Php Error Message On Invalid Input
I am new to php I am trying to print an error message If a person insert anything other then a real number in the field. I hope it make sense here is the code, and please describe
Solution 1:
<?php
$result = "";
class calculator
{
var $a;
var $b;
function checkopration($oprator)
{
switch($oprator)
{
case '+':
return $this->a + $this->b;
break;
case '-':
return $this->a - $this->b;
break;
case '*':
return $this->a * $this->b;
break;
case '/':
return $this->a / $this->b;
break;
default:
return "Sorry No command found";
}
}
function getresult($a, $b, $c)
{
$this->a = $a;
$this->b = $b;
return $this->checkopration($c);
}
}
$cal = new calculator();
if(isset($_POST['submit']))
{
$n1=$_POST['n1'];
$n2=$_POST['n2'];
$op=$_POST['op'];
if(is_numeric($n1)&&is_numeric($n2)){
$result = $cal->getresult($n1,$n2,$op);
}else{
$result="<p style='background-color:#FFCCCC'><b>ERROR: </b>Invalid input</p><br>";
}
}
?>
<form method="post">
<table align="center">
<tr>
<td><strong><?php echo $result; ?><strong></td>
</tr>
<tr>
<td>Enter 1st Number</td>
<td><input type="text" name="n1"></td>
</tr>
<tr>
<td>Enter 2nd Number</td>
<td><input type="text" name="n2"></td>
</tr>
<tr>
<td>Select Oprator</td>
<td><select name="op">
<option value="+">+</option>
<option value="-">-</option>
<option value="*">*</option>
<option value="/">/</option>
</select></td>
</tr>
<tr>
<td></td>
<td><input type="submit" name="submit" value="Submit"></td>
</tr>
</table>
</form>
Solution 2:
What you are looking for is the is_numeric()
function.
Take a look: http://php.net/manual/de/function.is-numeric.php
Solution 3:
using the is_numberic() function in php you can check if the inputed value is a number and if not we can return an error message
<?php
$result = "";
class calculator
{
var $a;
var $b;
function checkopration($oprator)
{
switch($oprator)
{
case '+':
return $this->a + $this->b;
break;
case '-':
return $this->a - $this->b;
break;
case '*':
return $this->a * $this->b;
break;
case '/':
return $this->a / $this->b;
break;
default:
return "Sorry No command found";
}
}
function getresult($a, $b, $c)
{
$this->a = $a;
$this->b = $b;
return $this->checkopration($c);
}
}
$cal = new calculator();
if(isset($_POST['submit']))
{
if(is_numeric($_POST['n1']) && is_numeric($_POST['n2'])){
$result = $cal->getresult($_POST['n1'],$_POST['n2'],$_POST['op']);
}else{
$result="please only insert numbers into the calculator";
}
}
?>
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