How Can I Extract All Strings Enclosed in Curly Braces from a String Using Go's Regexp Package?

Finding String Matches with Regex in Go

This article explores the task of retrieving all matches of a given regular expression against a specified string. We'll examine a sample string and implement a solution using Go's regexp package to capture strings enclosed in curly braces.

Problem Statement

Given a string:

{city}, {state} {zip}

Our goal is to return an array or slice containing all the matches of strings between curly braces.

Solution

To achieve this, we can leverage regular expressions to define the desired pattern. However, there are a few key modifications to make compared to the initial attempt.

First, we remove the regex delimiters ("/") as they are unnecessary in Go. Second, we employ raw string literals (denoted by backticks `) to define the regex pattern. This allows us to use a single backslash () to escape regex metacharacters. Finally, since we don't need to capture the individual values, we can simplify the regex pattern to match strings between curly braces without capturing parentheses.

Here's an updated version of the code:

r := regexp.MustCompile(`{[^{}]*}`)
matches := r.FindAllString("{city}, {state} {zip}", -1)

This code will return an array with the following matches:

["{city}", "{state}", "{zip}"]

Diving Deeper

If we want to extract only the values within curly braces, we can use FindAllStringSubmatch with a slightly modified regex pattern that includes capturing parentheses:

r := regexp.MustCompile(`{([^{}]*)}`)
matches := r.FindAllStringSubmatch("{city}, {state} {zip}", -1)

In this pattern, ([^{}]*) is a capturing group that matches any number of characters other than curly braces. Using FindAllStringSubmatch will return an array of submatches for each match. We can then loop through these submatches to obtain the values within the parentheses.

Regex Details

• { - Literal left curly brace
• ([^{}]*) - Capturing group matching zero or more characters excluding curly braces
• } - Literal right curly brace

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