Golang : How to check if a string with spaces in between is numeric?



Tags : golang isdigit numeric spaces unicode

Ok, I need a function that will determine if an input string is indeed numeric or not. The "standard way" of checking if an input string is make up of digits is to use strconv.ParseFloat() function. However, this method will fail if the input string has spaces in between.

Below is my own function that uses the unicode package to determine if an input string is truly numeric or not.

Here you go!


 package main

 import (
  "fmt"
  "strconv"
  "unicode"
 )

 func main() {
  str1 := "123"
  checkNumeric(str1)
  fmt.Println(str1, IsNumeric(str1))

  str2 := "12a3"
  checkNumeric(str2)
  fmt.Println(str2, IsNumeric(str2))

  str3 := "abcd"
  checkNumeric(str3)
  fmt.Println(str3, IsNumeric(str3))

  str4 := "12 3" // space will cause the "standard way" test to fail, trim space first if needed

  checkNumeric(str4) // more robust, this is what I need
  fmt.Println(str4, IsNumeric(str4)) // the "standard way" will mark this is false

  str41 := "12 3 45 6 7"

  checkNumeric(str41)
  fmt.Println(str41, IsNumeric(str41))

  str43 := "12 3 a 45 6 7"

  checkNumeric(str43)
  fmt.Println(str43, IsNumeric(str43))

  str5 := "12.3"
  checkNumeric(str5)
  fmt.Println(str5, IsNumeric(str5))

  str6 := "-123.4"
  checkNumeric(str6)
  fmt.Println(str6, IsNumeric(str6))
 }

 func checkNumeric(input string) {
  var def bool = false

  for _, v := range input {
 if unicode.IsDigit(v) {
 def = true
 } else if unicode.IsPunct(v) {
 continue // skip
 } else if unicode.IsSpace(v) {
 continue // skip
 } else {
 def = false
 break
 }
  }

  fmt.Println(input, def)
 }

 func IsNumeric(s string) bool {
  _, err := strconv.ParseFloat(s, 64)
  return err == nil
 }

Output:

123 true

123 true

12a3 false

12a3 false

abcd false

abcd false

12 3 true

12 3 false

12 3 45 6 7 true

12 3 45 6 7 false

12 3 a 45 6 7 false

12 3 a 45 6 7 false

12.3 true

12.3 true

-123.4 true

-123.4 true

References :

https://www.socketloop.com/tutorials/golang-natural-string-sorting-example

https://www.socketloop.com/tutorials/golang-how-to-check-if-input-from-os-args-is-integer

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  See also : Golang : Number guessing game with user input verification example



Tags : golang isdigit numeric spaces unicode

By Adam Ng(黃武俊)

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