# Main interface to C code and data

(PHP 7 >= 7.4.0, PHP 8)

## Introduction

Objects of this class are created by the factory methods FFI::cdef(), FFI::load() or FFI::scope(). Defined C variables are made available as properties of the FFI instance, and defined C functions are made available as methods of the FFI instance. Declared C types can be used to create new C data structures using FFI::new() and FFI::type().

FFI definition parsing and shared library loading may take significant time. It is not useful to do it on each HTTP request in a Web environment. However, it is possible to preload FFI definitions and libraries at PHP startup, and to instantiate FFI objects when necessary. Header files may be extended with special `FFI_SCOPE` defines (e.g. `#define FFI_SCOPE "foo"`; the default scope is "C") and then loaded by FFI::load() during preloading. This leads to the creation of a persistent binding, that will be available to all the following requests through FFI::scope(). Refer to the complete PHP/FFI/preloading example for details.

It is possible to preload more than one C header file into the same scope.

## Class synopsis

final class FFI {
/* Constants */
public const int __BIGGEST_ALIGNMENT__;
/* Methods */
public static addr(FFI\CData `&$ptr`): FFI\CData
public static alignof(FFI\CData|FFI\CType `&$ptr`): int
public static arrayType(FFI\CType `$type`, array `$dimensions`): FFI\CType
public cast(FFI\CType|string `$type`, FFI\CData|int|float|bool|null `&$ptr`): ?FFI\CData
public static cdef(string `$code` = "", ?string `$lib` = `null`): FFI
public static free(FFI\CData `&$ptr`): void
public static isNull(FFI\CData `&$ptr`): bool
public static load(string `$filename`): ?FFI
public static memcmp(string|FFI\CData `&$ptr1`, string|FFI\CData `&$ptr2`, int `$size`): int
public static memcpy(FFI\CData `&$to`, FFI\CData|string `&$from`, int `$size`): void
public static memset(FFI\CData `&$ptr`, int `$value`, int `$size`): void
public new(FFI\CType|string `$type`, bool `$owned` = `true`, bool `$persistent` = `false`): ?FFI\CData
public static scope(string `$name`): FFI
public static sizeof(FFI\CData|FFI\CType `&$ptr`): int
public static string(FFI\CData `&$ptr`, ?int `$size` = `null`): string
public type(string `$type`): ?FFI\CType
public static typeof(FFI\CData `&$ptr`): FFI\CType
}

## Predefined Constants

`FFI::__BIGGEST_ALIGNMENT__`

## Table of Contents

- FFI::addr — Creates an unmanaged pointer to C data
- FFI::alignof — Gets the alignment
- FFI::arrayType — Dynamically constructs a new C array type
- FFI::cast — Performs a C type cast
- FFI::cdef — Creates a new FFI object
- FFI::free — Releases an unmanaged data structure
- FFI::isNull — Checks whether a FFI\CData is a null pointer
- FFI::load — Loads C declarations from a C header file
- FFI::memcmp — Compares memory areas
- FFI::memcpy — Copies one memory area to another
- FFI::memset — Fills a memory area
- FFI::new — Creates a C data structure
- FFI::scope — Instantiates an FFI object with C declarations parsed during preloading
- FFI::sizeof — Gets the size of C data or types
- FFI::string — Creates a PHP string from a memory area
- FFI::type — Creates an FFI\CType object from a C declaration
- FFI::typeof — Gets the FFI\CType of FFI\CData

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