PHP的compact()函數(shù)通過(guò)變量名字符串創(chuàng)建關(guān)聯(lián)數(shù)組，使用方式為傳遞變量名作為參數(shù)，如compact('var1', 'var2')。 1. 函數(shù)將變量名映射為數(shù)組鍵，值為其當(dāng)前值；2. 若變量不存在，則靜默忽略；3. 常用於批量傳遞變量至模板或函數(shù)，提升代碼簡(jiǎn)潔性；4. 支持傳入字符串?dāng)?shù)組，如compact(['a', 'b'])等同於逐個(gè)傳參；5. 注意變量名拼寫(xiě)必須正確，且存在於當(dāng)前作用域，否則無(wú)法獲取值。

The compact() function in PHP is a handy tool for creating an associative array from existing variables. It takes one or more variable names as strings and returns an array where the keys are the variable names and the values are the corresponding variable values.

How to Use compact()

The basic syntax is:

 compact(var1, var2, ...)

Each argument is a string representing the name of a variable. Here's a simple example:

 $name = "Alice";
$age = 30;

$result = compact('name', 'age');

print_r($result);
// Output:
// Array
// (
// [name] => Alice
// [age] => 30
// )

If the variable doesn't exist, it won't be included in the result — no error, just silently skipped.

When You Might Use It

A common use case is when you're passing multiple variables to a template or function and want to avoid repeating yourself.

For example, instead of writing:

 extract(compact('title', 'content', 'author'));

You could use compact() directly to pass data into another context like a view renderer.

This becomes especially useful in frameworks or templating systems where you might want to bundle related variables together without manually building the array.

What to Watch Out For

One thing that trips people up: compact() uses the variable name as a string to look up the value. So if you have a typo or misspell the variable name, it simply won't show up in the output.

Also, if you're using variable variables or dynamic variable names, compact() may not behave how you expect. For instance:

 $a = 1;
$b = 2;
$varNames = ['a', 'b'];

$result = compact($varNames); // This works!

Yes, you can also pass an array of strings, like this:

 compact(['a', 'b']);

Which gives the same result as compact('a', 'b') .

But if you try to do something like dynamically generating the list of variable names, make sure they're valid strings and that those variables actually exist in the current scope.

So, yeah — compact() is straightforward once you get used to how it pulls in variables by name. Just remember it's looking for real variables in the current context and ignores any names that don't match.

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