is_string

描述

bool is_string ( mixed var )

如果 var 是 string 则返回 TRUE，否则返回 FALSE。

参见 is_bool()、is_int()、is_integer()、is_float()、is_real()、is_object() 和 is_array()。

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tobias_demuth at web dot de
26-Aug-2005 10:32


Returns true, if the string is empty, too.

djhook at users dot sourceforge dot net
12-Sep-2003 10:20


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 09:06


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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