从数组java中将数字字符串相加

Question

I have a project to take a string of an unset amount of numbers together. In the project you have to convert the string to an array of numbers. Then start at the end of the array and add them together. So I guess I am asking is the best way to go about this. My teacher said use divisor and modulus to get the carry over, but that is all he really gave us I have the Int array set set up just cannot get the result to add up right.

public class FunctionLibrary { public static String performAddition(String sNumber1, String sNumber2) { int length = 0;

if (sNumber1.length() > sNumber2.length())
{
    length = sNumber1.length()-1;
}
else
{
    length = sNumber2.length()-1;
}

int[] input1 = new int[length];
int[] input2 = new int[length];
int[] result = new int[length+1];
String resultS = "";

for (int i = length; i > 0; i--)
{
    input1[i] = Character.getNumericValue(sNumber1.charAt(i));
}

for (int i = length; i > 0; i--)
{
    input2[i] = Character.getNumericValue(sNumber2.charAt(i));
}

for (int i = length; i > 0; i--)
{
    int temp = 0;
    int divid = 0;
    int modulas = 0;
    int answer = 0;
    temp = input1[i] +  input2[i];
    divid = temp/10;
    modulas = temp%10;

    input1[i+1] += modulas;

    answer = divid;

    result[i] = answer;
}

for (int i = 0; i <= length; i++)
{
    resultS += Integer.toString(result[i]);
}

return resultS;

} }

No errors as of this edit but no result coming back.

This is what I have so far but it just does not want to work right. Any help would be appreciated.

Answer 1

for (int i = length; i >= 0; i--) {

 int temp = 0; int divid = 0; int modulas = 0; int answer = 0; temp = input1[i] + input2[i]; divid = temp/10; modulas = temp%10;

First of all, why not merge lines? Second of all, what has division to do with addition?

Because you have to carry numbers to the next; you will need a variable that's outside the for loop. Since you add two single-digit numbers, the highest you can get is 18, so you either;

• get a single-digit you give back, or;

• get 10 + a single-digit you give back

So inside the for-loop; you test if the temp is single digit or not:

boolean carryOne = false;

for (int i = length; i >= 0; i--) {

 int answer = 0; int temp = input1[i] + input2[i]; if(carryOne) { temp++; carryOne = false; } if(temp >= 10) { // two digits: answer = (temp - 10); // you give the left digit back, carryOne = true; // and carry the ten } else answer = temp; // single digit

The biggest process of learning to code, is getting the mindset