Labels in GO

Labeled Statements in Go allows us to jump to a label using a break, continue or goto statement.

Labels do not conflict with names of other variables.

	var queries string
	_ = queries

queries:
	for _, q := range query {
		for i, w := range words {
			...
		}
	}

Labeled Break

The labeled break allows us break from any labeled loop.

The labeled break works with a Switch statement as well.

Example

queries:
	for _, q := range query {
		for i, w := range words {
			if strings.ToLower(q) == strings.ToLower(w) {
				fmt.Printf("#%-2d: %q\n", i+1, w)

				break queries
			}
		}
	}
}

Output

#4 : "again"

Labeled Continue

The labeled continue continues from the labeled loop (the parent loop in this case) instead of the nested loop.

Example

queries:
	for _, q := range query {
		for i, w := range words {
			if strings.ToLower(q) == strings.ToLower(w) {
				fmt.Printf("#%-2d: %q\n", i+1, w)

				continue queries
			}
		}
	}
}

Output

#4 : "again"
#5 : "and"

Break from a Switch with Labeled Break

We want to filter out unwanted words from the provided query words so it won't be searched for or appear in the search results.

Example

In the example below, whenever the queried words matches the words in the case clause, the case clause is executed.

queries:
	for _, q := range query {
	search:
		for i, w := range words {
			switch q {
				case "and", "or", "the":
				// break
				break search
			}

			if strings.ToLower(q) == strings.ToLower(w) {
				fmt.Printf("#%-2d: %q\n", i+1, w)

				continue queries
			}
		}
	}
}

Output

Using a normal break only breaks from the switch and continues executing the if statement.

#4 : "again"
#5 : "and"

To fix this, we add a labeled break statement to not only break from the switch but also from the nested loop.

#4 : "again"

Usage

go run main.go again and

where again & and are the arguments/query