Is it necessary to use quotes around php array key names?

In PHP, we often use arrays to store and manipulate data. When we create an array, we need to assign a key name (or index) and corresponding value to each element in the array. So, is it necessary to use quotation marks for the key names in the array?

In fact, array key names in PHP can be divided into two types: string type and integer type. If we use a string key name, we can choose whether to use quotes when defining it. For example, the following code snippet creates an array containing string key names:

$fruits = array(
   "apple" => "red",
   "banana" => "yellow",
   "orange" => "orange"
);

In this array, we use double quotes to enclose the key names. The advantage of this is that it ensures that the key name does not contain any special characters, such as spaces, brackets, etc., to avoid syntax errors.

Of course, if the key name does not contain special characters, we can also not use quotation marks. For example, the following code snippet also creates an array containing string type keys:

$fruits = array(
   apple => "red",
   banana => "yellow",
   orange => "orange"
);

In this array, we omit the double quotes and use string type keys directly.

It should be noted that if the key name contains numbers or other special characters, it must be enclosed in quotation marks. For example, the following code snippet will cause a syntax error:

$fruits = array(
   apple-123 => "red",
   banana => "yellow",
   orange => "orange"
);

In this array, we used apple-123 as the key name, but did not use quotation marks, resulting in a syntax error .

In addition, if we use integer type key names, there is no need to use quotation marks. For example, the following code snippet creates an array containing integer keys:

$numbers = array(
   0 => "zero",
   1 => "one",
   2 => "two"
);

In this array, we use integers as keys directly without using quotes.

To sum up, whether the key name in the PHP array needs to be enclosed in quotation marks depends on the specific situation. If the key name contains special characters or numbers, it should be enclosed in quotes to avoid syntax errors. If the key name does not contain special characters, the quotes can be omitted. In short, you should always pay attention to the readability and maintainability of your code.

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