Stumped by loop output

[tovince]

Hi Everyone:

Can't get this loop to do what I want.

Here's what's happening:

page1.php has a form that asks users "How many chapters are in this book?" This value is stored in $book_numofchapters.

User enters a value--say 3, for this example--clicks next, goes to page2.php.

page2.php sets $_SESSION['book_numofchapters'] to equal $book_numofchapters. So far so good. Everything works.

page2.php then uses a loop to present the user with another form that displays the same number of text boxes as in $book_numofchapters--that's 3, in this example. Everthing is working fine up to this point. The user then enters each chapter's title into its own text box. The text boxes are generated in the loop and each one gets its own unique name based upon the loop iteration. In the loop, the text box names look like this:

name=\"book_chaptertitle_$i\"

(Thanks Dead Fly for helping me get this one to work).

page3.php then gets the number of chapters from the session and the form variables from page2.php just fine. If I put something like

echo $book_chaptertitle_1;

on page3.php, I get the value I'm looking for--in this example it could be Book Chapter One.

One of the things I want page3.php to do is put each book chapter title into its own session variable.

However, I can't just say

$_SESSION['$book_chaptertitle_1'] = $book_chaptertitle_1;

etc., because page3.php can't be hardcoded to know how many chapters a person will enter on page1.php. page3.php needs to loop through the total number of book chapters and enter each of the book chapter titles from page2.php into their own session variables.

Okay, so I got the loop to work--up to a point. Here's what I wrote on page3.php to test and see if that page was getting the correct values from page2.php:

for ($i=1; $i<=$_SESSION['book_numofchapters']; $i++){
echo $book_chaptertitle_1;
}

When I write the loop as above, it displays the correct value for $book_chaptertitle_1 which in this example is Book Chapter One, and it displays it the correct number of times stored in $_SESSION['book_numofchapters'].

However, I need it to be fancier. I need the loop to iterate through each value from page2.php and store those values in their own session variables. I tried this:

$bct = "\$book_chaptertitle";
for ($i=1; $i<=$SESSION['book_numofchapters']; $i++){
$x = $bct . $i;
$SESSION['$x'] = $x;
$r = $SESSION['$x'];
echo $r;
}

I put the echo line in there for testing purposes to see if I was indeed getting the value I want. I'm close, but not close enough!
The value that gets output as $r is the literal string "$book_chaptertitle_1" instead of "Book Chapter One".

How can I get $r to equal the value stored in $book_chaptertitle_1?

I feel like I'm really close, but everything else I try keeps giving me the string "$book_chaptertitle_1" instead of the stored value.

Thanks for your help!

--Vince

[TTT]

just quessing, didn't test
$bct = "\$book_chaptertitle";
for ($i=1; $i<=$SESSION['book_numofchapters']; $i++){
$x = $bct . $i;
$SESSION['$$x'] = $$x;
$r = $SESSION['$$x'];
echo $r;
}

[tovince]

TTT:

Thanks for the quick response!

Unfortunately, it didn't work.

Here's what you suggested:

$bct = "\$book_chaptertitle";
for ($i=1; $i<=$SESSION['book_numofchapters']; $i++){
$x = $bct . $i;
$SESSION['$$x'] = $$x;
$r = $SESSION['$$x'];
echo $r;
}

This changed the output of $r from

$book_chaptertitle_1

to

$$book_chaptertitle_1

I'll take any other ideas you might have.

Thanks again for giving it a shot.

--Vince

[Shrike]

for ($i=1; $i<=$_SESSION['book_numofchapters']; $i++){ 
  echo $_SESSION["book_chaptertitle_$i"] = $book_chaptertitle."_".$i; 
}
There are a few things you could do to make a tidier data structure. I think I would do this:
[code=php]
page1.php - Do as you have done

page2.php
When writing the session, write it as

$_SESSION['book_numofchapters'] = array();

Then create each text field as you have done, but with the name "bookchapters[]":
<input type=\"text\" name=\"bookchapters[]\">


page3.php
$_SESSION['book_numofchapters'][] = $_POST['bookchapters'];

So you have an array in the session referred to as book_numofchapters, which contains all of the fields from page2.php. You can get the actual number of chapters with count($_SESSION['book_numofchapters']). Using [] in the text field name adds each successive field with the same name to an array which can be passed over HTTP. Neat huh 🙂

It would look something like

$_SESSION['book_numofchapters'] = array( "title1", "title2", "title3");

HTH and code is untested 🙂

[tovince]

Shrike:

I tried both of the things you suggested.

