How can we call a C language shared library in PHP?

2 years ago
Isabella Edwards
2 minutes

To call a C language .so dynamic library in PHP, you can utilize PHP’s FFI (Foreign Function Interface) extension.

First, make sure your PHP version supports the FFI extension. Run “php -m” in the command line and check if FFI is included in the output.

Next, create a PHP script that uses the FFI extension to load a .so dynamic library written in C language and call its functions. Here is an example:

<?php
$ffi = FFI::cdef("
    // 在这里定义C语言函数的签名
    int add(int a, int b);
", "path/to/your/library.so");

$result = $ffi->add(2, 3);
echo $result;  // 输出：5
?>

In the example above, we first defined the signature of a C function using the FFI::cdef() function, then loaded the .so dynamic library using FFI(). Afterwards, we can call the C function directly using the $ffi object, similar to calling a PHP function.

In the FFI::cdef() function, you must provide the signature of the C language function, which includes the function name and parameter types, as well as the path to the dynamic library. Within the parentheses after the function name, you can specify the types of parameters the function accepts, for example, int add(int a, int b) indicates that the add function takes two integer parameters and returns an integer result.

Finally, by invoking $ffi->add(2, 3), we successfully called the C function add and assigned the result to the $result variable. Ultimately, we used the echo statement to output the result.

Important points to note:

  1. You need to replace “path/to/your/library.so” with the actual path to your .so dynamic library file.
  2. If your .so dynamic library depends on other libraries, you may need to set the LD_LIBRARY_PATH environment variable before loading to specify the search path for the dynamic library.

I hope this example can help you successfully call the .so dynamic library in C language.

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