The regexp Package

package main
import (
  "fmt"
  "regexp"
  "strconv"
)
func main() {
  searchIn := "John: 2578.34 William: 4567.23 Steve: 5632.18" // string to search
  pat := "[0-9]+.[0-9]+" // pattern search in searchIn
  f := func (s string) string {
    v, _ := strconv.ParseFloat(s, 32)
    return strconv.FormatFloat(v * 2, 'f', 2, 32)
  }
  if ok, _ := regexp.Match(pat, []byte(searchIn)); ok {
    fmt.Println("Match found!")
  }
  re, _ := regexp.Compile(pat)
  str := re.ReplaceAllString(searchIn, "##.#") // replace pat with "##.#"
  fmt.Println(str)
  // using a function
  str2 := re.ReplaceAllStringFunc(searchIn, f)
  fmt.Println(str2)
}