First I tried:
for ($i=1; $i<=$SESSION['book_numofchapters']; $i++){

echo $SESSION["book_chaptertitle$i"] = $book_chaptertitle."".$i;

}

The output for this was the literal string "_1" not the value in "book_chaptertitle_1" which would be something like "Book Chapter One"

I then tried your array suggestion. I'm guessing I did something wrong, because when I entered "4" in the form field that asked how many chapters there are in the book, and then clicked the Next button on the form, I got 843 numbered text boxes to enter chapter titles! That was too funny. I'm sure I screwed that up somehow. I'll keep trying to fiddle with the array version you have suggested.

However, this leads me to another question, which is really the same question just put differently. Is there a "best method" to do the following?

1. Collect a value from a form text field on page1.php.
2. Put the value in a session on page2.php, and then use the value on page2.php to present users with the same number of text fields stored in the value.
3. Take the values entered into the new text field on page2.php, send them to page3.php and put each one in its own session. But only create the exact same number of sessions as in the value collected from page1.php

I'm guessing the array methodology you suggested might be
the best solution, but I can't get it to work . . . yet. I'll keep trying.

Thanks for your help!

--Vince

[Shrike]

Ok here's some example code. Sorry for the formatting, I used tabs and they don't display well on this board.

<?php

if(isset($_POST['numchapters'])){
	getChapterTitles();
}elseif(isset($_POST['displayresults'])){
	displayResults();
}else{
	getNumChapters();
}

function getNumChapters(){
	print("<form method=\"POST\" action=\"test1.php\">\n
		Enter number of chapters: <input type=\"text\" name=\"book_numofchapters\">\n
		<input type=\"hidden\" name=\"numchapters\" value=\"1\"><br>\n
		<input type=\"submit\" name=\"submit\">
	");
}

function getChapterTitles(){
	print("<form method=\"POST\" action=\"test1.php\">\n");
	for($i = 1; $i <= $_POST['book_numofchapters']; $i++){
		print("Enter chapter title $i: <input type=\"text\" name=\"book_chaptertitle[]\"><br>\n");
	}
	print("<input type=\"hidden\" name=\"displayresults\" value=\"1\"><br>\n
		<input type=\"submit\" name=\"submit\">\n
		</form>
	");

}

function displayResults(){
	session_start();
	$_SESSION['book_numofchapters'] = $_POST['book_chaptertitle'];
	print("The book has ".count($_SESSION['book_numofchapters'])." chapters. They are:<br><br>");
	foreach($_SESSION['book_numofchapters'] as $title){
		print($title."<br>");
	}
	print("<br>Thanks for listening");
}

?>

The above code works on my machine. I made a few minor errors in my first post. Firstly theres no need to set the array in the second phase of the code. Secondly, the session array should be added as:
$SESSION['book_numofchapters'] = $POST['book_numofchapters']

Thirdly theres no real need to involve sessions until the final phase, unless you envision people completing parts 1 and 2, doing something else then coming back to phase 3.

Finally, theres no need to use separate files for this code 🙂

HTH

[tovince]

Thanks for getting back to my question so quickly.
I won't get a chance to take a closer look
at your suggested solution until later this evening.
I'll work with it at that time, and then I'll
let you know how it goes.

Thanks again.

--Vince

[mtimdog]

The above was close, but this should work

<?php

$bct = "\$book_chaptertitle_"; 
for ($i=1; $i<=$_SESSION['book_numofchapters']; $i++){ 
$x = $bct . $i; 
$_SESSION[$x] = $$x; 
$r = $_SESSION[$x]; 
echo $r; 
//or you could just echo $_SESSION[$x] since r is redundant
} 

?>

[tovince]

mtimdog and Shrike:

I just tried mtimdog's suggestion because it was a quick edit for me. It didn't give me what I expected.

Shrike, I still plan to get to your version later tonight. I'll need more time to figure it out and attempt to implement it.

I still don't understand, though, why it's not working.

