How to solve PHP error: unexpected ']' symbol?

How to solve PHP error: unexpected "]" symbol?

Introduction: During the PHP development process, we often encounter various error prompts. One of the common errors is "unexpected "]" symbol". This error message often confuses beginners because the specific cause and solution are usually not clear. This article will answer this question in detail and provide corresponding code examples.

1. Error message
   When an unexpected "]" symbol appears in the PHP code, the following error message will be displayed:

   Parse error: syntax error, unexpected ']' in filename.php on line X

   Among them, "filename .php" refers to the name of the PHP file where the error occurred, and "X" refers to the line number of the code where the error occurred.

2. Cause of error
   This error is usually caused by the structure problem of array, associative array or index array. Specifically, it may be the following situations:
3. The array index is invalid or there is a syntax error;
4. The key-value pair of the array is not written in the correct format.
5. Solution
   Solving this error can be divided into two situations.

3.1 The array index is invalid or there is a syntax error
When the array index is invalid or there is a syntax error, you can follow the following steps to solve it:

Step 1: Check whether the array index is There are grammatical errors, such as an extra comma, an extra right bracket, etc.;

$names = array(
    "John",
    "Michael",
    "David",
    "Sarah",
); 

In this example, due to an extra comma after the last element, an "unexpected "]" symbol will appear" mistake.

The solution is to delete the extra commas to solve this error:

$names = array(
    "John",
    "Michael",
    "David",
    "Sarah"
); 

Step 2: Confirm whether the array index is correct, such as checking whether there is a defined variable, function or class name as index.

$name = "John";
$age = 30;
$person = [
    $name,
    $age,
];

In this example, since $name and $age are variables and cannot be used as array indexes, an "unexpected "]" symbol error will occur.

The solution is to replace the legal array index, such as using a numeric index:

$name = "John";
$age = 30;
$person = [
    0 => $name,
    1 => $age,
];

3.2 The array key-value pair is not written in the correct format
When the array key-value pair is not written in the correct format When writing in the format, you can follow the following steps to solve the problem:

Step 1: Check whether the array key-value pair uses the correct syntax format, that is, in the form of $key => $value.

$person = [
    "name": "John",
    "age" => 30,
];

In this example, because the key-value pair of the array uses the wrong syntax format, that is, a colon is used instead of the equal sign, an "unexpected "]" symbol error will occur.

The solution is to use the correct syntax format, that is, use the equal sign:

$person = [
    "name" => "John",
    "age" => 30,
];

Step 2: Check whether the key name is legal. Undefined constants cannot be used as key names.

define("PI", 3.14);
$person = [
    PI => "John",
    "age" => 30,
];

In this example, because the PI constant is not defined, an "unexpected "]" symbol error will occur.

The solution is to use legal key names, such as using strings as key names:

define("PI", 3.14);
$person = [
    "PI" => "John",
    "age" => 30,
];

Summary: During the PHP development process, when an "unexpected "]" symbol" error occurs When doing this, we should first carefully check whether there are syntax errors in the array indexes and key-value pairs in the code. If the code syntax is correct, you also need to check whether the structure of the array complies with the specification. By determining the type of error and following the appropriate solution to fix it, we can solve the problem and make the PHP code run normally.

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