## Go, conversion, binarytodecimal.go

``````/*
Author: Motasim
GitHub: https://github.com/motasimmakki
Date: 19-Oct-2021
*/

// This algorithm will convert any Binary number(0 or 1) to Decimal number(+ve number).
// https://en.wikipedia.org/wiki/Binary_number
// https://en.wikipedia.org/wiki/Decimal
// Function receives a Binary Number as string and returns the Decimal number as integer.
// Supported Binary number range is 0 to 2^(31-1).

package conversion

// Importing necessary package.
import (
"errors"
"regexp"
)

var isValid = regexp.MustCompile("^[0-1]{1,}\$").MatchString

// BinaryToDecimal() function that will take Binary number as string,
// and return it's Decimal equivalent as integer.
func BinaryToDecimal(binary string) (int, error) {
if !isValid(binary) {
return -1, errors.New("not a valid binary string")
}
if len(binary) > 32 {
return -1, errors.New("binary number must be in range 0 to 2^(31-1)")
}
var result, base int = 0, 1
for i := len(binary) - 1; i >= 0; i-- {
if binary[i] == '1' {
result += base
}
base *= 2
}
return result, nil
}
``````