[php] How to call function of one php file from another php file and pass parameters to it?

I want to call a function in one PHP file from a second PHP file and also pass two parameters to that function. How can I do this?

I am very new to PHP. So please tell me, should I include the first PHP file into the second?

Please show me an example. You can provide some links if you want.

file1.php

<?php

    function func1($param1, $param2)
    {
        echo $param1 . ', ' . $param2;
    }

file2.php

<?php

    require_once('file1.php');

    func1('Hello', 'world');

See manual

Yes include the first file into the second. That's all.

See an example below,

File1.php :

<?php
  function first($int, $string){ //function parameters, two variables.
    return $string;  //returns the second argument passed into the function
  }
?>

Now Using include (http://php.net/include) to include the File1.php to make its content available for use in the second file:

File2.php :

<?php
  include 'File1.php';
  echo first(1,"omg lol"); //returns omg lol;
?>

files directory:

Project->

-functions.php

-main.php

functions.php

function sum(a,b){
 return a+b;
}
function product(a,b){
return a*b;
}

main.php

require_once "functions.php";
echo "sum of two numbers ". sum(4,2);
echo "<br>"; //  create break line
echo "product of two numbers ".product(2,3);

The Output Is :

sum of two numbers 6 product of two numbers 6

Note: don't write public before function. Public, private, these modifiers can only use when you create class.

you can write the function in a separate file (say common-functions.php) and include it wherever needed.

function getEmployeeFullName($employeeId) {
// Write code to return full name based on $employeeId
}

You can include common-functions.php in another file as below.

include('common-functions.php');
echo 'Name of first employee is ' . getEmployeeFullName(1);

You can include any number of files to another file. But including comes with a little performance cost. Therefore include only the files which are really required.