08c05-1.php

介绍PHP5的给类型函数应用

<?php
// A function to detect absolute paths:
function is_absolute($path) {
    // Check if it begins with a '/', if so, it is an absolute path
    if ($path{0} == '/') {
        return true;
    } else {
        return false;
    }
}

// A function to detect full/absolute URLs
function is_absoluteurl($path) {
    // Check if it begins with a protocol specification:
    if (preg_match('|^[a-zA-Z]+://|', $path)) {
        return true;
    } else {
        return false;
    }
}

// A function to detect relative paths:
function is_relative($path) {
    // In this case, if it is neither of the absolute options, then
    // it is relative:
    if ( !(is_absolute($path)) && !(is_absoluteurl($path)) ) {
        return true;
    } else {
        return false;
    }
}

// Now, a function that given any path, will turn it into an 
// absolute url and return it:
function ensure_absoluteurl($path) {
    // If this already is an absolute URL, just return it:
    if (is_absoluteurl($path)) {
        return $path;
    }
    // Else if it is an absolute path, add the http & host to it:
    elseif (is_absolute($path)) {
        return "http://{$_SERVER['HTTP_HOST']}{$path}";
    }
    // Finally it is relative, so we need to build the entire string:
    else {
        return 'http://' . $_SERVER['HTTP_HOST'] . 
            dirname($_SERVER['PHP_SELF']) . '/' . $path;
    }
}

// Create some test cases:
$tests = array('http://eliw.com/docs/book/php5/01.php',
    '/docs/book/php5/01.php', 'php5/01.php', '../book/php5/01.php');

// For for each case, run all the functions on it:
foreach ($tests as $tc) {
    echo "<p>\n";
    echo "Is {$tc} relative? ", is_relative($tc) ? 'Yes' : 'No', "<br>\n";
    echo "Is {$tc} absolute? ", is_absolute($tc) ? 'Yes' : 'No', "<br>\n";
    echo "Is {$tc} an absolute URL? ", 
        is_absoluteurl($tc) ? 'Yes' : 'No', "<br>\n";
    echo "Converted to an absolute URL we get: ", ensure_absoluteurl($tc);
    echo "</p>\n";
}
?>