Can AnyOne Explain this Code me Please

Question

    $odd= true;
echo ($odd == true) ? '<tr class="odd_row">' : '<tr class="even_row">';
    $odd = !$odd;

Please Can Any One Explain this code?

See also: http://stackoverflow.com/questions/1080247/what-is-the-php-operator-called-and-what-does-it-do — Ja͢ck, Jun 04 '13 at 08:34

Oswald · Accepted Answer · 2013-06-08T08:52:19.670

10

The expression [a] ? [b] : [c] is called ternary operator. It is the same as this function:

function ternary($a, $b, $c) {
  if ($a)
    return $b;
  else
    return $c;
}

except that the arguments to the ternary operator are lazy evaluated (i.e. only one of [b] and [c] is actually executed).

$odd = !$odd toggles the value of $odd between true and false.

The code is probably used inside a loop that prints table rows that alternatingly have classes odd_row and even_row, which can then be styled differently using CSS.

edited Jun 08 '13 at 08:52

answered Jun 04 '13 at 08:31

Oswald

31,254
3
43
68

+1 for explaining "toggles the value of $odd between true and false" – Jun 04 '13 at 08:31
It's not exactly the same as your function, consider `echo $a ? 1 : (print "hello");` vs `ternary($a, 1, (print "hello"));` – Ja͢ck Jun 04 '13 at 08:37
i know that but the main motive for asking is thiat – Samir Paruthi Jun 08 '13 at 08:47

score 3 · Answer 2 · answered Jun 04 '13 at 08:29

3

This means

if ($odd == true){
    echo '<tr class="odd_row">';
}else{
    echo '<tr class="even_row">';
}

and is called ternary operator

Then by $odd = !$odd; the value of this variable is "flipped". I guess it's done to make the next row to be "even".

answered Jun 04 '13 at 08:29

k102

7,861
7
49
69

1

what about `$odd = !$odd;` ? – Jun 04 '13 at 08:30
this is equivalent to : – Asenar Jun 04 '13 at 08:31
@Akam, ok, added the explanation – k102 Jun 04 '13 at 08:33
ya k102 it make next row even act. i didnot understand the mean of $odd = !$odd – Samir Paruthi Jun 08 '13 at 08:47

score 0 · Answer 3 · answered Jun 04 '13 at 08:30

This is setting the $odd variable to boolean value true

$odd= true;

This uses whats called a terniary operator to print out a string. If $odd is true it will print the first bit, if not then the second. As you have set $odd to true immediately before, it will always print the first bit

echo ($odd == true) ? '<tr class="odd_row">' : '<tr class="even_row">';

This sets $odd to ! (not) $odd so reverses the boolean to false $odd = !$odd;

Sorry for the literal explanation, but I wanted to be thorough

Can AnyOne Explain this Code me Please

3 Answers3