How to make an IMC calculator?

Question

I’m trying to create functions without searching on the Internet, just with the notion of the things I’ve learned, but I’m not able to make a calculator, a broken number. What am I missing?

$peso = $_POST['peso'];
$altura = $_POST['altura'];

function imc($altura, $peso){
$altura = str_replace(',', '.', $altura);
$result = $altura * $altura / $peso;
return $result;

}

echo"seu imc é: " .imc($altura , $peso);
?>

Answer 1

IMC = weight in kg divided by height times height, which is the response of Caymmi.

But there are other operations that return the same result:

1 - using pow(x,y) function returns x high to the power of y, in the case of $squared height. See example in ideone

$peso = $_POST['peso'];
$altura = $_POST['altura'];

function imc($altura, $peso){
$altura = str_replace(',', '.', $altura);
$result = $peso/pow($altura, 2);
return $result;

}

echo"seu imc é: " .imc($altura , $peso);

2 - Inverse of a division. See example on ideone

could use too $result = 1/(pow($altura, 2)/ $peso); that would return the same result.

     pow($altura, 2)              $peso
1 ÷  _______________  =  1 x ________________ = $peso/pow($altura, 2)
         $peso                pow($altura, 2)

3 - From PHP 5.6 you may prefer to use the operator ** See example on ideone

$peso = $_POST['peso'];
$altura = $_POST['altura'];

function imc($altura, $peso){
$altura = str_replace(',', '.', $altura);
$result = $peso/$altura**2;
return $result;

}

echo"seu imc é: " .imc($altura , $peso);

the result can be formatted using the function number_format()

Answer 2

First you have to multiply height by height and then divide weight by height.

  function imc($altura, $peso){
$altura = str_replace(',', '.', $altura);
$altura = $altura * $altura;
$result = $peso / $altura;
return $result;}