translation of the exercise: There is a code snippet in PHP. After the loop is over, the variable a gets value
CodePudding user response：
$a starts out as 0 and $i as 10.
The code inside the while loop will run as long as the expression inside the () is true. In PHP, any number that isn't 0 is considered true.
Each time the loop runs (or as we say, each "iteration of the loop", two things happen:
$ais set to$a 2. In other words, $a is now whatever it was before, plus 2.$iis "decremented" by 1. In other words, $i is now whatever it was before, minus 1.
Here are the values of each variable at the end of each iteration:
| Iteration | Value of $a | Value of $i |
|---|---|---|
| 1 | 0 2 = 2 | 10 - 1 = 9 |
| 2 | 2 2 = 4 | 9 - 1 = 8 |
| 3 | 4 2 = 6 | 8 - 1 = 7 |
| 4 | 6 2 = 8 | 7 - 1 = 6 |
| 5 | 8 2 = 10 | 6 - 1 = 5 |
| 6 | 10 2 = 12 | 5 - 1 = 4 |
| 7 | 12 2 = 14 | 4 - 1 = 3 |
| 8 | 14 2 = 16 | 3 - 1 = 2 |
| 9 | 16 2 = 18 | 2 - 1 = 1 |
| 10 | 18 2 = 20 | 1 - 1 = 0 |
Since $i is now 0, the expression in the () is considered false, so the loop stops, and the value of $a is 20.