Tutorials

PHP Loops

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

Views: 21570

The For Loop

We used the for loop in our example on how loops work, so you should already have a decent understanding about this loop. The only thing to really understand about the for loop, is that it is the "strictest" loop out of the bunch. It needs a set starting point, and a set ending point. It's useful if you know exactly how many iterations you are dealing with, simple as counting from 1 to 10.

As shown previously:


for (initialization; condition; iteration) {
instruction
}

The condition will always be evaluated before the instruction is complete, and the instruction will be executed before the value is iterated.

initialization -> condition -> instruction -> iteration -> condition -> instruction -> iteration ...

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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