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i'm new in php and i have problems with this piece of code

i do not figure out , why 'echo' prints : x ? error 3000

3000 is a key , indeed should be printing "scanner error" ...

what's wrong in my code ? thank you to every one ...

    <?php

// ....................................... sym
class Error
{
 const lexer    =   1000 ;
 const parser   =   2000 ;
 const scanner  =   3000 ;

}

final class err extends Error
{
 public $stringerr = array (
    lexer       =>  "Lexer error" ,
    parser      =>  "Parser error" ,
    scanner     =>  "Scanner error" 
 ) ; 
 public function error ( $x )
 {
    echo "\nx" . " ? " . $stringerr[ $x ] . " error ";


    return $x ;
 }

}


?>


    echo err::error( err::scanner ) ;

output :

   x ? error 3000
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Just put echo $x before this line - echo "\nx" . " .... You will understand what's wrong. – Shukla Jay シ Aug 1 at 16:06
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3 Answers

up vote 2 down vote accepted

If I've understood correctly

err::scanner = 3000

$stringerr[ $x ] == $stringerr[3000]

You would need to do err::error('scanner');

or:

public $stringerr = array (
    1000 => "Lexer error",
    2000 => "Parser error",
    3000 => "Scanner error" 
);

And, $stringerr[ $x ] should be $this->stringerr[$x]

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up vote 2 down vote

Your mistake is using a non-static property, while calling a static function. You can see the php notice about it:

PHP Notice: Undefined variable: stringerr in file.php on line 19

Method 1

You should either define the property as static and apply to it via class name:

<?php
class Error
{
    const lexer    =   1000 ;
    const parser   =   2000 ;
    const scanner  =   3000 ;

}

final class err extends Error
{
    public static $stringerr = array (
        Error::lexer       =>  "Lexer error" ,
        Error::parser      =>  "Parser error" ,
        Error::scanner     =>  "Scanner error"
        ) ;
    public static function error ( $x )
    {
        echo "\nx" . " ? " . err::$stringerr[ $x ] . " error ";
        return $x ;
    }

}

echo err::error( err::scanner ) ;
?>

Prints:

x ? Scanner error error 3000

Mention, that I deliberately defined error function as static.

Method 2

Or define an instance of this class and use $this:

<?php
class Error
{
    const lexer    =   1000 ;
    const parser   =   2000 ;
    const scanner  =   3000 ;

}

final class err extends Error
{
    public $stringerr = array (
        Error::lexer       =>  "Lexer error" ,
        Error::parser      =>  "Parser error" ,
        Error::scanner     =>  "Scanner error"
        ) ;
    public function error ( $x )
    {
        echo "\nx" . " ? " . $this->stringerr[ $x ] . " error ";
        return $x ;
    }

}

$var = new err();
echo $var->error( Error::scanner ) ;
?>

http://www.php.net/manual/en/language.oop5.static.php

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Thank you , works perfectly ! – Claudio Daffra 2 days ago
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up vote 2 down vote

echo is for printing on the screen + in the function you are returning $x that didn't receive any changes.

Try:

return $stringerr[$x];

Instead of:

echo "\nx" . " ? " . $stringerr[ $x ] . " error ";
return $x;
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this won't work – user4035 Aug 1 at 16:13
I believe it's a good hint to start with, I can edit it after I know what is it displaying. – heytools Aug 1 at 16:17
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