BMI Calculation in php

[mglover88]

Hi all,

 

I need to add a BMI (Body Mass Index) calculator to my site. The calculator works but when the page is first opened (before any info has been put into the calculator) the page displays the message "Notice: Undefined variable: bmi in C:\wamp\www\bmiCalculator.php on line 242" where the final calculation will be displayed.

 

I was just wondering if anyone knows how to fix this or if it's anything at all to do with the fact I am using it on a testing server at the moment?

 

The code I am using to power the equation is as follows:

<?php
if ((isset($_POST["done"])) && ($_POST["done"] =="y")){

$height = ((12 * $_POST["feet"]));
if ((isset($_POST["inches"])) && ($_POST["inches"] > 0)){
$height = $height + $_POST["inches"];
}

$bmi = ($_POST["lbs"]) / ($height * $height) * 703;

}
?>

 

And the actual calculator is in a table as follows:

<form method="post" name="bmiForm" action="<?php echo $_SERVER['PHP_SELF']; ?>" >
  ...
    <tr>
      <td><label>
      <input type="submit" name="Submit" value="Calculate" tabindex="40" />
      <input name="done" type="hidden" value="y" />
  ...
    <tr>
      <td>your BMI is:</td>
      <td class="bold"><?php echo round($bmi,1); ?></td>
      <td> </td>
    </tr>
  </table>
  </form>

 

Thanks in advance for any help.

 

 

[AMcHarg]

Just define $bmi at the top of your page:

$bmi = '';

 

An undefined variable is a variable that you are trying to use but hasn't been given a value.

[mglover88]

Awesome. Thanks very much, it's always something simple that I miss.

[mglover88]

Actually, no that's not working. The notice that the variable is undefined goes away when I first open the page, but the calculator doesn't work now as it is taking the value to always be $bmi = '' so it displays 0 whatever information I put into the calculator.

[micah1701]

add $bmi=""; AFTER as the second condition of your IF statement...

 

<?php
<?php
if ((isset($_POST["done"])) && ($_POST["done"] =="y")){

$height = ((12 * $_POST["feet"]));
if ((isset($_POST["inches"])) && ($_POST["inches"] > 0)){
$height = $height + $_POST["inches"];
}

$bmi = ($_POST["lbs"]) / ($height * $height) * 703;

}else{
$bmi = "";
}
?>

[mglover88]

Ah ok , that's definitely working fine now. Thanks a lot, really appreciate it.

[colap]

Just define $bmi at the top of your page:

$bmi = '';

 

An undefined variable is a variable that you are trying to use but hasn't been given a value.

Why is it necessary to define $bmi="" ; at top?