octalToDec method
Calculate and return the decimal value of this octal integer
Implementation
int octalToDec(){
if(this < 0){
throw "Only positive integers can be converted from octal into dec using this library";
}
String octal = this.toString();
int dec = 0;
for(int n = (octal.length - 1); n >= 0; n--){
int thisPositionLetter = int.parse(octal.substring(n, n + 1));
if(thisPositionLetter < 0 || 7 < thisPositionLetter){
throw "Integer cannot be interpreted as octal. It must be composed of characters that are within the range of 0 - 7.";
}
int thisExponent = (n - (octal.length - 1)).abs();
dec += (thisPositionLetter * pow(8, thisExponent)).toInt();
}
return dec;
}