urlencode()函數(shù)用於將字符串編碼為URL安全格式，其中非字母數(shù)字字符（除-、_和.外）會被替換為百分號後跟兩位十六進制數(shù)的形式。例如，空格轉(zhuǎn)為號，感嘆號轉(zhuǎn)為!，而中文字符則轉(zhuǎn)換為其UTF-8編碼形式。使用時應僅對參數(shù)值進行編碼，而非整個URL，以避免破壞URL結(jié)構(gòu)。對於URL的其他部分如路徑段，應使用rawurlencode()函數(shù)，其將空格轉(zhuǎn)為。處理數(shù)組參數(shù)時可使用http_build_query()自動編碼，或手動對每個值調(diào)用urlencode()以確保安全傳輸數(shù)據(jù)。正確選擇函數(shù)並按需應用是關(guān)鍵。

當你need to encode a string for use in a URL using PHP， urlencode() is the go-to function. It converts special characters into their percent-encoded representations, making sure your data is transmitted correctly over HTTP.

What does urlencode() do?

This function takes a string and returns a new string where all non-alphanumeric characters (except - , _ , and . ) are replaced with a % followed by two hexadecimal digits. For example, spaces become , and Chinese characters get converted into their UTF-8 encoded form like你.

If you're building query strings manually or passing dynamic values in URLs, this encoding is essential to avoid breaking the URL structure.

How to use urlencode() – basic examples

Here's how it works in practice:

 echo urlencode("Hello World!"); // Outputs: Hello World!

Notice that the space becomes a plus sign ( ) and the exclamation mark becomes ! . This behavior follows the application/x-www-form-urlencoded MIME type rules.

You might commonly use it when constructing URLs with GET parameters:

 $title = "My awesome blog post!";
$url = "https://example.com/blog?title=" . urlencode($title);
// Resulting URL: https://example.com/blog?title=My awesome blog post!

Some key points:

• Always apply urlencode() to individual parameter values, not the full URL.
• Don't encode the entire URL — that would mess up the structure (like turning ? into ? ).
• Use it before appending values to query strings.

When to use rawurlencode() instead

There's also a similar function called rawurlencode() . The main difference is that rawurlencode() follows RFC 3986 and encodes the space character as instead of .

So if you're working with parts of a URL other than query strings (eg, path segments), rawurlencode() may be more appropriate:

 echo rawurlencode("Hello World!"); // Outputs: Hello World!

Use these guidelines to choose between them:

• Use urlencode() for query string parameters.
• Use rawurlencode() for encoding URI components like paths or slugs.

Handling arrays and multiple parameters

PHP can automatically handle array-style query parameters when building URLs:

 $params = ['color' => 'blue', 'size' => ['large', 'medium']];
echo http_build_query($params);
// Outputs: color=blue&size[0]=large&size[1]=medium

But if you're doing it manually and want to encode each value yourself, still use urlencode() :

 $values = ['red', 'green', 'blue'];
foreach ($values as $value) {
    $query .= '&color[]=' . urlencode($value);
}

This gives you more control while ensuring safe encoding.

基本上就這些。用對函數(shù)、分清場景、別提前編碼整個URL，問題就不大。

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