Added new exceptions page

code/exceptions.php

@@ -0,0 +1,60 @@
+<?php
+
+// Sometimes things go wrong when someone uses your code. How do we handle this situation?
+// PHP has Exceptions to define errors and the ability to "throw" them to stop code
+// execution and tell the user of your code that something is wrong.
+class Processor
+{
+    public function charge($creditCard)
+    {
+        if (strlen($creditCard->getNumber()) !== 16) {
+            throw new Exception('Credit card is not right');
+        }
+    }
+}
+
+// In this case, if someone tried to use the Processor class
+// to charge a credit card number that is not 16 characters long, an
+// exception will be thrown which stops the rest of the code from running.
+$processor = new Processor();
+$processor->charge('1234');
+
+// A developer who wants to prevent an exception from stopping code execution
+// can catch the exception and use it for logging or a return an error to a user.
+
+// Just wrap the code that might throw an exception with the keyword "try" and brackets
+// followed by "catch", the exception type in parentheses and more brackets.
+try {
+    $processor->charge('1234');
+} catch (Exception $e) {
+    echo $e->getMessage() . "\n";
+}
+
+// You can make your own custom exceptions as well. They are just classes
+// that extend Exception.
+class MyCustomException extends Exception {}
+
+// Then, you can try to catch your exception instead of the base exception.
+try {
+    throw new MyCustomException('I am a custom exception');
+} catch (MyCustomException $e) {
+    echo "Cauth MyCustomException\n";
+}
+
+// Since all exceptions inherit from Exception, catching
+// Exception will catch any and all exceptions that might be thrown.
+try {
+    throw new MyCustomException('I inherit from Exception');
+} catch (Exception $e) {
+    echo "Still caught MyCustomException\n";
+}
+
+// You can also create multiple catch blocks to handle different types of exceptions in
+// one try-catch.
+try {
+    throw new MyCustomException('I am being thrown again');
+} catch (MyCustomException $e) {
+    echo "MyCustomException was caught\n";
+} catch (Exception $e) {
+    echo "Just in case a different exception is thrown\n";
+}