How To: Split while loop with double comparisson into two?

Question

I am writing a program that implements the insertion sort algorithm to sort an array:

 public void insertionSort()
{
    int in, out;

    for (out = 1; out < nElems; out++)     // out is dividing line
    {
        copies++;                       
        long temp = a[out];            // remove marked item
        in = out;                      // start shifts at out
        while (in > 0 && a[in - 1] >= temp) // until one is smaller,
        {
            a[in] = a[in - 1];            // shift item to right
            --in;                       // go left one position
            ++comparissons;             
        }
        a[in] = temp;                  // insert marked item
    }  // end for
}  // end insertionSort(

I am also implementing counters that count how many comparisons are made during the course of the algorithm. in my while loop:

 while (in > 0 && a[in - 1] >= temp) // until one is smaller,
    {
        a[in] = a[in - 1];            // shift item to right
        --in;                       // go left one position
        ++comparissons;             
    }

two comparison are made, that means for those two comparison the 'comparissons' variable is only incremented by one (even though TWO comparisons are actually made).

My question is: how do I break down this while loop with two comparison into two parts so I can increment 'comparissons' each time a comparison is actually made while retaining the same functionality.

Thanks!

JLL

Answer 1

Are you referring to the comparisons in the while condition? If yes, just check those conditions separately

while (in > 0) // until one is smaller,
{
    ++comparissons; 
    if (a[in - 1] >= temp)   ++comparissons;
    else                     break;

    a[in] = a[in - 1];            // shift item to right
    --in;                       // go left one position           
}

Answer 2

Move the comparison into an if inside the while loop.

while (in > 0) {
    // Move the comparison increment here.
    if (a[in -1] >= temp) {
       // The rest of the original while code here.   
    } else {
       break;
    }
}

Or you can do a hack like this and move the comparisons increment into the condition itself.

while (in > 0 && ((a[in-1] >= temp) && (++comparisons > -1))) {
}