lossy conversion when dividing (long to int)

Question

I am trying to find the middle index in an array (of type long) The problem im solving specifically asks for a long to return, so I cant change the signature I want to find the pivot point, in my quicksort code, but I get an error "possible lossy conversion from long to int" I understand that I may lose some information when dividing, but I want to bypass it here is the code containing the error:

public static long partition(long[] array, long left, long right){
    long i = left, j = right;
    long tmp;
    long pivot = array[(left + right) / 2];  // <-----ERROR HERE  <------

    while(i <= j) {
        while(array[i] < pivot){
        i--;
       }
       while(array[j] > pivot) {
           j--;
       }
       if(i <= j) {
           tmp =array[i];
           array[i] = array[j];
           array[j] = tmp;
           i++;
           j--;
       }
       }
    return i;
}

@lakshman that makes no difference, the 2 would undergo binary numeric promotion to long already. — Andy Turner, Mar 07 '18 at 07:38

Andy Turner · Answer 1 · 2018-03-07T07:45:41.537

3

From JLS Sec 10.4:

Arrays must be indexed by int values

Using long for the left and right parameters (and i and j) is meaningless (because an array can't have that many elements), and will result in a compile-time error. Change them to int.

edited Mar 07 '18 at 07:45

answered Mar 07 '18 at 07:34

Andy Turner

137,514
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162
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score 1 · Accepted Answer · answered Mar 07 '18 at 07:43

1

use "array[index]", this "index" must be int. so

long pivot = array[(int)((left + right) / 2)];

answered Mar 07 '18 at 07:43

Heng Lin

96
6

score -1 · Answer 3 · answered Mar 07 '18 at 08:05

-1

I tried typecasting the long to int like.. long pivot = array[(int) ((left + right) / 2)]; It works for me, can you please elaborate in which scenario you are getting the error "possible lossy conversion from long to int".

answered Mar 07 '18 at 08:05

Manish

31
3

[Please format your code properly](https://stackoverflow.com/editing-help) – Dwhitz Mar 07 '18 at 08:11

lossy conversion when dividing (long to int)

3 Answers3