PHP Australia Conference 2015

strval

(PHP 4, PHP 5)

strvalRestituisce il valore di una variabile interpretato come stringa

Descrizione

string strval ( mixed $var )

Restituisce il valore di una variabile interpretato come stringa. Vedere la documentazione su string per più informazioni sulla conversione in stringa.

Questa funzione non effettua formattazioni sul valore restituito. Se si sta cercando un modo per formattare un valore numerico come una stringa, dare un'occhiata a sprintf() o a number_format().

Elenco dei parametri

var

La variable che viene convertita in una string.

var può essere qualsiasi tipo scalare o un oggetto che implementa il metodo __toString(). Non si può utilizzare strval() su array o su oggetti che non implementano il metodo __toString().

Valori restituiti

Il valore string di var.

Esempi

Example #1 Esempio di strval() utilizzando il metodo magico __toString() di PHP 5.

<?php
class StrValTest
{
    public function 
__toString()
    {
        return 
__CLASS__;
    }
}

// Prints 'StrValTest'
echo strval(new StrValTest);
?>

Vedere anche:

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User Contributed Notes 8 notes

up
3
Hayley Watson
7 years ago
As of PHP 5.2, strval() will return the string value of an object, calling its __toString() method to determine what that value is.
up
2
Steve Ball
9 years ago
It seems that one is being treated as an unsigned large int (32 bit), and the other as a signed large int (which has rolled over/under).

2326201276 - (-1968766020) =  4294967296.
up
2
portos_ze_retour at hotmail dot fr
8 years ago
In complement to Tom Nicholson's contribution, here is the french version (actually it's possible to change the language, but you should check the syntax ;) )

function int_to_words($x) {
   global $nwords;

   if(!is_numeric($x))
     $w = '#';
   else if(fmod($x, 1) != 0)
     $w = '#';
   else {
     if($x < 0) {
         $w = $nwords['minus'].' ';
         $x = -$x;
     } else
         $w = '';
     // ... now $x is a non-negative integer.

     if($x < 21)  // 0 to 20
         $w .= $nwords[$x];
     else if($x < 100) {  // 21 to 99
         $w .= $nwords[10 * floor($x/10)];
         $r = fmod($x, 10);
         if($r > 0)
           $w .= '-'. $nwords[$r];
     } else if($x < 1000) {  // 100 to 999
         $w .= $nwords[floor($x/100)] .' '.$nwords['hundred'];
         $r = fmod($x, 100);
         if($r > 0)
           $w .= ' '.$nwords['separator'].' '. int_to_words($r);
     } else if($x < 1000000) {  // 1000 to 999999
         $w .= int_to_words(floor($x/1000)) .' '.$nwords['thousand'];
         $r = fmod($x, 1000);
         if($r > 0) {
           $w .= ' ';
           if($r < 100)
               $w .= $nwords['separator'].' ';
           $w .= int_to_words($r);

         }
     } else {    //  millions
         $w .= int_to_words(floor($x/1000000)) .' '.$nwords['million'];
         $r = fmod($x, 1000000);
         if($r > 0) {
           $w .= ' ';
           if($r < 100)
               $word .= $nwords['separator'].' ';
           $w .= int_to_words($r);
         }
     }
   }
   return $w;
}

// Usage in English
$nwords = array( "zero", "one", "two", "three", "four", "five", "six", "seven",
                   "eight", "nine", "ten", "eleven", "twelve", "thirteen",
                   "fourteen", "fifteen", "sixteen", "seventeen", "eighteen",
                   "nineteen", "twenty", 30 => "thirty", 40 => "forty",
                   50 => "fifty", 60 => "sixty", 70 => "seventy", 80 => "eighty",
                   90 => "ninety" , "hundred" => "hundred", "thousand"=> "thousand", "million"=>"million",
                   "separator"=>"and", "minus"=>"minus");

echo 'There are currently '. int_to_words(-120223456) . ' members logged on.<br>';

//Utilisation en Francais
$nwords = array( "zéro", "un", "deux", "trois", "quatre", "cinq", "six", "sept",
                   "huit", "neuf", "dix", "onze", "douze", "treize",
                   "quatorze", "quinze", "seize", "dix-sept", "dix-huit",
                   "dix-neuf", "vingt", 30 => "trente", 40 => "quarante",
                   50 => "cinquante", 60 => "soixante", 70 => "soixante-dix", 80 => "quatre-vingt",
                   90 => "quatre-vingt-dix" , "hundred" => "cent", "thousand"=> "mille", "million"=>"million",
                   "separator"=>"", "minus"=>"moins");

echo 'Il y a actuellement '. int_to_words(-120223456) . ' membres connectés.<br>';
up
2
kendsnyder+phpnet at gmail dot com
7 years ago
The only way to convert a large float to a string is to use printf('%0.0f',$float); instead of strval($float); (php 5.1.4).

