Please help with the best way of adding together numbers like this ..

Question

Hey.
What's the best way with J2ME to acheive this .. I have an integer, let's the it's value is "123456" and what I wanna do is to add them together this way: 1 + 2 +3 + 4 + 5 + 6. How would I do that? Thanks in advance!

Answer 1

My solution should keep going until you have all the digits added, regardless of the number of digits. Because it divides the number by 10 each time through the loop, it'll stop when you have divided it enough to reach 0 using integer division. So if your number only has 1 digit, the loop will only run 1 time, and if you have a 20 digit long value (change types to long), it'll run 20 times.
If you want all of the digits added up, this'll do it. If you want the first n digits, and don't know how many digits(m) there are it's going to need a different approach. If you know how many digits long the number is....
int number = 12345678;
int totalLength = 8;
int usefulDigits = 3;
int firstDigit = totalLength - usefulDigits;
for(int i=0; i < totalLength; i++){
    if(i >= firstDigit){
        sum += a % 10;
    a = a / 10;
}This requires you to figure out how many digits are in the number ahead of time. I'm not sure about the fastest way to do this, but I'd likely do it with a series of if() statements that look for the number of digits in a binary-search style...
//pseudo code...
if(num >= 10000){
    //at least 5 digits...
    if(num >= 1000000){
        //at least 7 digits...
        ... fill it in ...
    }else{
        //5 or 6 digits...
        if(num >= 100000){
            //six digits...
            return 6;
        }else{
            //5 digits
            return 5;
}else{
    .... just like above...
}Edited by: hooble on Jan 28, 2008 10:07 AM