Go for loops

Go uses the keyword for to execute loops. In Go doesn’t exist while loops (the keyword while doesn’t exist), we have to use a for to create a while loop.

Go basics

package main

import "fmt"

const MAX = 10

func main() {
  for i := 0; i < MAX; i++ {
        fmt.Printf("i = %d\n", i)
  } 
}

Using range. The range allows getting from an array or slices the index and their value.

package main

import "fmt"

const MAX = 10

func main() {
  arr := [MAX]int{1,2,3,4,5,6,7,8,9,10}
  slc := []float64{2.1, 2.4, 1.5, 4.4, 10.1, 234.1}
  alphabet := "ABCDEFGHIJKLMNOPQRSTUVWXYZ"


  fmt.Println("For Array:")
  for index, value := range arr {
        fmt.Printf("arr[%d] = %v\n", index, value)
  }
  fmt.Println("For Slice:")
  for index, value := range slc {
        fmt.Printf("slc[%d] = %v\n", index, value)
  }

  fmt.Println("For a string (alphabet):")
  for index, c := range alphabet {
        fmt.Printf("%d - %c\n", index, c)
  }
  
}

While looping in Go.

package main

import "fmt"

const MAX = 10

func main() {
 arr := [MAX]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
 i := 0
 for i < MAX {
      fmt.Printf("arr[%d] = %d\n", i, arr[i])
      i++
 }
  i = 0
  for {
      if i >= MAX {
            break
      }
      fmt.Printf("arr[%d] = %d\n", i, arr[i])
      i++
  }
}

Example: Playing with a matrix.

package main

import "fmt"

const MAX = 5

func main() {
 matrix := [MAX][MAX]int{
      {1,0,0,0,0},
      {0,1,0,0,0},
      {0,0,1,0,0},
      {0,0,0,1,0},
      {0,0,0,0,1},
 }
 for i, j := 0, 0; i < MAX && j < MAX; i, j = i+1, j+1 {
        fmt.Println(i, j, matrix[i][j])
 }

}