how create loop php

1for (initialization; condition; increment){
2   code to be executed;
3}
4//Example
5<?php
6    $a = 0;
7    $b = 0;
8 for( $i = 0; $i<5; $i++ )
9    {
10        $a += 10;
11        $b += 5;
12    }    
13echo ("At the end of the loop a = $a and b = $b" );
14?>
15//.......................................//
16  do {
17   code to be executed;
18}
19while (condition);
20//Example
21<?php
22     $i = 0;
23    $num = 0;
24         
25  do {
26       $i++;
27     }
28         
29  while( $i < 10 );
30 echo ("Loop stopped at i = $i" );
31?>