PHP Warning Division by zero

Question

I m learning php and built an experimental form-based calculator  also using html  amp  POST method  that returns values to a table  The calculator is functional when I enter my values and click submit  but I keep getting two  Division by zero  errors on the last line when I first run the code  I can t seem seem to find a logical solution or explanations when searching here or via Google  Any explanation you can provide to a newb will be appreciated      lt  php   error reporting E ALL   E NOTICE      calculate the difference in price   itemQty     POST  num1      itemCost     POST  num2      itemSale     POST  num3      shipMat     POST  num4      diffPrice    itemSale -  itemCost    actual     diffPrice -  shipMat     itemQty    diffPricePercent      actual   100     itemCost     itemQty      gt

User · Answer

A lot of the answers here do not work for (string)"0.00".

Try this:

if (isset($_POST['num1']) && (float)$_POST['num1'] != 0) {
  ...
}

Or even more strict:

if (isset($_POST['num1']) && is_numeric($_POST['num1']) && (float)$_POST['num1'] != 0) {
  ...
}

User · Answer

If a variable is not set then it is NULL and if you try to divide something by null you will get a divides by zero error

User · Answer

You can try with this  You have this error because we can not divide by  zero   0  value  So we want to validate before when we do calculations   if   itemCost    0  amp  amp   itemCost    NULL  amp  amp   itemQty    0  amp  amp   itemQty    NULL          diffPricePercent      actual   100     itemCost     itemQty      And also we can validate POST data  Refer following   itemQty   isset   POST  num1        POST  num1     0    itemCost   isset   POST  num2        POST  num2     0    itemSale   isset   POST  num3        POST  num3     0    shipMat   isset   POST  num4        POST  num4     0

User · Answer

try this  if isset  itemCost         amp  amp  isset  itemQty                diffPricePercent      actual   100     itemCost     itemQty    else       echo  either of itemCost or itemQty are null

User · Answer

when my divisor has 0 value  if   divisor    0         divisor   1

User · Answer

You need to wrap your form processing code in a conditional so it doesn t run when you first open the page  Something like so   if   POST  num1    gt  0  amp  amp    POST  num2    gt  0  amp  amp    POST  num3    gt  0  amp  amp    POST  num4    gt  0       itemQty     POST  num1       itemCost     POST  num2       itemSale     POST  num3       shipMat     POST  num4        diffPrice    itemSale -  itemCost     actual     diffPrice -  shipMat     itemQty     diffPricePercent      actual   100     itemCost     itemQty

User · Answer

diffPricePercent      actual   100     itemCost     itemQty     itemCost and  itemQty are returning null or zero  check them what they come with to code from user input  also to check if it s not empty data add   if   empty   POST  num1            itemQty     POST  num1        and you can check this link for POST validation before using it in variable   https   www virendrachandak com techtalk php-isset-vs-empty-vs-is null

User · Answer

Try using   var      val1    val2

User · Answer

If it shows an error on the first run only  it s probably because you haven t sent any POST data  You should check for POST variables before working with them  Undefined  null  empty array  empty string  etc  are all considered false  and when PHP auto-casts that false boolean value to an integer or a float  it becomes zero  That s what happens with your variables  they are not set on the first run  and thus are treated as zeroes   10    unsetVariable   becomes  10   0   Bottom line  check if your inputs exist and if they are valid before doing anything with them  also enable error reporting when you re doing local work as it will save you a lot of time  You can enable all errors to be reported like this  error reporting E ALL    To fix your specific problem  don t do any calculations if there s no input from your form  just show the form instead

[php] PHP Warning: Division by zero

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