integer comparison incorrect or not comparing

Question

I have an array as such:

int array[] = { 1,3,2,5,4,7,6,9,8,10 };

When I try to step through the array and compare the numbers none of them trigger the if condition thereby triggering the swap:

for( int i=0; i<9; i++)
{
    if (array[i] > array[i++])
    {
    cout << "Swapping" << array[i] << " " << array[i++]<< endl;
    int temp = 0;
    temp = array[i];
    array[i] = array[i++];
    array[i++] = temp;
    temp = 0;
}

}

Is there some detail of comparing integers that I am missing? Are they treated differently because they are in an array?

Answer 1

i++ means "return i and set i = i + 1 ". So each time you're using i++ you are increasing i by one which ruins the loop. use i+1 instead.

Answer 2

i++ is a post-increment, and returns the previous value.

 if (array[i] > array[i+1])

Right now, you're comparing array[i] with itself.

You also need the following:

temp = array[i];
array[i] = array[i+1];
array[i+1] = temp;

Answer 3

You're incrementing your i too many times. Change your if statement to:

if ( array[i] > array[ i + 1 ] )

and fix all the other increments likewise apart from the one in your for loop.

Answer 4

The expressions:

array[i] < array[i++]

and

array[i] = array[i++]

is undefined behavior, so anything can happen. (As others have pointed out, it's probably not what you want anyway. As written, you're incrementing i 5 times each time you go through the loop.)

Answer 5

You should use the following code:-

for( int i=0; i<9; i++)
{
    if (array[i] > array[i+1])
    {
     cout << "Swapping" << array[i] << " " << array[i+1]<< endl;
     int temp = 0;
     temp = array[i];
     array[i] = array[i+1];
     array[i+1] = temp;
    temp = 0;
    }
}

The statement: if (array[i] > array[i++]) is equivalent to if (array[i] > array[i]) which doesn't make sense.