Golang : Get all upper case or lower case characters from string example

Problem:

You have a string and you want to get all the uppercase characters in the string. For example, you want to get the characters of A,O and H from the string "Ace Of Hearts" and use the AOH to make a key for your string map. How to do that?

Solution:

Use unicode.IsLower() function to determine if the character is lowercase or not. If not, then push the characters into a slice or form a string with strings.Join() function.

Here you go!

 package main

 import (
 "fmt"
 "regexp"
 "strings"
 "text/scanner"
 "unicode"
 )

 // faster way to get rid delimiters
 // for string without unicode

 func removeDelimString(str string) string {
 // alphanumeric (== [0-9A-Za-z])
 // \s is a white space character
 regExp := regexp.MustCompile(`[^[:alnum:]\s]`)
 return regExp.ReplaceAllString(str, "")
 }

 // get all upper case characters from string
 // to get all lower case characters, just remove the exclamation mark !
 // infront of unicode.IsLower()

 func getUpperCaseChars(str string) []string {

 tokens := removeDelimString(str)

 var result []string

 for _, char := range tokens {

 if !unicode.IsLower(char) && char != ' ' {
 fmt.Println(scanner.TokenString(char))
 result = append(result, scanner.TokenString(char))
 }
 }

 return result
 }

 func main() {
 str := "This a string with some UpperCase Characters."

 temp := getUpperCaseChars(str)

 for k, v := range temp {
 fmt.Println(k, v)
 }

 // form into a UPPERCASE string

 upper := removeDelimString(strings.Join(temp, ""))
 fmt.Println(upper)

 }

Output:

"T"

"U"

"C"

"C"

0 "T"

1 "U"

2 "C"

3 "C"

TUCC

References:

https://www.socketloop.com/tutorials/golang-how-to-join-strings

https://golang.org/pkg/unicode/#IsLower

https://socketloop.com/tutorials/golang-break-string-into-a-slice-of-characters-example