Tag Archives: regex

Regular Expressions

Here is a topic that has really flustered a lot of developers. Regular expressions is a concept that can be hard to get a real handle on. PHP has a couple of functions that can help do regular expressions. The one I focus on most is using the function:

This is a very useful tool, and if you look at the PHP manual for ereg(), it states that the function “preg_match” is a faster alternative to “ereg()”. Now while I am not going to get into the details of the speed and response times for both functions, as there will always be someone with a different opinion or case that shows how their way is better, and that is fine. What most people have a hard time dealing with is getting the actual match to do what is needed. There are times when It is just easier to do a Google search and get some code that someone else has already done and plug it in. But the real power is knowing what you are doing first, that way you can build your own.

For this example, we can take a look at CakePHP’s own little validation object. When you set up a model and add some validation to it, it calls this object. Based on the data that this going into the tables, it will call one of these functions. The way these functions work is by checking the input for a specific character list/set that should be contained in the text. If the entry does not match up, then it is not validated. The way CakePHp does this is by using the preg_match() function.
Continue reading Regular Expressions