// strval() will lose digits around pow(2,45);
echo pow(2,50); // 1.1258999068426E+015
echo (string)pow(2,50); // 1.1258999068426E+015
echo strval(pow(2,50)); // 1.1258999068426E+015

// full conversion
printf('%0.0f',pow(2,50)); // 112589906846624
echo sprintf('%0.0f',pow(2,50)); // 112589906846624
up
1
php at ianco dot co dot uk
8 years ago
I can't help being surprised that

(string)"0" == (string)"0.00"

evaluates to true. It's the same with strval and single quotes.
=== avoids it.

Why does it matter? One of my suppliers, unbelievably, uses 0 to mean standard discount and 0.00 to mean no discount in their stock files.
up
0
anthony dot parsons at manx dot net
8 years ago
If you have to compare object variables like this be careful not to make a typo, or you could end up calling __set() -
<?php
/* Does what you'd expect it to */
if ( $user->password == $user2->password )

/* Doesn't */
if ( $user->password = $user2->password )
?>

To avoid that ever happening, do it like this:
<?php
if ( strval($user->password) == $user2->password )
?>
up
-1
NyctoFixer at gmail dot com
7 years ago
As of PHP 5.1.4 (I have not tested it in later versions), the strval function does not attempt to invoke the __toString method when it encounters an object. This simple wrapper function will handle this circumstance for you:

<?

/**
* Returns the string value of a variable
*
* This differs from strval in that it invokes __toString if an object is given
* and the object has that method
*/
function stringVal ($value)
{
   
// We use get_class_methods instead of method_exists to ensure that __toString is a public method
   
if (is_object($value) && in_array("__toString", get_class_methods($value)))
        return
strval($value->__toString());
    else
        return
strval($value);
}

?>
up
-1
Tom Nicholson
10 years ago
If you want to convert an integer into an English word string, eg. 29 -> twenty-nine, then here's a function to do it.

Note on use of fmod()
  I used the floating point fmod() in preference to the % operator, because % converts the operands to int, corrupting values outside of the range [-2147483648, 2147483647]

I haven't bothered with "billion" because the word means 10e9 or 10e12 depending who you ask.

The function returns '#' if the argument does not represent a whole number.

<?php
$nwords
= array( "zero", "one", "two", "three", "four", "five", "six", "seven",
                  
"eight", "nine", "ten", "eleven", "twelve", "thirteen",
                  
"fourteen", "fifteen", "sixteen", "seventeen", "eighteen",
                  
"nineteen", "twenty", 30 => "thirty", 40 => "forty",
                  
50 => "fifty", 60 => "sixty", 70 => "seventy", 80 => "eighty",
                  
90 => "ninety" );

function
int_to_words($x) {
   global
$nwords;

   if(!
is_numeric($x))
     
$w = '#';
   else if(
fmod($x, 1) != 0)
     
$w = '#';
   else {
      if(
$x < 0) {
        
$w = 'minus ';
        
$x = -$x;
      } else
        
$w = '';
     
// ... now $x is a non-negative integer.

     
if($x < 21)   // 0 to 20
        
$w .= $nwords[$x];
      else if(
$x < 100) {   // 21 to 99
        
$w .= $nwords[10 * floor($x/10)];
        
$r = fmod($x, 10);
         if(
$r > 0)
           
$w .= '-'. $nwords[$r];
      } else if(
$x < 1000) {   // 100 to 999
        
$w .= $nwords[floor($x/100)] .' hundred';
        
$r = fmod($x, 100);
         if(
$r > 0)
           
$w .= ' and '. int_to_words($r);
      } else if(
$x < 1000000) {   // 1000 to 999999
        
$w .= int_to_words(floor($x/1000)) .' thousand';
        
$r = fmod($x, 1000);
         if(
$r > 0) {
           
$w .= ' ';
            if(
$r < 100)
              
$w .= 'and ';
           
$w .= int_to_words($r);
         }
      } else {   
//  millions
        
$w .= int_to_words(floor($x/1000000)) .' million';
        
$r = fmod($x, 1000000);
         if(
$r > 0) {
           
$w .= ' ';
            if(
$r < 100)
              
$word .= 'and ';
           
$w .= int_to_words($r);
         }
      }
   }
   return
$w;
}

?>

Usage:
<?php
echo 'There are currently '. int_to_words($count) . ' members logged on.';
?>
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