[RESOLVED] "echo" and "header"

NoBullMan

Hi,
how can I, at some point in my code, redirect the user to a different page if I have "echo" statements in the code? It seems I cannot have any :echo"s before header or else I get an error saying "header already been sent at line xxxx" where ine xxxx refers to the "echo" statement.

Thanx.

jpmoriarty

you can do it with buffering i think, but why would you want to? if you're redirecting, then the page will disapear, so anything you've outputted will dissapear anyway.

you can also use a html redirect, but that needs to go into your <head> section of the page.

coditoergosum

You really should read up on the http protocol. It's VERY important for a web developer to understand it completely. Anyone have a link to a good tutorial?

That being said, the quick and easy answer is no, you cannot echo anything to the browser before sending headers. Not only can you not echo, you can't send any data to the browser before sending a header. This includes white space, html... anything.

I would suggest you rewrite you scripts to do any redirection before anything else... if you're going to redirect them. You could actually send some javascript or even a meta refresh tag to the browser to make it go somewhere else, but in my opinion that isn't a good practice.

csousley

Just to back up coditoergosum, javascript will work, but you should really rewrite the page.

Just incase:

NoBullMan

Thanks for the info, guys.
Let's say I want to display some message to the user before sending him back to a different page, how would I do it?
I have some javascript code that displays an "alert" or "confirm" window. I have done it using echo "<javascript>confirm(....)"
I am novice so I appreciate your guidance.

Weedpacket

Originally posted by NoBullMan
Thanks for the info, guys.
Let's say I want to display some message to the user before sending him back to a different page, how would I do it?
I have some javascript code that displays an "alert" or "confirm" window. I have done it using echo "<javascript>confirm(....)"
I am novice so I appreciate your guidance.

In that case, jpmoriarty's suggestion would be what you're after. An http redirect is saying "No! Don't look at that page! Look at this page!"

Hmmmm .... I think the HTML is

<META http-equiv="Refresh" content="5; URL=http://www.new.site/page.html">

Where '5' means five seconds.

phpprogrammer

Dear frined,

the solution given by weekpacket is suggestable and good use that code

regards
bvsureshbabu

NoBullMan

Sorry for being a bit confused. I wanted to go to a different page ONLY if a certain condition was satisfied or certain value was returned by a function. It seems if I do a "Refresh" with "content=5", I will go to that page in 5 seconds, regardless.
I guess I can stick a javascript window.location in my PHP.
Some suggested to re-write the code. How would you logically set up the page if you wanted to achieve the functionality I described: to redirect the user to a different page IF certain condition is (or is not) satisfied.

csousley

You can write all the code you want before a header redirect in PHP, you just can't echo anything back to the browser or set a cookie and then redirect. So some if statements would be fine.

NoBullMan

Thanks. Sorry for being a bird-brain! This issue is really driving me nuts!

Here is the scanrio:
the user clicks on an item to add to his cart. This item, however, has a pre-requisite item that is not in the cart. I want to let the user know about the pre-req and give him the option of either adding the pre-req item (by clicking OK) or removing the item he has added (by clicking Cancel). I have to find out what the returned value is (which button is clicked) and redirect the user accordingly.

If you guys know of a way to do this, I would really, really appreciate it.

gersh

If you dont want to use the java script method for the redirect you could use php:

$url = 'index.php?flag=false';
die('<meta http-equiv="refresh" content="0;URL='.$url.'">');

NoBullMan

Thanks.
I am still trying to find out how to ask the user for confirmation and pass the result to the PHP file.
I need to be able to go to a different page depending on what the user clicks (OK or Cancel) and also how to create the confirmation dialog box inthe first place.

if (condition) {
open a dialog box and ask the user to click OK or Cancel
if OK is clicked, go to abc.php
if Cancel is clicked, go to def.php
}