So, I made a calculator in PHP, which writes the result and that how much time used the calculator.
The first time I get some error, but when I click any submit button, the program work perfectly. What can I do with first time errors?
The program:
<html>
<body>
<div>
<?php
$using_calculator = $_POST['using_calculator'];
if(isset($_POST['plus'])){
$x = $_POST['number_1'];
$y = $_POST['number_2'];
$z = $x+$y;
$using_calculator++;
}else if(isset($_POST['minus'])){
$x = $_POST['number_1'];
$y = $_POST['number_2'];
$z = $x-$y;
$using_calculator++;
}else if(isset($_POST['multiplication'])){
$x = $_POST['number_1'];
$y = $_POST['number_2'];
$z = $x*$y;
$using_calculator++;
}else if(isset($_POST['division'])){
$x = $_POST['number_1'];
$y = $_POST['number_2'];
$z = $x/$y;
$using_calculator++;
}
?>
<form action="<?php echo $_SERVER['PHP_SELF'] ?>" method="POST">
<p>
First number: <input type="number" name="number_1"><br/>
Second number: <input type="number" name="number_2"><br/><br/>
<input type = "submit" name="plus" value="Plus">
<input type = "submit" name="minus" value="Minus">
<input type = "submit" name="multiplication" value="Multiplicate">
<input type = "submit" name="division" value="Divide">
<input type = "hidden" name="using_calculator" value="<?php echo $using_calculator; ?>">
</p>
</form>
<br>Result: <?php echo $z; ?>
<br>The calculator was used <?php echo $using_calculator; ?> times
</div>
</body>
I have to use hiddened input fields, but I can use functions and object. So what is the best way?
Its because first time variables(in your php code) is not isset. So it will display error. For example
So php will output error message first time. After submit this variables get initialized from POST. So to avoid this problem, modify the php code as shown below
<?php if(isset($_POST['using_calculator'])) { $using_calculator = $_POST['using_calculator']; if(isset($_POST['plus'])){ $x = $_POST['number_1']; $y = $_POST['number_2']; $z = $x+$y; $using_calculator++; }else if(isset($_POST['minus'])){ $x = $_POST['number_1']; $y = $_POST['number_2']; $z = $x-$y; $using_calculator++; }else if(isset($_POST['multiplication'])){ $x = $_POST['number_1']; $y = $_POST['number_2']; $z = $x*$y; $using_calculator++; }else if(isset($_POST['division'])){ $x = $_POST['number_1']; $y = $_POST['number_2']; $z = $x/$y; $using_calculator++; } } ?>