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The Way to Go

Use of Labels - goto

Explore how to use labels and the goto keyword in Go for controlling program flow, especially within nested loops. Understand when to use continue and break with labels, avoid pitfalls like infinite loops and spaghetti code, and improve your control structures for clearer code.

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Introduction #

A label is a sequence of characters that identifies a location within a code. A code line which starts with a for, switch, or select statements can be preceded with a label of the form:

IDENTIFIER:
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This is the first word ending with a colon : and preceding the code (gofmt puts it on the preceding line).

Use of labels in Go

Let’s look at an example of using a label in Go:

Go (1.6.2)
package main
import "fmt"
func main() {
    LABEL1:                           // adding a label for location
    for i := 0; i <= 5; i++ {         // outer loop
        for j := 0; j <= 5; j++ {         // inner loop
            if j == 4 {
                continue LABEL1                   // jump to the label
            }
            fmt.Printf("i is: %d, and j is: %d\n", i, j)
        }
    }
}

As you can see, we made a label LABEL1 at line 5. At line 6, we made an outer loop: for i := 0; i <= 5; i++ that will iterate 5 times. At line 7, we made an inner loop: for j := 0; j <= 5; j++ that will iterate 5 times for each i. You may have noticed that we added continue LABEL1 at line 9. The execution will jump to the label ...