Calculating the sum of all odd array indexes

Question

I want to calculate the sum of all odd array indexes, but I\'m having some trouble finding the right way to do it.

Here\'s my code so far:

    String id         


        

Answer 1

Just edited your code:

String id = "9506265088085";
int[] intArray = new int[id.length()];
int sum = 0;

for (int i = 0; i < intArray.length; i++) {

    if (i%2!=0)
    {
        sum += Integer.parseInt(String.valueOf(id.charAt(i));

    }} 

    System.out.println(sum);

Answer 2

You are looping only from i=0 to i=5

Answer 3

There is no Index 13 in this array as in Java index starts from 0. A solution to calculating the sum of all odd array indexes with Java 8 is:

    String id = "9506265088085";
    String[] strArray = id.split("");

    int sum = IntStream.range(0, strArray.length)
            .filter(idx -> idx % 2 == 1)
            .map(idx -> Integer.parseInt(strArray[idx]))
            .sum();

    System.out.println(sum);

Answer 4

String id = "9506265088085";
int[] intArray = new int[strArray.length];
int sum = 0;

for (int i = 1; i < id.length(); i+=2) {
        sum += Integer.parseInt(String.valueOf(id.charAt(i)));
    } 

    System.out.println(sum);

Answer 5

The other answer is right, you are only looping to 5. However, you're making this overly complicated; there's a neat trick you can use to avoid Integer.parseInt() and String.valueOf():

int sum = 0;

for (int i = 1; i < id.length(); i += 2) {
    sum += (id.charAt(i) - '0');
}

Also note that instead of checking i%2 repeatedly, you can simply add 2 to the loop control variable at the end of each iteration (and let it start at 1 so you hit only the odd indices).