Here's what mtimdog suggested.

<?php

$bct = "\$book_chaptertitle";

for ($i=1; $i<=$SESSION['book_numofchapters']; $i++){

$x = $bct . $i;

$SESSION[$x] = $$x;

$r = $SESSION[$x];

echo $r;

//or you could just echo $_SESSION[$x] since r is redundant
}

?>

So, if page3.php has the above loop, and page2.php is successfully passing variables to page3.php, why does this loop not give me the output I think I'm going to get? When I implement the above code, I get no output at all.

I know page3.php is getting the variables from page2.php because if, on page3.php, I simply put

echo $book_chaptertitle_1;

I get the output I expect, say "Book Chapter One".

However, if, on page3.php, I use a loop like the one suggested by mtimdog, I either get no output at all or I get the literal string "$book_chaptertitle_1" which, obviously, isn't what I want stored in the session. I want "Book Chapter One" in the session because that's what I eventually want to send to the DB (a couple of pages later).

But I don't see why it's not working.

Here's the loop again with some new comments by me explaining how I understand it to be working.

<?

// this is on page3.php
// at this point, I know page2.php
// is successfully passing its form data because
// if I just put

echo $book_chaptertitle_1;

// the correct value is output on page3.php

// now I'll start with the loop
// this sets the prefix I want used in the loop
$bct = "\$book_chaptertitle_";

// now I start the loop
for ($i=1; $i<=$_SESSION['book_numofchapters']; $i++){

// I know that at this point the loop is working correctly
// because if I just put something like
echo "house";
//at this point I'll get 4 "house's" if

// $_SESSION['book_numofchapters'] equals "4"

// but now I want to concatenate $bct and $i
// so I have this
$x = $bct . $i;

// at this point in the loop, $x is apparently equal
// to the literal string "$book_chaptertitle_1"
// instead of the value "Book Chapter One"
// that was sent over from page2.php
// Now, I thought this fix by mtimdog
$_SESSION[$x] = $$x;
// might work because it adds the "$" before $x
// which I thought meant "make whatever literal
// string you have in "$x" into a variable.
// but that's not what's happening.

// you can ignore the rest of this for now.
// I was just using this echo stuff to see
// what value was being put in the session.
$r = $SESSION[$x];

echo $r;

//or you could just echo $SESSION[$x] since r is redundant
}

?>

Well, anyway, I'm neurotic.
Thanks for bearing with me on this one.
Like I said, I'll try Shrike's suggestion with functions
later tonight.

--Vince

[mtimdog]

Sorry about that, take out the \$ to make

$bct = "book_chaptertitle_";

at the top...then it looks like it should work from there.

[tovince]

First, I want to thank Shrike and mtimdog for their generous help. I really appreciate your responses to my questions.

Second, mtimdog, the last post you made worked. After I removed the \$ from the variable definition, everything worked great.

Third, Shrike, the script you posted--the one with the functions--has totally opened my eyes. I can't thank you enough.

Fourth, this is a pretty long post from this point on. It's just me walking through Shrike's script to make sure I actually understand how it works; so, if you don't want to read any further, don't bother.

<?php

/
All of the following code came from Shrike
on the phpbuilder.com Coding
message board on 24 Feb 04.

Remember, the rest of this is pretty long. All of my comments/remarks
are in the comment lines peppered around the code.

I'm writing this because I just want to make sure I understand
exactly what Shrike accomplished. If you bother to read through
all these comments, my only question is, Am I understanding this stuff?

Okay, first, up to this point, I had never really understood
how functions work, but now, looking at Shrike's code, I think I
finally get it. Well, let's see.
/

/
So, this if/elseif/else statement is saying
"If the browser is reading this page, and there's a variable
named numchapters attached to the URL, and that variable
has a value of 1, then do everything in the getChapterTitles() function.
If there's no numchapters variable appended to the URL but there
is a displayresults variable, and the displayresults variable has
a value of 1, then do everything in the displayResults()
function. Finally, if the browser comes to this page and there
are no variables appended to the URL, just do everything in the
getChapterTitles() function."

How am I doing?

