Why while loop is showing 2 different outputs?

Question

Why is while loop showing 2 different outputs?

      $a=1;
    while ($a++ <4) {
       echo $a. "<br>";

    }  // output is 2 3 4 but (4 is not less than 4 )



      $a=1;
    while (++$a <4) {
       echo $a. "<br>";

    }       // output is  2 3

Please, can someone explain me the difference in detail? in $a++ it is showing output 2 3 4 but 4 is not less than 4 in while condition then why it is showing 4 which is not satisfying the condition?

your answer is here all explain why this work like : https://stackoverflow.com/a/9901848/7657988 — Nishit Manjarawala, Mar 10 '18 at 07:34
Possible duplicate of [What's the difference between ++$i and $i++ in PHP?](https://stackoverflow.com/questions/1756015/whats-the-difference-between-i-and-i-in-php) — TarangP, Mar 10 '18 at 07:34
Read effect of pre-increment and post-increment operators here: http://php.net/manual/en/language.operators.increment.php — B. Desai, Mar 10 '18 at 07:34
@Rohan It is effect of pre-increment and post-increment operators. — Mohit Kumar, Mar 10 '18 at 07:41

score 0 · Answer 1 · edited Mar 17 '18 at 00:10

0

++$a increases value before execute
$a++ increases value after execute

edited Mar 17 '18 at 00:10

Ronan Boiteau

9,608
6
34
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answered Mar 10 '18 at 08:05

Rafeeq Mohamed

182
1
4
14

score 0 · Accepted Answer · answered Mar 10 '18 at 08:06

0

In simple anwer, when ++ use as suffix, php first execute while, then add 1 number to $a, Meaning in first while your start $i is 1.

And when ++ use as prefix, php first add 1 number to $a, then execute while, Meaning last while your start is 2.

This is same your code:

$a=1;
while ($a++ <4) {
   echo $a. "<br>";

}  // output is 2 3 4 but (4 is not less than 4 )
$a++;



$a=1;
$a++;
while (++$a <4) {
   echo $a. "<br>";

}       // output is  2 3

answered Mar 10 '18 at 08:06

Hamid Abbasi

346
2
14

It means that first $a++ store 1 and then increments to 2 after while loop execute and echo value 2 – Rohan Mahajan Mar 10 '18 at 08:14

Why while loop is showing 2 different outputs?

2 Answers2