Feet to meters & opposite

[scialom]

Hi,
I've developed an application that does a lot of calculation based on meters
Now the client is asking to input all the date in feet and inches
So I wrote two functions to convert feet to meter and meter to feet
but this create an inaccurate results.

 function convert2feet($num){
          $feet = floor( $num / 0.3048 );
          $inches = ($num - 0.3048*$feet) / 0.0254;
          $fi = $feet."' ".round($inches,0)."\"";

      return $fi;
}
function convert2meter($num){
  $numbers = explode("'",$num);
  $feet = intval($numbers[0]);
  $inches   = str_replace('"','',$numbers[1]);
  $meter = ($feet* 0.3048)+($inches*0.0254) ;
  return $meter;
}

Any idea how I can overcome this problem?
thanks!

[Derokorian]

I don't understand what your problem is, however here are my functions, and their comparison to yours:

<?php

function meterToFeetInches($meter,$precision = 0) {
   $inches = $meter * 39.3700787;
   $feet = floor($inches/12);
   $inches = round($inches - (12*$feet),$precision);
   return $feet . "'" . $inches .'"';
}

function feetInchesToMeter($feetinches,$precision = 2) {
   list($feet,$inches) = explode("'",$feetinches);
   $inches = preg_replace('/[^0-9.]/','',$inches);
   $inches = $inches + ($feet * 12);
   return round($inches / 39.3700787,$precision);
}

function convert2feet($num){
   $feet = floor( $num / 0.3048 );
   $inches = ($num - 0.3048*$feet) / 0.0254;
   $fi = $feet."' ".round($inches,0)."\"";

   return $fi;
}
function convert2meter($num){
  $numbers = explode("'",$num);
  $feet = intval($numbers[0]);
  $inches   = str_replace('"','',$numbers[1]);
  $meter = ($feet* 0.3048)+($inches*0.0254) ;
  return $meter;
}

$fi = "12'10\"";
$m = 3.3;

echo "Dero's:<br>";
echo $fi.' = '.feetInchesToMeter($fi).'m<br>';
echo $m.'m = '.meterToFeetinches($m).'<br><br>';

echo "Scialom's:<br>";
echo $fi.' = '.convert2meter($fi).'m<br>';
echo $m.'m = '.convert2feet($m);

Which outputs:

Dero's:
12'10" = 3.91m
3.3m = 10'10"

Scialom's:
12'10" = 3.9116m
3.3m = 10' 10"

[scialom]

Thanks I used your functions and still have problems:
5'0" = 1.52
1.52 = 4' 12"

[bradgrafelman]

What are the problems? The results you posted look correct (following basic rounding rules).

EDIT: D'oh! Saying 4'12" is a bit odd, isn't it?

[Derokorian]

Ok added checking for 12inches to add to the feet:

function meterToFeetInches($meter,$precision = 0) {
   $inches = $meter * 39.3700787;
   $feet = floor($inches/12);
   $inches = round($inches - (12*$feet),$precision);
   if( $inches == 12 ) { $feet++; $inches = 0; }
   return $feet . "'" . $inches .'"';
}

However I don't see the error with 5'0" -> 1.52 as that's what it is (if you need more decimal places, change the precision argument of the function).

[Derokorian]

Of course if you did meterToFeetInches(1.52,2) you would get 4'11.84" because its actually not a full 5 feet (but very near).

[scialom]

thanks the error was with the converting back to the inches which you nicely solved!