Is Power Of 2

IsPowerOf2 is a function that will take an argument and return true if the number given is a power of 2, otherwise it returns false.

2² = 2 * 2 = 4  
2³ = 2 * 2 * 2 = 8
ect

Functions

This exercice allow the use of the strconv package, that will allow us to convert our argument into an int.

We will use a function called PrintStr that will allow us to print strings (true and false here).

func PrintStr(s string) {
  for i := 0; i < len(s); i++ {
    z01.PrintRune(rune(s[i]))
  }
  z01.PrintRune('\n')
}

IsPowerOf2 step by step

First step

We first need to check if we have only one argument:

if len(os.Args) != 2 {
        return
    }

If not then we just end the program.

Second step

We convert the first argument into an int, to be able to compare it after.

  number, err := strconv.Atoi(os.Args[1])
    if err != nil {
        return
    }

If the error isn't equal to nil, that means that our argument isn't an int, we then end the program.

Third and final step

We loop over the values of powers of 2.
We do that by multiplying i by 2 as incrementation.

// The i inferior or equal to number is very important here
for i := 2; i <= number; i = i * 2 {
    // compare is at any time i is equal to our number
        if i == number {
            PrintStr("true")
            return
        }
    }
  // if we manage to get out of the loop without ending the program, that means our number isn't a power of 2
    PrintStr("false")

If i is equal to our number, then we Print "true" and end the program, otherwise we Print "false".

Full code

package main

import (
    "os"
    "strconv"
)

func IsPowerof2() {
  // first step
    if len(os.Args) != 2 {
        return
    }
  // second step
    number, err := strconv.Atoi(os.Args[1])
    if err != nil {
        return
    }
  // final step
    for i := 2; i <= number; i = i * 2 {
        if i == number {
            PrintStr("true")
            return
        }
    }
    PrintStr("false")
}