100daysofcode - Day 18
Hello folks, hope you are doing well, and you are learning some amazing things in this amazing tech world. 
In yesterday’s post, we talked about string formatting in Golang. And in today’s post we will define the regular expressions in Golang. How to use them and to do so ? 
What is a regular expression ?
- A regular expression
(shortened as regexorregexp; sometimes referred to as rational expression) is a sequence of characters that specifies a search pattern in text. Usually such patterns are used by string-searching algorithms for “find” or “find and replace” operations on strings, or for input validation.
Application of regular expression ?
-
Simple parsing.
-
The production of syntax highlighting systems.
-
Data Validation.
-
Data Scraping (especially web scraping)
-
Data wrangling.
Example
package main
import (
"fmt"
"regexp"
)
func main() {
match, _ := regexp.MatchString("p([a-z]+)ch", "peach")
fmt.Println(match)
r, _ := regexp.Compile("p([a-z]+)ch")
fmt.Println(r.MatchString("peach"))
fmt.Println(r.FindString("peach punch"))
fmt.Println("idx:", r.FindStringIndex("peach punch"))
fmt.Println(r.FindStringSubmatch("peach punch"))
fmt.Println(r.FindStringSubmatchIndex("peach punch"))
fmt.Println(r.FindAllString("peach punch pinch", -1))
fmt.Println("all:", r.FindAllStringSubmatchIndex(
"peach punch pinch", -1))
fmt.Println(r.FindAllString("peach punch pinch", 2))
fmt.Println(r.Match([]byte("peach")))
r = regexp.MustCompile("p([a-z]+)ch")
fmt.Println("regexp:", r)
fmt.Println(r.ReplaceAllString("a peach", "<fruit>"))
/*
true
true
peach
idx: [0 5]
[peach ea]
[0 5 1 3]
[peach punch pinch]
all: [[0 5 1 3] [6 11 7 9] [12 17 13 15]]
[peach punch]
true
regexp: p([a-z]+)ch
a <fruit>
a PEACH
*/
}