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The Power of For

Go takes a unique approach to loops: there’s only one looping keyword - for. This single construct handles all looping scenarios, from traditional counted loops to while-style iterations.
One Loop to Rule Them All: Go uses the for keyword for all loop types. There is no while or do-while - for does it all.

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Loop Types in Go

Go’s for loop can be used in three main ways:

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1. While-Style Loop

A for loop with only a condition acts like a while loop: 
i := 0
for i < 5 {
    println(i)
    i++
}

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2. Traditional For Loop

The classic three-component loop with initialization, condition, and post statement: 
for j := 0; j < 5; j++ {
    println(j)
}

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3. Range Loop

Iterate over a sequence using the range keyword: 
for k := range 3 {
    fmt.Println(k)
}

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Complete Example

Here’s a complete program demonstrating all three loop types: 
package main

import "fmt"

// there is no while only for

func main() {
    // while loop
    i := 0
    for i < 5 {
        println(i)
        i++
    }

    // for loop
    for j := 0; j < 5; j++ {
        println(j)
    }

    // range loop
    for k := range 3 {
        fmt.Println(k)
    }
}

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Understanding Each Loop Type

1

While-style loops

Use when you need to loop based on a condition, without knowing the iteration count upfront
i := 0
for i < 5 {
    println(i)
    i++
}
This is equivalent to while (i < 5) in other languages.
2

Traditional for loops

Use when you know exactly how many iterations you need
for j := 0; j < 5; j++ {
    println(j)
}
The structure is: for initialization; condition; post { }
3

Range loops

Use to iterate over sequences, collections, or numeric ranges
for k := range 3 {
    fmt.Println(k)  // prints 0, 1, 2
}
Range loops are especially powerful with arrays, slices, and maps.

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Why No While Loop?

Go’s designers chose to use a single for keyword for simplicity and consistency. Instead of learning multiple loop keywords, you master one flexible construct.
The for loop in Go is versatile enough to handle:
  • While loops: for i < 5 { ... }
  • Infinite loops: for { ... }
  • Traditional for: for i := 0; i < 5; i++ { ... }
  • Foreach-style: for i := range x { ... }

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Loop Control

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Breaking Out of Loops

Use break to exit a loop early: 
for i := 0; i < 10; i++ {
    if i == 5 {
        break  // exits the loop when i equals 5
    }
    println(i)
}

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Skipping Iterations

Use continue to skip to the next iteration: 
for i := 0; i < 5; i++ {
    if i == 2 {
        continue  // skips printing 2
    }
    println(i)
}

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Infinite Loops

Create an infinite loop with just for: 
for {
    // runs forever until break or return
    if someCondition {
        break
    }
}
Be careful with infinite loops! Always ensure there’s a way to exit, either through break, return, or an external signal.

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Common Patterns

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Counting Up

for i := 1; i <= 10; i++ {
    fmt.Println(i)
}

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Counting Down

for i := 10; i >= 1; i-- {
    fmt.Println(i)
}

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Iterating with Step

for i := 0; i < 10; i += 2 {
    fmt.Println(i)  // prints 0, 2, 4, 6, 8
}

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Next Steps

With control flow mastered, you’re ready to work with collections like arrays and slices, where you’ll use these loops extensively with the range keyword.

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