Challenge 2 — Solution

Task: Write a program that declares var total int with no value,
prints it (confirming it's 0, not an error), then assigns it 100
using = (not :=) and prints it again.

package main

import "fmt"

func main() {
	var total int
	fmt.Println(total)

	total = 100
	fmt.Println(total)
}


Expected output:

0
100

Notes:
- var total int with no value automatically sets total to 0, the
  zero value for int — there is no error, and no "undefined" stage
  to pass through, unlike a JavaScript let total; which would be
  undefined until assigned.
- total = 100 reassigns the existing variable; using := here instead
  would be a compile error, since total already exists in this
  scope.
- This is the core difference from JavaScript's let: Go variables
  are never in a genuinely empty/unset state.