在php变量中添加html文本框值

Question

I want to sum values in a php variable from html text box my php code is as under

$total = 0;
$val2 = $_POST['val1'];
$total += val2;
echo "Sum of value is ". $total;

This is my HTML:

<form action="add.php" method="post" >
  <input type="text" name="val1" />
  ...
  ...

Answer 1

use Session

session_start();
$total = 0;
$val2 = $_POST['val1'];
$_SESSION["total"]+= $val2;
echo "Sum of value is ". $_SESSION["total"];

A session is a way to store information (in variables) to be used across multiple pages

Answer 2

Use sessions;

session_start();
$val2 = $_POST['val1'];
$total = 0;
if(isset($_SESSION['prev_sum'])){
    $total = $_SESSION['prev_sum'] + $val2;
}else{
    $total += $val2;
}
$_SESSION['prev_sum'] = $total;

echo "Sum of value is ". $total;

Answer 3

It should be something like

session_start();
$val1 = isset($_SESSION['val2']) ? $_SESSION['val2'] : 0 ;
$val2 = $_POST['val2'];
$total = $val1 + $val2;
$_SESSION['val2'] = $total;
echo "Sum of value is ". $total;

AND

<form action="add.php" method="post" >
    <input type="text" name="val1" value="<?php echo $_POST['val1'] ?>" />
    <input type="text" name="val2" />
....

Answer 4

$total+=$val2 refers to $total = $total + $val2 so the values are being summed up in the variable $total instead of $val2 . So replace $val2 in echo statement with $total .

Answer 5

you have to use sessions or database(which is not suitable for your current problem) for this because http is stateless protocol ie it cannot maintain its state so as soon as new request originates all the variables set to its default values

session_start();
$sum= 0;
$val2 = $_POST['val1'];
$_SESSION["sum"]+= val2;
echo "Sum of value is ". $_SESSION["sum"];