Tutorials

PHP Loops

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

Views: 25161

Let's Get Loopy

All loops are broken down into four basic pieces:

- The initialization
- The condition
- The instruction
- The iteration

A basic "for" loop looks like this:


for (initialization; condition; iteration) {
instruction
}

We start out with telling PHP what kind of loop it is. Since it is a "for" loop, we start out by simply saying "for ..." The initialization, condition, and iteration are put inside the ( )'s, separated by a semicolon. We use { } brackets to show where the start and end of our instruction is. Some people like to put the { on its own line like this:


for (initialization; condition; iteration)
{
instruction
}

It's really just a matter of style; PHP doesn't care either way.

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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