Документация PHP
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print_r
(PHP 4, PHP 5)
print_r — Prints human-readable information about a variable
Описание
mixed print_r ( mixed $expression [, bool $return ] )
print_r() displays information about a variable in a way that's readable by humans.
print_r(), var_dump() and var_export() will also show protected and private properties of objects with PHP 5. Static class members will not be shown.
Remember that print_r() will move the array pointer to the end. Use reset() to bring it back to beginning.
Список параметров
- expression
-
The expression to be printed.
- return
-
If you would like to capture the output of print_r(), use the return parameter. If this parameter is set to TRUE, print_r() will return its output, instead of printing it (which it does by default).
Возвращаемые значения
If given a string, integer or float, the value itself will be printed. If given an array, values will be presented in a format that shows keys and elements. Similar notation is used for objects.
Примечания
Замечание: This function uses internal output buffering with this parameter so it can not be used inside an ob_start() callback function.
Список изменений
| Версия | Описание |
|---|---|
| 4.3.0 | The return parameter was added. If you need to capture the output of print_r() with an older version of PHP prior, use the output-control functions. |
| 4.0.4 | Prior to PHP 4.0.4, print_r() will continue forever if given an array or object that contains a direct or indirect reference to itself. An example is print_r($GLOBALS) because $GLOBALS is itself a global variable that contains a reference to itself. |
Примеры
Пример #1 print_r() example
<pre>
<?php
$a = array ('a' => 'apple', 'b' => 'banana', 'c' => array ('x', 'y', 'z'));
print_r ($a);
?>
</pre>
Результат выполнения данного примера:
<pre>
Array
(
[a] => apple
[b] => banana
[c] => Array
(
[0] => x
[1] => y
[2] => z
)
)
</pre>
Пример #2 return parameter example
<?php
$b = array ('m' => 'monkey', 'foo' => 'bar', 'x' => array ('x', 'y', 'z'));
$results = print_r($b, true); // $results now contains output from print_r
?>
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