Intro to Regular Expressions (Pattern Matching)

In this lesson you will learn the basics of pattern matching with regular expressions in Go so you can check whether text follows a given format. This is for anyone searching for "Go regular expressions how to use".

A regular expression is a special notation that describes the shape of a string. You can specify a pattern such as "three digits, a hyphen, then four digits", check whether text matches it, and pull out the matching part. Go provides the regexp package.

The sample code compiles a phone-number-like pattern with regexp.MustCompile(...) and extracts the matching part with re.FindString(text). As re2.MatchString("12345") shows, the same pattern can also simply answer whether the text matches.

A common stumbling block for beginners is learning what all the symbols mean. It looks like nothing but punctuation at first, but it is a powerful tool that pays off in practice, for example when validating email formats.

In real-world development, learning regular expressions once gives you a skill that transfers to most other programming languages.

📖 Reference code

package main

import (
    "fmt"
    "regexp"
)

func main() {
    text := "Phone: 090-1234-5678"
    re := regexp.MustCompile(`\d{3}-\d{4}-\d{4}`)
    fmt.Println(re.FindString(text))

    re2 := regexp.MustCompile(`^\d+$`)
    fmt.Println(re2.MatchString("12345"))
}

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