Using php.exe you can easily check your code for error. By running this command at a command line:
php -l <FileName>
ex.) php -l C:\text.php
PHP will check the file for errors. This saves you from having to upload it and test. Of course that would be too tedious for most people so get yourself a good text editor that has the option of running tools. This way you can easily check the current file being edited. (ex.) TextPad, Editplus)
The are many other commands you can use too. Just type
at a command line prompt to see the other options.
EDIT: To do this is EditPlus just go to Tools < Configure User Tools. Then click Add Tool < Program. Next to the Command box is a little button, click and browse for php.exe. In the Argument box type -l and then click the little arrow next to the box. Select FileName from the list. The Argument box should look like: -l $(FileName). Then select Capture Output. Click ok and go to View < Toolbars/Views < Output Window. Then just open a PHP document and click on the tool icon an the output should display in the Output Window.