Common Misunderstandings in PHP Debugging, Avoid Falling into Traps

Common misunderstandings in PHP debugging: Reliance on echo/print Debugging: Use var_dump() or print_r() to clearly display variables. Ignore debug level setting: Set error level to E_ALL to display all information. Arithmetic operations on NULL values: Use the ternary operator or the isset() function to handle NULL values. Exceptions not handled properly: Catch and handle exceptions appropriately to get information about the runtime error.

Common misunderstandings in PHP debugging, avoid falling into traps

Myth 1: Relying only on echo/print statements for debugging

• It's easy to use echo() to print variables or perform calculations, but it can quickly become cluttered when dealing with complex code.

  // 错误示例
  echo $variable;
  echo calculateSomething();

Best practice: Use var_dump() or print_r() function to clearly display variables and its type.

var_dump($variable);
print_r(calculateSomething());

Myth 2: Ignoring setting the debug level

• PHP does not display all errors or warnings by default. Make sure to set the debug level to E_ALL to display all information.

  // 在脚本顶部添加以下代码
  error_reporting(E_ALL);
  ini_set('display_errors', 'On');

Myth 3: Arithmetic operations on NULL values

• NULL values ​​cannot be used Make numbers. Always check for NULL values ​​before comparing or assigning.

  // 错误示例
  $sum = 10 + NULL;

Best Practice: Use the ternary operator or the isset() function to handle NULL values.

$sum = isset($number) ? 10 + $number : 10;

Myth 4: Exceptions are not handled correctly

• Exceptions provide valuable information about runtime errors. Be sure to catch it and handle it appropriately.

  try {
    // 你的代码
  } catch (Exception $e) {
    // 处理异常
  }

Practical case:

Suppose we have a function calculateAverage() to calculate the average of a set of numbers . Here is an example of debugging using the above best practices:

// 设置调试级别
error_reporting(E_ALL);
ini_set('display_errors', 'On');

// 定义测试数据
$numbers = [10, 20, 30, 40, 50];

// 计算平均值并打印结果
try {
    $average = calculateAverage($numbers);
    var_dump($average); // 输出：30
} catch (Exception $e) {
    echo "Error: " . $e->getMessage();
}

// calculateAverage() 函数：
function calculateAverage(array $numbers): float
{
    if (empty($numbers)) {
        throw new Exception("Cannot calculate average of an empty array.");
    }
    $sum = 0;
    foreach ($numbers as $number) {
        if (!is_numeric($number)) {
            throw new Exception("Invalid number in the array.");
        }
        $sum += $number;
    }
    return $sum / count($numbers);
}

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