Preserve form values from page to page - php

Question

I have two PHP pages from one I input the year and after submitting year value goes in next page via form input as in image enter image description here
image just after clicking the submit button of first page
code for the first page is
<div class="col-sm-12" style="background-color:lavender;">
<form method="post" action="next.php">
<table id="emi" width="100%">
<tr>
<td width="100%">
<div align="center"><b>
<h3> Enter Fiancial Information:</h3>
</b> </td>
<table width="100%" border="0" id="emi">
<tr>
<td><strong>First Calender Year of DATA! ( i.e. 1999 ) </strong></td>
<td><input type="text" class="form-control" placeholder="Enter the First Assesment Year" name="year" pattern="\d*" maxlength="4"></td>
<td><input type="submit" value="Go" name="submit"class="btn btn-success"></td>
</tr></table>
</table></form>
</table>
I have two PHP pages from one I input the year and after submitting year value goes in next page via form input as in image enter image description here
In next page I have one form input also and after input the values in next page and after clicking compute button the value of year which we call from page one disappear. As shown in image
Image after clicking the compute button on next.php
code for the next.php which is called after the first page is
<?php
error_reporting(0);
$year=$_REQUEST['year'];
$x=$year+1;
$y=$x+1;
?>
<table id="emi"width="100%">
<tr>
<td width="40%"><strong>INCOME STATEMENT
</strong></td>
<td width="20%"><strong> 31-03-<?php echo $year;?></strong></td>
<td width="20%"><strong> 31-03-<?php echo $x?></strong></td>
<td width="20%"><strong> 31-03-<?php echo $y?></strong></td>
</tr>
<form method="post" action="<?php echo $_SERVER['PHP_SELF'];?>">
<div class="form-group">
<table id="emi" width="100%">
<tr>
<td width="40%"><strong>Sundray Creditors</strong></td>
<td width="20%"><input type="text" name="a1" size="8" class="form-control"></td>
<td width="20%"><input type="text" name="suncre" size="8" class="form-control"></td>
<td width="20%"><input type="text" name="inv" size="8" class="form-control"></td>
</tr>
<tr>
<td width="40%"><strong>Sundray Creditors</strong></td>
<td width="20%"><input type="text" name="a2" size="8" class="form-control"></td>
<td width="20%"><input type="text" name="suncre" size="8" class="form-control"></td>
<td width="20%"><input type="text" name="inv" size="8" class="form-control"></td>
</tr>
</table>
<table id="emi" width="100%">
<tr>
<td colspan="3">
<center>
<input type="submit" value="Compute" name="submit"class="btn btn-success"></center>
</td>
</tr>
</table>
</form>
<?php
error_reporting(0);
if($_SERVER['REQUEST_METHOD']=="POST"){
$a=$_POST['a1'];
$b=$_POST['a2'];
echo $a+$b;
}?>
I have only call the value of year then plus one in it as you see 2000 2001 2002 to next page and when I enter the value of sundry it disappears the value of year and we get only plus means value of year become 0 after clicking the compute button.

Answer 1

When you submit the form on the second page via your "Compute" button $_REQUEST['year'] is no longer set because it was from the previous request.
One way around this would be to add a hidden input field which stores the $_REQUEST['year'] value for the next request.
Something like this should work:
<input type="hidden" name="year" value="<? echo $_REQUEST['year']; ?>">

Answer 2

replace your next.php with this code
<?php
error_reporting(0);
$year=$_REQUEST['year'];
if($year==null){
$year=$_POST['year'];
}
$x=$year+1;
$y=$x+1;
?>
<table id="emi"width="100%">
<tr>
<td width="40%"><strong>INCOME STATEMENT
</strong></td>
<td width="20%"><strong> 31-03-<?php echo $year;?></strong></td>
<td width="20%"><strong> 31-03-<?php echo $x?></strong></td>
<td width="20%"><strong> 31-03-<?php echo $y?></strong></td>
</tr>
<form method="post" action="<?php echo $_SERVER['PHP_SELF'];?>">
<div class="form-group">
<table id="emi" width="100%">
<tr>
<td width="40%"><strong>Sundray Creditors</strong></td>
<td width="20%"><input type="text" name="a1" size="8" class="form-control"></td>
<td width="20%"><input type="text" name="suncre" size="8" class="form-control"></td>
<td width="20%"><input type="text" name="inv" size="8" class="form-control"></td>
</tr>
<tr>
<td width="40%"><strong>Sundray Creditors</strong></td>
<td width="20%"><input type="text" name="a2" size="8" class="form-control"></td>
<td width="20%"><input type="text" name="suncre" size="8" class="form-control"></td>
<td width="20%"><input type="text" name="inv" size="8" class="form-control"></td>
</tr>
</table>
<table id="emi" width="100%">
<tr>
<td colspan="3">
<center>
<input type="hidden" id="year" name="year" value="<?php echo($year);?>">
<input type="submit" value="Compute" name="submit"class="btn btn-success"></center>
</td>
</tr>
</table>
</form>
<?php
error_reporting(0);
if($_SERVER['REQUEST_METHOD']=="POST"){
$a=$_POST['a1'];
$b=$_POST['a2'];
echo $a+$b;
}?>