string_to_snakecase.go

import (
  "fmt"
  "strings"
  "regexp"
)


func main() {
   snakeCase := ConvertToSnakeCase("ILikeProgrammingINGo123")
   fmt.Println("String in snake case : ", snakeCase)
}


func ConvertToSnakeCase(input string) string {
  var matchChars = regexp.MustCompile("(.)([A-Z][a-z]+)")
  var matchAlpha = regexp.MustCompile("([a-z0-9])([A-Z])")
  
  snake := matchChars.ReplaceAllString(input, "${1}_${2}")
  snake = matchAlpha.ReplaceAllString(snake, "${1}_${2}")
  return strings.ToLower(snake)
}


output:
String in snake case :  i_like_programming_in_go123