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How to treat null values ​​as true using php?

Here's my sample code:

$issue_id = $_POST['issue_id'];
if(!empty($issue_id)){
  echo 'true';
}
else{
   echo 'false';
}

If I 0 to $_POST['issue_id']

submit over the submit form then it returns false. What I want: the condition will be true if the following conditions are true: 1. true when I pass any value that has 0. 2. false when I don't pass any value. ie: $_POST['issue_id']

undefined.

I also tried this:

if(!isset($issue_id)){
  echo 'true';
}
else{
   echo 'false';
}


if(!empty($issue_id) || $issue==0){
  echo 'true';
}
else{
   echo 'false';
}

The latter is fine, that is, if I pass in any value that has ZERO, then it will echo true. But it will also be true if I do not pass any value. Any ideas?

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4 answers


The latter is fine, that is, if I pass in any value that has ZERO then it will echo true. But this is also true if I don’t convey any value. Any idea?

if (isset($_POST["issue_id"]) && $_POST["issue_id"] !== "") {
}

Please note that I used !==

not !=

. that's why:

0 == "" // true
0 === "" // false

More details at http://php.net/manual/en/language.operators.comparison.php

also if you expect a number you can use

if (isset($_POST["issue_id"]) && is_numeric($_POST["issue_id"])) {
}


because it is_numeric("")

returns false

http://php.net/manual/en/function.is-numeric.php

Alternatively, if you expect parameter number to be good filter_var 

if (isset($_POST["issue_id"]) {
   $issue_id = filter_var($_POST["issue_id"], FILTER_VALIDATE_INT);
   if ($issue_id !== false) { 
   }
}

since it filter_var("", FILTER_VALIDATE_INT)

will return false and filter_var("0", FILTER_VALIDATE_INT)

return(int) 0

http://php.net/manual/en/function.filter-var.php

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When you receive data from a form, remember:

  • All text boxes, whether input

    or not textarea

    , will display as strings . This includes blank text boxes and text boxes containing numbers.
  • All selected buttons will have a value, but buttons that are not selected will not be present at all. This includes radio buttons, checkboxes, and actual buttons.


This means there $_POST['issue_id']

will be a string '0'

that is actually true.

If you need to get an integer, use something like: $issue_id=intval($_POST['issue_id'])

;

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if(isset($_POST['issue_id'])) {
  if($_POST['issue_id'] == 0) {
    echo "true";
  }
  else {
   echo "false";
  }
}
-1


source


@Abdus Sattar Bhuiyan you can also fill in all two conditions as below:

<?php
$_POST["issue_id"] = "0";
$issue_id = isset($_POST['issue_id']) ? (!empty($_POST['issue_id']) || $_POST['issue_id'] === 0 || $_POST['issue_id'] === "0")  ? true : false : false;
if($issue_id){
  echo 'true';
}
else{
   echo 'false';
}
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