debugging PHP code example

Example 1: how to debug in php

ini_set('display_errors', 'On');
error_reporting(E_ALL);

Example 2: php best debugging functions

<?php
$myVar = "hello world!";

var_dump($myVar);
print_r($myVar);

$allVars = get_defined_vars();
print_r($allVars);
debug_zval_dump($allVars);

function sayHello($hello) {
    echo $hello;
    debug_print_backtrace();
}

sayHello($myVar);
?>

Example 3: php best debugging functions

I am using two ways to debug code

one is print the data and die the function in specific point.
 
     print_r($data);die;

second one is writing log file in specific point in code.

function write_log($log_msg)
{
    $log_filename = "logs";
    if (!file_exists($log_filename)) 
    {
        mkdir($log_filename, 0777, true);
    }
    $log_file_data = $log_filename.'/debug.log';
  file_put_contents($log_file_data, $log_msg . "\n", FILE_APPEND);
    
} 

write_log("Writing Log");
$a = array(
        array('id' => '1','date' => '09-04-2018','length' => '10'),
        array('id' => '2','date' => '09-04-2018','length' => '20'),
        array('id' => '1','date' => '10-04-2018','length' => '11')
    );
write_log(print_r($a,1));

Example 4: php best debugging functions

I find it very useful to print out to the browsers console instead of just var_dumping:

function console_log( $data ){
  echo '<script>';
  echo 'console.log('. json_encode( $data ) .')';
  echo '</script>';
}

Usage:
$myvar = array(1,2,3);
console_log( $myvar ); // [1,2,3]

Example 5: php best debugging functions

A good example of data output to the console via <script> tags, I myself used this first, but he broke the captcha job, because <script> tags were inserted into the base64 code of the captcha picture. Then I began to display logs in the headers with such a function (it may help someone else, in a similar situation):

<?php

function header_log($data){
  $bt = debug_backtrace();
  $caller = array_shift($bt);
  $line = $caller['line'];
  $file = array_pop(explode('/', $caller['file']));
  header('log_'.$file.'_'.$caller['line'].': '.json_encode($data));
}

?>

Usage:
$myvar = array(1,2,3);
header_log( $myvar ); // in headers we see: log_filename_rownumber: [1,2,3]

Example 6: debug php

// ------ string -------
// use echo, exit for output
$a = 123
echo ($a);
exit;


// ------ array -------
$array = array(
	1 => 'apple',
  	2 => 'banana',
)

// Method 1
echo "<pre>";
print_r($array);
echo "</pre>";

// Method 2 
echo "<pre>";
var_dump($array);
echo "</pre>";

// Method 3 (no need exit) beacause of dd is already exit
dd($array)
  
// Method 4 (cakephp)
pr ($array);


// ------ json -------
$json = {"a":"123"}

pr (json_encode($json));
exit;

print_r (json_encode($json));
exit;