How to use PHP's built-in function debugging tools?

PHP's built-in debugging tools include print_r(), var_dump(), and debug_backtrace(), which print variable values ​​in a human-readable manner, provide more detailed variable information, and create arrays containing call stack information, respectively. In practical cases, you can use var_dump() to print variable values ​​to facilitate debugging the code.

How to use PHP built-in debugging tools

PHP provides a number of built-in functions to help you simplify the debugging process. The following are several commonly used tools:

1. print_r()

This function prints the variable value in a human-readable way. It is useful for debugging arrays and objects.

<?php
$array = ['name' => 'John Doe', 'age' => 30];
print_r($array);
?>

Output:

Array
(
    [name] => John Doe
    [age] => 30
)

2. var_dump()

is similar to print_r(), var_dump( ) also prints variable values, but it provides more detailed information, including data types and references.

<?php
$object = new stdClass();
$object->name = 'John Doe';
$object->age = 30;

var_dump($object);
?>

Output:

object(stdClass)#2 (2) {
  ["name"]=>
  string(6) "John Doe"
  ["age"]=>
  int(30)
}

3. debug_backtrace()

This function creates an array containing call stack information. This is useful for tracing the order of function calls.

<?php
function foo() {
    debug_backtrace();
}

foo();

Output:

[0] => Array
    (
        [file] => /path/to/file.php
        [line] => 17
        [function] => foo
        [args] => Array
            (
            )
        [object] => Array
            (
            )
    )

Practical case:

Suppose you have the following PHP code:

<?php
function addNumbers($a, $b) {
    $sum = $a + $b;
    return $sum;
}

$result = addNumbers(1, 2);
echo $result;
?>

When debugging this code, You can use var_dump() to print the value of $sum:

<?php
function addNumbers($a, $b) {
    $sum = $a + $b;
    var_dump($sum);
    return $sum;
}

$result = addNumbers(1, 2);
echo $result;
?>

This will print the value of sum when the code is run:

int(3)

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