Bubble Sort，bubblesort_PHP教程

Bubble Sort，bubblesort

8 numbers. Sort as ascend.

1st loop, compare 7 times (for 8 numbers), and found the largest 8.

2nd loop, compare 6 times (for 7 numbers), and found the largest 7.

. . .

1, 7, 8

2, 6, 7

3, 5, 6

4, 4, 5

5, 3, 4

6, 2, 3

7, 1, 2

In conclusion: For sorting 8 numbers, we need an outer loop of 7 times, each time for finding a largest number; and an inner loop from comparing 7 times to comparing 1 time (as in the center column).

Implementation in PHP:

 1 php
 2 /* bubble sort: 
 3     1. operate directly on the input array (&), not on a copy
 4     2. sort as ascend
 5 
 6     a is array
 7     m is length of a
 8     n is times of outer loop, n-i is times of comparing for each outer loop
 9     i/j is for-loop counter
10     w is for value swap
11 */
12 function sortBubble(&$a){
13     $m = count($a);
14     $n = $m - 1;
15     for($i=0; $i$n