import "fmt"

var p = fmt.Println

func main() {

  value := "address;bar"

  // Take substring from index 2 to length of string
  substring := value[2:len(value)]
  p(substring)

}

Answer 2

To avoid a panic on a zero length input, wrap the truncate operation in an if

input, _ := src.ReadString('\n')
var inputFmt string
if len(input) > 0 {
    inputFmt = input[:len(input)-1]
}
// Do something with inputFmt

Answer 3

To get substring

1. find position of "sp"

2. cut string with array-logical

https://play.golang.org/p/0Redd_qiZM

Answer 4

It looks like you're confused by the working of slices and the string storage format, which is different from what you have in C.

• any slice in Go stores the length (in bytes), so you don't have to care about the cost of the len operation : there is no need to count
• Go strings aren't null terminated, so you don't have to remove a null byte, and you don't have to add 1 after slicing by adding an empty string.

To remove the last char (if it's a one byte char), simply do

inputFmt:=input[:len(input)-1]

Answer 5

WARNING: operating on strings alone will only work with ASCII and will count wrong when input is a non-ASCII UTF-8 encoded character, and will probably even corrupt characters since it cuts multibyte chars mid-sequence.

Here's a UTF-8-aware version:

func substr(input string, start int, length int) string {
    asRunes := []rune(input)

    if start >= len(asRunes) {
        return ""
    }

    if start+length > len(asRunes) {
        length = len(asRunes) - start
    }

    return string(asRunes[start : start+length])
}

Answer 6

Go strings are not null terminated, and to remove the last char of a string you can simply do:

s = s[:len(s)-1]