Quickstart from Rasmus Lerdorf's 25 years of PHP talk. 
<?php
$ffi = FFI::cdef(
    "int printf(const char *format, ...);",
    "libc.so.6");
$ffi->printf("Hello %s!\n", "world");
?>
Requires ffi.enable=1Quickstart from Rasmus Lerdorf's 25 years of PHP talk. 
<?php
$ffi = FFI::cdef(
    "int printf(const char *format, ...);",
    "libc.so.6");
$ffi->printf("Hello %s!\n", "world");
?>
Requires ffi.enable=1