CODEWITHSUNDEEP
phpfor-loopoperatorsequals
jk jk
jk jk

Reputation: 1075

php using two equal operator

my original code is:

$name = '';

for($i = 0;$i < 10; $i++) {
    $name .= '1';
}

i edited to following code

for($name = $i = '';$i < 10; $i++) {
    $name .= '1';
}

echo $name;

output is 1111111111

var_dump: string(10) "1111111111"

is this valid code?

can i use multiple equal operator like $name = $i = ''?

and why i set it to '' empty string

but for{} function can successfully looping 1?

$i isn't must be integer to $i++?

Upvotes: 1

Views: 215

Answers (3)

Brian
Brian

Reputation: 5028

If you try this,

$i = '';
$i++;
echo $i;

you can see that the output = 1.

Since you need to compare $i with 10 in your code, php dynamically converts i to integer and assigns 0.

Remember that php is dynamically typed language.

Upvotes: 0

Barmar
Barmar

Reputation: 780724

The reason this works is because + automatically converts its arguments to numbers, and any string that doesn't begin with a number converts to 0.

But this code is really confusing, and I wouldn't recommend it. If you want to initialize $name in the loop, you can write:

for ($name = '', $i = 0; $i < 10; $i++) {
    $name .= '1';
}

But I don't see why you think this is necessary. Your original code is the way most PHP programmers would write it. There's no gain from putting the string initialization in the for header.

Conversely, if you want to get really compact, you can write:

for ($name = $i = ''; $name .= '1', ++$i < 10; );

I'm not endorsing that last code, it's just a demonstration of the power of the comma operator and pre-increment.

Upvotes: 2

hek2mgl
hek2mgl

Reputation: 157947

can i use multiple equal operator like $name = $i = ''

Yes this is possible as you see

and why i set it to '' empty string

The loose typing system of php will convert an empty string in an integer operation into 0

Upvotes: 1

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