*/
if(isset($POST['numchapters'])){
getChapterTitles();
}elseif(isset($POST['displayresults'])){
displayResults();
}else{
getNumChapters();
}

/
This getNumChapters() is the function that comes in to play the first time
a user comes to "test1.php". If I understand correctly,
the form's action could submit to "fredwilmaanddino.php" or
whatever name I want to give the page, as long as every
form on this page refers to the same name, right?

In getNumChapters() the hidden form field is there simply
to post a value of 1 to the URL so that the if/elseif/else
statement, above, can figure out whether or not a value
has been entered into the book_numofchapters text field.
/
function getNumChapters(){
print("<form method=\"POST\" action=\"test1.php\">\n
Enter number of chapters: <input type=\"text\" name=\"book_numofchapters\">\n
<input type=\"hidden\" name=\"numchapters\" value=\"1\"><br>\n
<input type=\"submit\" name=\"submit\">
");
}

/
The getChapterTitles() function comes in to play only
if the numchapters value of 1 has been appended to the
URL.
*/
function getChapterTitles(){
print("<form method=\"POST\" action=\"test1.php\">\n");

/* 
* The $_POST['book_numofchapters'] part of this for loop says 
* "Okay, go look in the URL for the value stored in book_numofchapters."
* Then the loop begins and runs, starting at 1 and continuing for the 
* value in $_POST['book_numofchapters']. So, if the value 
* in $_POST['book_numofchapters'] was equal to 4, the loop would
* run 4 times. I know, I know. Duh. But writing through it helps me get it.
*/
for($i = 1; $i <= $_POST['book_numofchapters']; $i++){ 
	/* The $i on this next line simply says,
	* "Whatever $i is equal to at this point in the loop,
	* put that value here."
	* 
	* When the name attribute is set to book_chaptertitle[]
	* those brackets say, "Put all the stuff you're about to
	* get into an array because somebody, somewhere is going
	* to want all this data!" I had no idea setting up an array
	* was that easy. This was an epiphany for me.
	*/
    print("Enter chapter title $i: <input type=\"text\" name=\"book_chaptertitle[]\"><br>\n"); 
} 
/* 
* The hidden value displayresults is the one that tells 
* the form's action page, "Hey! There's data in this form so
* come and get it!" So if diplayresults is in the URL,
* then the diplayResults() function will execute.
*/
print("<input type=\"hidden\" name=\"displayresults\" value=\"1\"><br>\n 
    <input type=\"submit\" name=\"submit\">\n 
    </form> 
"); 

}

/
Okay, so now the displayResults() function.
This one opens up a session.
It then takes the value from $POST['book_chaptertitle']
and puts it in a session named $SESSION['book_numofchapters'].

If I understand this correctly, the ENTIRE array of chaptertitles
is now stored in ONE session variable named $SESSION['book_numofchapters'].
So, if the book had 30 chapters, all 30 chapter titles would be stored
in one session variable, right? The way I was doing it would
have created a single session variable for each chapter title.
That now seems like a resource-hog-way of doing things. This
way--the way Shrike has done it with an array--makes a lot more
sense.

The count($SESSION['book_numofchapters']) just counts however
many elements there are in the array, right?

Finally, the foreach loop is essentially saying, "Break up the array stored
in $SESSION['book_numofchapters'], give each element a variable name of $title,
and then print each $title--each one of the array elements--to the page."
When I'm ready to add these chapter titles to the database, I could
then use a similar foreach loop, but instead of putting a print line
inside the loop, I would just put the appropriate SQL Insert line.
Am I understanding this correctly? The foreach loop seems pretty
powerful in this way. All new to me.
*/
function displayResults(){
session_start();
$SESSION['book_numofchapters'] = $POST['book_chaptertitle'];
print("The book has ".count($SESSION['book_numofchapters'])." chapters. They are:<br><br>");
foreach($_SESSION['book_numofchapters'] as $title){
print($title."<br>");
}
print("<br>Thanks for listening");
}

?>

Well, as Shrike said in that last print line,
Thanks for listening. And if you got this far,
I'd email you a beer, but, alas, no one has figured
out how to make such crucial strides in electronics.
They're all caught up with "cell phones" and "PDAs."
Whose working on the real conundrums like
emailing beer?

--Vince

[Shrike]

Glad to help, it was only 10 mins rough draft so perhaps it could be refined a bit.

You got everything right on the functionality 🙂