Generate All Boolean Array Combinations

Mon, 04 May 2020 05:54:59 +0200

While writing Go tests for goxplorer, I wanted to test all boolean flags combinations without having to cascade for loops.
This first method came to mind:

package main

import (
	"fmt"
)

func stob(bf []bool, s string) {
	for i, b := range s {
		if b == '0' {
			bf[i] = false
		} else {
			bf[i] = true
		}
	}
}

func main() {
	bf := []bool{false, false, false, false, false}

	for i := 0; i < 32; i++ {
		b := fmt.Sprintf("%b", i)
		stob(bf, b)
		fmt.Println(bf)
	}
}

Because the fastest way of generating every possible combination of 5 bits is to count from 0 to 31, i.e. 2^5, i.e. 32. The second trick here is to use fmt.Sprintf("%b") to generate a string representing the binary value.
It works, but I found the idea of using strings too heavy for a “binary” task.
A friend came to me with a barbaric bits field solution I found way too smart / complicated :), so I thought about another option but also using bits field, and thought about the following: how to tell if a field is a 1? One of the many options is the or binary operator; indeed, if a field is 0 and is “or’ed” with a 1, its value will become 1, if the initial value is 1, it will not change. Remember or truth table?

Algorithmics on iMil.net

Generate All Boolean Array Combinations