Webmaster in a Nutshell, Second Edition

Variable Manipulation Functions

The following functions operate on PHP variables. There are functions for getting and setting the type of a variable, as well as various ways to encode and decode variables for storage.

bool define(string var_name, mixed value[, int case_sensitive])

Define a constant value

int defined(string constant_name)

Test if a constant is defined

double doubleval(mixed var)

Get the double-precision value of a variable

string getenv(string varname)

Get the value of an environment variable

string gettype(mixed var)

Return the type of the variable

int intval(mixed var [, int base])

Get the integer value of a variable using the optional base for the conversion

bool is_array(mixed var)

Return true if variable is an array

bool is_double(mixed var)

Return true if variable is a double

bool is_float(mixed var)

An alias for is_double

bool is_int(mixed var)

An alias for is_long

bool is_integer(mixed var)

An alias for is_long

bool is_long(mixed var)

Return true if variable is a long (integer)

bool is_object(mixed var)

Return true if variable is an object

string pack(string format, mixed arg1, mixed arg2, ...)

Take one or more arguments and pack them into a binary string according to the format argument

bool is_real(mixed var)

An alias for is_double

bool is_string(mixed var)

Return true if variable is a string

void putenv(string setting)

Set the value of an environment variable

string serialize(mixed variable)

Return a string representation of variable (which can later ...