How to debug custom PHP functions?

Steps to debug custom PHP functions: Use var_dump() and print_r() to check the return value. Use error_log() to log error messages. Install the Xdebug extension to set breakpoints and view variables. Use the PHPStorm IDE to step through debugging and inspect variables. Log parameters and return values ​​to track function behavior. Add a log statement to record the execution steps of the function.

How to debug custom PHP functions

Debugging custom PHP functions is critical to identifying and fixing errors. This article will introduce various debugging technologies through practical cases.

Practical Case

Suppose you have a custom function called calculate_sum(), but it doesn’t work as expected. The calling code is as follows:

<?php
function calculate_sum($numbers) {
  $sum = 0;
  foreach ($numbers as $number) {
    $sum += $number;
  }
  return $sum;
}

$result = calculate_sum([1, 2, 3]);
echo $result; // 返回 5
?>

However, in this case, the function returns 0 instead of 6.

Debugging techniques

1. Use var_dump() and print_r()

echo '<pre class="brush:php;toolbar:false">';
var_dump(calculate_sum([1, 2, 3]));
print_r(calculate_sum([1, 2, 3]));
echo '

';

This will output the details of the function's return value to the browser, helping you check for unexpected data types or values.

2. Use error_log()

error_log('Function returned: ' . calculate_sum([1, 2, 3]));

This will log the error message to the server's error log where you can view the function The return value.

3. Use Xdebug

Xdebug is a PHP extension that provides powerful debugging capabilities. It allows you to set breakpoints, inspect variables and view function call stacks.

4. Use PHPStorm

PHPStorm is an IDE (Integrated Development Environment) that provides a more intuitive debugging experience. It allows you to set breakpoints, perform step-by-step debugging and inspect variables.

5. Record parameters and return values

Record parameters and return values ​​at the beginning and end of the function to track the behavior of the function under different input data.

6. Add log statements

Add log statements at key locations to record the various steps of function execution. This helps identify errors and trace the logical flow of a function.

With these techniques, you can effectively debug custom PHP functions, identify and fix errors, and ensure that functions work as expected.

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