Php 简明教程

PHP Variable Handling Functions

PHP Variable Handling Functions 是内置的 PHP 库函数，使我们能够以多种方式操作和测试 PHP 变量。

PHP Variable Handling Functions are the inbuilt PHP library functions that enable us to manipulate and test php variables in various ways.

Installation

无需安装即可使用 PHP 变量处理函数；它们是 PHP 内核的一部分，并随标准 PHP 安装一起提供。

There is no installation needed to use PHP variable handling functions; they are part of the PHP core and comes alongwith standard PHP installation.

Runtime Configuration

此扩展没有在 php.ini 中定义任何配置指令。

This extension has no configuration directives defined in php.ini.

PHP Variable Handling Functions

下表列出了与 PHP 变量处理相关的所有函数。此处的版本列表示支持该函数的 PHP 最早版本。

Following table lists down all the functions related to PHP Variable Handling. Here column version indicates the earliest version of PHP that supports the function.

Sr.No	Function & Description	Version
1	boolval()Function returns boolean value of a defined variable, i.e, it returns TRUE or FALSE.	5.5.0
2	debug_zval_dump()Function is used to dump a string representation of an internal zend value to output.	4.2.0
3	doubleval()Function is used to return the float value of a defined variable.	4, 5, 7, 8
4	empty()Function is used to check if the defined variable has empty value.	4, 5, 7, 8
5	floatval()Function used return the float value of a defined variable.	4.2.0, 5, 7, 8
6	get_defined_vars()Function is used to return all the defined variables as an array.	4.0.4, 5, 7, 8
7	get_resource_id()Function is used to return an integer identifier for the given resource.	8
8	get_resource_type()Function returns the type a resource of the variable defined.	4.0.2, 5, 7, 8
9	gettype()Function returns the type of the variable defined.	4, 5, 7, 8
10	intval()Function returns integer value of the defined variable.	4, 5, 7, 8
11	is_array()Function is used to check if the defined variable is an array.	4, 5, 7, 8
12	is_bool()Function is used to check if the defined variable is boolean, i.e, it returns true or false value.	4, 5, 7, 8
13	is_callable()Function is used to check if the data in the variable can be called as a function	4.0.6, 5, 7, 8
14	is_countable()Function is used to check if the data in the variable is countable.	7.3.0, 8
15	is_double()Function is used to check if the variable defined is of the type float	4, 5, 7, 8
16	is_float()Function is used to check if the variable defined is an float	4, 5, 7, 8
17	is_int()Function is used to check if the variable defined is of the type integer	4, 5, 7, 8
18	is_integer()Function is used to check if the variable defined is an integer.	4, 5, 7, 8
19	is_iterable()Function is used to check if the data in the variable is an iterable value.	7.1.0, 8
20	is_long()Function is used to check if the variable is of the type integer.	4, 5, 7, 8
21	is_null()Function checks if the variable has NULL value.	4.0.4, 5, 7, 8
22	is_numeric()Function is used to check if the defined variable is numeric or a numeric string.	4, 5, 7, 8
23	is_object()Function is used to check if the variable is an object.	4, 5, 7, 8
24	is_real()Function is used to check if the defined variable is of the type float or not.	4, 5, 7, 8
25	is_resource()Function is used to check if the defined variable is resource.	4, 5, 7, 8
26	is_scalar()Function is used to check if the defined variable is scalar.	4.0.5, 5, 7, 8
27	is_string()Function is used to check if the defined variable is of the type string.	4, 5, 7, 8
28	isset()Function is used to check if a variable is declared and set.	4, 5, 7, 8
29	print_r()Function used to represent or print the data of a variable into a readable format.	4, 5, 7, 8
30	serialize()Function used to convert the data of a variable into a storable representation, so that the data can be stored in a file, a memory buffer	4, 5, 7, 8
31	settype()Function is used to set a variable into a specific type.	4, 5, 7, 8
32	strval()Function is used to return a string value of a variable.	4, 5, 7, 8
33	unserialize()Function is used to unserialize the data of a variable. i.e, this function returns actual data of a serialize variable.	4, 5, 7, 8
34	unset()Function used unset a variable	4, 5, 7, 8
35	var_dump()Function is used to dump information about one or more variables. The information holds type and value of the variable(s).	4, 5, 7, 8
36	var_export()Function returns structured information about a variable.	4.2.0, 5, 7, 8