Cameron Garnett/Testpage11

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PHP

Super Quick PHP Tutorial

Introduction | Basic Syntax | Sending Data to the Browser | Comments | Variables | Strings | Functions | Quotes | Debugging | Form


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Learning Objectives

By the end of this page you will know some technique's used when you are debugging php code.

Debugging

Return values returns an associative array describing the last error with keys "type", "message", "file" and "line". If the error has been caused by a PHP internal function then the "message" begins with its name. Returns NULL if there hasn't been an error yet


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Example

<?php
echo $a;
print_r(error_get_last());
?>

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This should output something similar to:

Array
(
[type] => 8
[message] => Undefined variable: a
[file] => C:\WWW\index.php
[line] => 2
)


In the next example the debug_backtrace() function is used. debug_backtrace() generates a PHP backtrace.

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Example

<?php
// filename: /tmp/a.php

function a_test($str)
{
echo "\nHi: $str";
var_dump(debug_backtrace());br> }

a_test('friend');
?>

<?php
// filename: /tmp/b.php
include_once '/tmp/a.php';
?>

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This should out put something similar to:

Hi: friend array(2) {
[0]=>
array(4) {
["file"] => string(10) "/tmp/a.php"
["line"] => int(10)
["function"] => string(6) "a_test"
["args"]=>
array(1) {
[0] => &string(6) "friend"
}
}
[1]=>
array(4) {
["file"] => string(10) "/tmp/b.php"
["line"] => int(2)
["args"] =>
array(1) {
[0] => string(10) "/tmp/a.php"
}
["function"] => string(12) "include_once"
}
}

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