Displaying one record at a time in php [duplicate] - php

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What does the PHP error message “Notice: Use of undefined constant” mean?
I am trying to display one (record) question at a time in the same page. I put a condition at the beginning of the code to check if this is the first time the page loads, if it is, then display the first record. Otherwise, go to the "else" statement where the second record will be displayed. Every time a record is displayed, the counter increases by one ($i++). Also, I saved all the retrieved records in an array and reading the records one at a time from this array.
I don't know why I am getting errors here like the the following:
(1) Use of undefined constant i - assumed 'i'
(2) Undefined index: i
Does anyone know how to fix this problem?
Here is my code:
<?php
$f_name = $_SESSION['first_name'];
$l_name = $_SESSION['last_name'];
$arr_rows;
$i;
if (!isset($_POST['next']))
{ //if form is not submitted,
$command2 = "SELECT user_id FROM user_info WHERE user_info.first_name = '$f_name'
and user_info.last_name = '$l_name'";
$command1 = "SELECT * FROM topics, documents WHERE topics.topic_id =documents.topic_id";
$i=0; // Counter for the number of documents per topic
$userid = mysql_query($command2);
$results = mysql_query($command1);
$num=mysql_numrows($results);
//////////////
$arr_rows = array();
while( $row = mysql_fetch_array( $results ) )
$arr_rows[] = $row;
$arr = mysql_fetch_row($userid);
$id_user = $arr[0];
echo $f_name;
$relevancy = "This is the first time to load this page";
$f1=$arr_rows[i]['topic_name'];
$f1_topic_description=$arr_rows[i]['topic_descrip'];
$f1_doc_content=$arr_rows[i]['doc_content'];
++$i;
}
else
{ //otherwise,
$relevancy = $_POST['RadioGroup1'];
$f1=$arr_rows[i]['topic_name'];
$f1_topic_description=$arr_rows[i]['topic_descrip'];
$f1_doc_content=$arr_rows[i]['doc_content'];
++$i;
}
?>

Answer 1

$f1=$arr_rows[i]['topic_name'];
$f1_topic_description=$arr_rows[i]['topic_descrip'];
$f1_doc_content=$arr_rows[i]['doc_content'];
should be
$f1=$arr_rows[$i]['topic_name'];
$f1_topic_description=$arr_rows[$i]['topic_descrip'];
$f1_doc_content=$arr_rows[$i]['doc_content'];
You were missing the dollar sign on the variable "i".

Answer 2

PHP doesn't store your variables over to the next request.
You can add the counter information ($i) either to a session variable, cookie, or request parameter. Otherwise your $i will always start again from zero.

Answer 3

When using "i" to specify an index in your arrays, you are missing the $. For example:
$f1=$arr_rows[i]['topic_name'];
$f1_topic_description=$arr_rows[i]['topic_descrip'];
$f1_doc_content=$arr_rows[i]['doc_content'];
should read
$f1=$arr_rows[$i]['topic_name'];
$f1_topic_description=$arr_rows[$i]['topic_descrip'];
$f1_doc_content=$arr_rows[$i]['doc_content'];

Answer 4

You missing the $ before the variable name. Check through your code and replace i with $i.

Answer 5

The error is here I think... replace i with $i so you're actually calling your variable
$f1=$arr_rows[$i]['topic_name'];
$f1_topic_description=$arr_rows[$i]['topic_descrip'];
$f1_doc_content=$arr_rows[$i]['doc_content'];