Conversion from binary to octal in golang

Go program for Conversion from binary to octal. Here mentioned other language solution.

package main
import "strconv"
import "fmt"

//  go lang program for
//  Convert Binary number into Octal number

// Convert decimal number into octal
func octal( number  int)int {
    var  result  int = 0;
    var  multiplier  int = 1;
    var  remainder  int = 0;
    for(number != 0) {
        remainder = number % 8;
        result = (remainder * multiplier) + result;
        multiplier *= 10;
        number = number / 8;
    }
    return result;
}
func binaryToOctal( num  string) {
    if (len(num) == 0) {
        // When empty binary number
        return;
    }
    // Some useful variable
    var  flag  bool = false;
    var  decimalNo  int = 0;
    var  counter  int = 0;
    var  index  int = len(num) - 1;
    // We Assume that given binary number is valid
    // Here - indicates negative binary number
    // First convert binary to decimal
    // Example = 10111 => 23
    for(index >= 0) {
        if (num[index] == '1') {
            decimalNo += (1 << counter);
        } else
            if (num[index] != '0') {
                if (index == 0 && num[index] == '-') {
                    // When get negative number
                    flag = true;
                } else {
                    // Not a valid binary number
                    return;
                }
            }
        counter += 1;
        index -= 1;
    }
    // When given number is 
    var  output  int = octal(decimalNo);
    if (flag == true) {
        output = -output;
    }
    // Display given number
    fmt.Print("Binary : " + num);
    // Display result
    fmt.Println(" Octal : " + strconv.Itoa(output));
}

func main() {
    
    // Test Case
    binaryToOctal("1111");
    binaryToOctal("10111");
    binaryToOctal("101011");
    binaryToOctal("11011");
    binaryToOctal("-1000110");
 
 }

Output

Binary : 1111 Octal : 17
Binary : 10111 Octal : 27
Binary : 101011 Octal : 53
Binary : 11011 Octal : 33
Binary : -1000110 Octal : -106