Loops | Golang basics

Mahdi.Kh

September 21, 2026

We get familiar with loops and learn how loops can be used to repeat a set of statements.

Loops let you run a set of statements repeatedly. There's only one kind of loop, the for loop. Even so, this loop can be used in several different ways.

The Counting Loop

The counting loop has three parts:

Initialization: in this part, a variable is declared and assigned a value. This part runs only once, at the start of the loop.
Condition: the loop's condition is checked before every iteration. If the condition is true, the loop body runs; otherwise, the loop stops.
Post: after every run of the statements inside the loop, this part runs to update the counter variable.

for initialization; condition; post {
    // statements inside the loop
}

For example, the code below shows the numbers from 1 to 50:

package main

import "fmt"

func main() {
	for i := 1; i <= 50; i++ {
		fmt.Println(i)
	}
}

Depending on the situation, each part of the counting loop can be omitted, or moved outside or inside the loop:

package main

import "fmt"

func main() {
	i := 1

	for i <= 50 {
		fmt.Println(i)
		i++
	}
}

The Infinite Loop

If we omit the loop's condition, an infinite loop is created. The code below runs forever, printing the current time to the screen every second:

package main

import (
	"fmt"
	"time"
)

func main() {
	for {
		fmt.Println(time.Now())
		time.Sleep(1 * time.Second)
	}
}

If your program has an infinite loop that uses a lot of system resources (CPU, RAM, GPU), your program might run into a resource-exhaustion error.

Looping Over Collections

Looping over collections is done using the for range construct, which lets us iterate over collection types such as arrays, maps, slices, strings, and channels. This loop is used to access each element of the collection.

The general structure of this loop is as follows:

for index, value := range collection {
    // statements inside the loop
}

index: the current element's index
value: the current element's value
collection: the collection being iterated over

package main

import "fmt"

func main() {
	names := []string{
		"John Doe",
		"Alex Newman",
		"Mahdi Khanzadi",
	}

	for i, name := range names {
		fmt.Printf("index is: %d and value is: %q\n", i, name)
	}
}

// output of running the code above:
// index is: 0 and value is: "John Doe"
// index is: 1 and value is: "Alex Newman"
// index is: 2 and value is: "Mahdi Khanzadi"

#golang #go

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