Equation breakdown

[bukwus]

Hi

 

I have built a series of forms with PHP and have been using SESSIONS to carry values from one to another. In one, the value of a variable is determined by adding the values of several other variables together:

$totalFixed = $fixedCost1 + $fixedCost2 + $fixedCost3 + $fixedCost4 + $fixedCost5;

This equation is working fine on that page. I then place the value of $totalFixed in a SESSION variable:

$_SESSION['totalFix']=$totalFixed;

I then assign this SESSION variable's value to a new variable on another page in the series:

$dataValue[4] = $_SESSION['totalFix'];

The number displays fine on this page as well. However, when the value is above 1,000 and I try to subtract another number from it, it ignores everything to the right of the comma. For example, if $dataValue[4] is 10,132 and $dataValue[5] is 25 and I subtract $dataValue[4] from $dataValue[5], the result is -15.

Does anyone know the reason for this?

Many thanks,

Andy

[xyph]

Commas are added for human readability. They do not exist in computing. You need to remove these commas before attempting to perform arithmetic operations on the values.

 

str_replace might help with this.

 

Also, you need to be careful passing form data through sessions. What happens when you get half way through the form, open a new tab, and access the same form, or perhaps use a multi-page form with similar-named values?

In order to keep the value unique to the request, you need to create a unique token that gets passed through a hidden field in the form. You then use the token to store the data in a unique location within your session. $_SESSION['formData'][$token]...

[smerny]

where is it getting the value with the commas in the first place? if you are storing numeric values you might as well store them as a number (without commas).

 

if you want to have commas in output, i'd still store without and just use number_format() when you are going to echo something

[bukwus]

Thank you everyone. This was very helpful.