[Number systems in Swift] #algorythms

ns.swift

func numberToBaseString(number:Int,base:Int) -> String {

    var inner_func:(Int,Int,String) -> String = { (_,_,_) -> String in return "" }
    
    inner_func = { (number:Int,base:Int,result:String) -> String in
        if number < base {
            return String(number) + result
        }else{
            let rem = number % base
            let reducedNumber = (number - rem) / base
            return inner_func(reducedNumber, base, String(rem) + result)
        }
    }
    
    return inner_func(number, base, "")
}

func pow(p:Int,n:Int) -> Int {
    if n == 0 {
        return 1
    }else{
        return p * pow(p,n-1)
    }
}

func baseStringToValue(string:String, base:Int) -> Int {
    
    
    
    var inner_func:(String,Int,Int,Int) -> Int = { (_,_,_,_) -> Int in return 0 }
    
    inner_func = { ( string:String, base, result,power) -> Int in
        if string.isEmpty == true {
            return result
        }else{
            let char = string.getEnd
            
            return inner_func(string.getStringWithoutEnd, base, pow(base, power) * char.toInt()! + result,power+1)
            
            
        }
    }
    
    return inner_func(string,base,0,0)
}


println(numberToBaseString(21, 2)) //> "10101"

println(baseStringToValue(numberToBaseString(21, 2), 2)) //> 21