Tutorials

PHP Loops

by Crayon Violent on Jun 19, 2008 2:46:30 PM

Show Me The Money!

The Instruction
The Instruction is what you want PHP to do each iteration of your loop. It can be something as simple as echoing out the current iteration, doing some math based on each iteration, or pulling out a new row of information from a database. This is the "pattern," or "common denominator" to your large chunk of code/content. It's the individual brick that your loop stacks over and over to make your wall.

The most challenging part of making a loop is the Instruction part. Finding the pattern isn't always so easy as our simple condition to test if a number divides evenly by another number. You can use virtually anything inside your loop to build your pattern, from regular assignments/outputs to conditions; you can even put another loop inside your loop! And there's really no limit to how far you can "nest" things inside one another, except for how far you can wrap your head around the logic. Finding a pattern to make a loop out of deserves it's own tutorial altogether. It is what makes looping an artform.

Comments

Again, very nice CV. Only thing i would mention is that it's not strictly true that a for loop requires all 3 parameters. This is a perfectly valid for loop:

As is this:

Of course, they serve no real useful purprose (use a while loop, it's easier to follow) but i had to find something wrong with it :P

1. Ben Smithers on Jun 20, 2008 5:07:40 AM

Ah you are right, but in order for the loops to function properly, they still need to have all the components somewhere. Your first example, while syntactically correct, would in and of itself be an infinite loop. Using your first example, you would have to put the condition and iteration inside the instruction. Example:

I'm glad you pointed that out though : )

2. Crayon Violent on Jun 20, 2008 10:19:46 AM

A concise explanation of loops. Very good.

3. kahratka on Jun 20, 2008 10:32:40 AM
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