Testing an Online Calculator

[Bemlikanz]

Im trying to make a calculator, so i'll just upload it here to test.

$opera1 = $_GET['operando1']; 
$opera2 = $_GET['operando2']; 
$result = NULL; 
$erro = NULL; 
/* switch ($operador) { 
        case "+": 
            $result = $opera1 + $opera2; 
            break; 
        case "-": 
            $result = $opera1 - $opera2; 
            break; 
        case "*": 
            $result = $opera1 * $opera2; 
            break; 
        case "/": 
            $result = $opera1 / $opera2; 
            break;     
    } */ 
if (isset($_GET['operador+'])){ 
    $result = $opera1 + $opera2; 
} elseif (isset($_GET['operador-'])){ 
    $result = $opera1 - $opera2; 
} elseif (isset($_GET['operador*'])){ 
    $result = $opera1 * $opera2; 
} elseif (isset($_GET['operador/'])){ 
    $result = $opera1 / $opera2; 
    if ($opera2 === "0"){ 
        $erro = "Não se pode dividir algo por zero"; 
    } 
} elseif (isset($_GET['limpa'])){ 
    $result = NULL; 
    $opera1 = NULL; 
    $opera2 = NULL; 
}  

<frameset cols="80%, *" frameborder="1">
<frame>
<table border="2">
<form action="#" method="GET" >
	
<tr> <td> Somar <input type="submit" value="+" name="operador+"/></td>
	<td> Subtrair	<input type="submit" value="-" name="operador-"  /> </td>
	<td> Multiplicar	<input type="submit" value="*" name="operador*"  /> </td>
	<td> Dividir	<input type="submit" value="/" name="operador/"  /> </td>
	<td> Limpar	<input type="submit" value ="C" name="limpa"     /> </td> </tr>
		
	<tr> <td> 	<input type="text" size="10" maxlength="8" 	name="operando1" value="[PHP] echo $opera1 [/PHP]"		 /> </td> </tr>
	<tr><td> 	<input type="text" size="10" maxlength="8" name="operando2"		value="[PHP] echo $opera2 [/PHP]"	 /> </td> </tr>
	<tr><td> 	<input type="text" size="10" maxlength="8" name="resultado"	readonly value=" [PHP]echo $result[/PHP] " /> </td> </tr> 
</form>
</table>
</frame>
<frame>
Barra Lateral 
</frame>
</frameset>

[Zangeiti]

Im no coder hear but it looks fine to me because you can pop up your computer calculator and inspect element and the coding looks the same also this should probably be in computer section.

[Badpaladin]

Is the goal here to restrict user input such that they can only enter a left value, right value, and binary operator?

If not, you're going to need significantly more logic to handle different kinds of input. An easy solution would be to parse the input into postfix notation (Dijsktra's Shunting-Yard is a good choice) and then use a stack to evaluate postfix representation of the expression.