Go for Loop

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Go for Loop

In Go, the for loop is the only looping construct available. It is highly versatile and can be used to implement traditional loops, condition-based loops, and even infinite loops.

Loops are essential when you need to execute a block of code repeatedly. Each repetition is called an iteration.

Basic Syntax of the for Loop

for initialization; condition; post { // code executed in each iteration }

Components Explained

• Initialization: Sets up the loop variable (executed once at the start).
• Condition: Evaluated before each iteration. If true, the loop continues; if false, it stops.
• Post statement: Updates the loop variable after each iteration.

Note: These components are optional, but the loop must still be logically controlled.

Example 1: Printing Numbers

package main import "fmt" func main() { for i := 1; i <= 5; i++ { fmt.Println("Count:", i) } }

Count: 1 Count: 2 Count: 3 Count: 4 Count: 5

Example 2: Loop with Custom Step

This loop increments by 5 in each iteration.

package main import "fmt" func main() { for i := 0; i <= 50; i += 5 { fmt.Println(i) } }

0 5 10 15 20 25 30 35 40 45 50

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Using continue in a Loop

The continue statement skips the current iteration and moves to the next one.

package main import "fmt" func main() { for i := 1; i <= 6; i++ { if i == 4 { continue } fmt.Println(i) } }

1 2 3 5 6

Using break in a Loop

The break statement immediately terminates the loop.

package main import "fmt" func main() { for i := 1; i <= 6; i++ { if i == 4 { break } fmt.Println(i) } }

1 2 3

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Nested Loops in Go

A loop can exist inside another loop. The inner loop runs completely for each iteration of the outer loop.

package main import "fmt" func main() { colors := []string{"Red", "Blue"} items := []string{"Pen", "Book", "Bag"} for i := 0; i < len(colors); i++ { for j := 0; j < len(items); j++ { fmt.Println(colors[i], items[j]) } } }

Red Pen Red Book Red Bag Blue Pen Blue Book Blue Bag

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The range Keyword in Go

The range keyword simplifies iteration over arrays, slices, and maps. It returns both the index and the value.

Syntax

for index, value := range collection { // code }

Example: Iterating with range

package main import "fmt" func main() { languages := []string{"Go", "Python", "Java"} for index, value := range languages { fmt.Printf("Index: %d, Value: %s\n", index, value) } }

Index: 0, Value: Go Index: 1, Value: Python Index: 2, Value: Java

Ignoring Index or Value

You can use _ (blank identifier) to ignore unwanted values.

Ignore Index:

package main import "fmt" func main() { languages := []string{"Go", "Python", "Java"} for _, value := range languages { fmt.Println(value) } }

Go Python Java

Ignore Value:

package main import "fmt" func main() { languages := []string{"Go", "Python", "Java"} for index := range languages { fmt.Println(index) } }

0 1 2

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