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is_string

yarco dot w at gmail dot com
03-Sep-2007 01:19


re: php dot net at oui dot jp



<?php

$a = array('0' => 'zero'); // '0'



// is different from



$b = '0'; // '0'

?>



Because when you use array, it will automatically change the key to integer if it could.

So, it output:



>php -r "print var_dump(array_keys(array('0' => '

zero', '1' => 'one')));"

array(2) {

  [0]=>

  int(0)

  [1]=>

  int(1)

}



They are int type, not string.

Dainix Zsigmond
01-Aug-2007 08:44


To php dot net at oui dot jp:

 

It's going to return a string if the variable's value is encased around quotes or apostrophes, period.  Be it a '0' or a '1', it's a string all around.  The index in an array is a little bit of a different story.



Sample coding is below:



<?php

$ar = array('this is a string.', '38', '038', 0382, 3892.283);

$ar2 = array('S1' => 'string.', 'S2' => 'a string.', '3' => 3827, '3.82.' => '2222', '-1' => 'foo');

foreach($ar as $num => $string)

{

    if (is_string($string)) { echo 'Yes. <br />'; } else { echo 'No. <br />'; }

}

print_r($ar);

foreach($ar2 as $num => $string)

{

    if (is_string($num)) { echo 'Yes. <br />'; } else { echo 'No. <br />'; }

}

print_r($ar2);

?>

The first foreach contains a simple if/then statement that checks if the array value is a string or not, which works correctly (Yes, Yes, Yes, No, No).  The second checks if the index identifier is a string.  It returns Yes, Yes, No, and Yes.

 

Printing the array: Array ( [S1] => string. [S2] => a string. [3] => 3827 [3.82] => 2222 [-1] => foo)

The index identifier will be marked as a string if the identifier is not an integer above zero.

php dot net at oui dot jp
06-Jun-2007 06:13


<?php

        // Interesting...



        $arr  = array ('abc','def','ghi');

        $aarr = array ('0' => 'abc','1' => 'def','2' => 'ghi');



        foreach ($arr as $u => $v)

          print is_string($u) ? "Yes\n":"no\n"; // no: ok, index is numeric (0, 1, 2)



        foreach ($aarr as $u => $v)

          print is_string($u) ? "Yes\n":"no\n"; // still no! was expecting Yes!



        if (is_string ('0')) print "'0' is a string\n"; // ...as '0' is a string!

?>

tobias_demuth at web dot de
26-Aug-2005 07:32


Returns true, if the string is empty, too.

djhook at users dot sourceforge dot net
11-Sep-2003 07:20


function is_upper($input) {

    return ($input == strtoupper($input));

}



function is_lower($input) {

    return ($input == strtolower($input));

}



this functions check if a string is all upper/lower case.



input:   string

output: true/false

slicky at newshelix dot com
20-Mar-2001 05:06


Be aware that this function could result into unwanted results if you check single chars in an array.

For instance:

You have a simple string and want to repeat this string evertime it ends.

<p>for ($i=0; $i < strlen($string);$i++){

        if(!is_string($key[$x]))

            $x = 0;

                echo $key[$x];

        $x++;

    }

</p>This will print you out the key, but won't iterate it since $x won't be reset. is_string function will give out true at element in that string, even if it doesn't exist. for instance is_string $key[1000] while your string is just 10chars long.

However this doesn't matter just use $key[$x] == '' instead.

Of course you won't use this to iterate a string, but you might come across something where this get useful, for instance for a en/decrypt engine.

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