php使用正则表达式编写程序验证URL地址是否符合要求？要求：请使用自定义函数编写并验证2个URL地址是否符合要求。

Sure, I can help you with that. Here's a sample code for validating URLs using regular expressions in PHP:

<?php

function isValidUrl($url) {
  $pattern = '/^(https?|ftp):\/\/[^\s\/$.?#].[^\s]*$/i';
  return preg_match($pattern, $url) === 1;
}

// Sample usage
$url1 = 'https://www.example.com/index.html';
$url2 = 'ftp://ftp.example.com/test/file.txt';
if (isValidUrl($url1)) {
  echo $url1 . ' is a valid URL';
} else {
  echo $url1 . ' is not a valid URL';
}
if (isValidUrl($url2)) {
  echo $url2 . ' is a valid URL';
} else {
  echo $url2 . ' is not a valid URL';
}

?>

This code defines a custom function `isValidUrl()` that takes a URL string as input and uses a regular expression pattern to check whether it's a valid URL or not. It returns `true` if the URL is valid and `false` otherwise. You can use this function to validate any number of URLs by passing them as arguments. Note that the regular expression pattern used here is a simplified version and may not catch all edge cases.