Go while Loop

In Go, we use the while loop to execute a block of code until a certain condition is met.

Unlike other programming languages, Go doesn't have a dedicated keyword for a while loop. However, we can use the for loop to perform the functionality of a while loop.

Syntax of Go while loop

for condition {
  // code block
}

Here, the loop evaluates the condition. If the condition is:

• true - statements inside the loop are executed and condition is evaluated again
• false - the loop terminates

Flowchart of while loop in Go

Example: Go while loop

// Program to print numbers between 1 and 5

package main
import ("fmt")

func main() {
  number := 1

  for number <= 5 {
    fmt.Println(number)
    number++
  }
}

Output

1
2
3
4
5

Here, we have initialized the number to 1.

1. During the first iteration, the condition number <= 5 is true. Hence, 1 is printed on the screen. Now, the value of number is increased to 2.
2. Again the test condition, number <= 5 is true. Hence, 2 is also printed on the screen and the value of number is increased to 3.
3. This process continues until number becomes 6. Then, the condition number <= 5 will be false and the loop terminates.

Create multiplication table using while loop

// Program to create a multiplication table of 5 using while loop

package main
import ("fmt")

func main() {
  multiplier := 1

  // run while loop for 10 times
  for multiplier <= 10 {

    // find the product
    product := 5 * multiplier

    // print the multiplication table in format 5 * 1 = 5
    fmt.Printf("5 * %d = %d\n", multiplier, product)
    multiplier++
  }

}

Output

5 * 1 = 5
5 * 2 = 10
5 * 3 = 15
5 * 4 = 20
5 * 5 = 25
5 * 6 = 30
5 * 7 = 35
5 * 8 = 40
5 * 9 = 45
5 * 10 = 50

Here, we have initialized the multiplier := 1. In each iteration, the value of the multiplier gets incremented by 1 until multiplier <= 10.

Go do...while Loop

In Go, we can use the same for loop to provide the functionality of a do while loop. For example,

// Program to print number from 1 to 5

package main
import "fmt"

func main(){
  number := 1

  // loop that runs infinitely
  for {

    // condition to terminate the loop
    if number > 5 {
      break;
    }

    fmt.Printf("%d\n", number);
    number ++

  }
}

Output

1
2
3
4
5

Notice the if statement inside the for loop.

if number > 5 {
  break;
}

This statement acts as the while clause inside a do...while loop and is used to terminate the loop.