if(0 == ('Pictures'))
{
echo 'true';
}
why it's giving me 'true' ?
Your string will be evaluated as an Integer, so becomes 0, use this : 0 === 'Pictures' that verifies identity (same value and same type)
Check PHP type comparison tables to understand how comparison operators behave in PHP.
In your case, 'Pictures' becomes "0" and therefore 0 = 0.
Let's check following example:
echo (int)'Pictures'; // 0 => 'Picture' as int
echo 0 == 'Pictures'; // 1 => true, 0 = 0
Use:
if (0 === 'Pictures')
{
echo 'true';
}
The === is strict type operator, it not only checks the value but the type as well.
Quick Test:
if(0 == 'Pictures')
{
echo 'true';
}
else
{
echo 'false';
}
outputs true but:
if(0 === 'Pictures')
{
echo 'true';
}
else
{
echo 'false';
}
outputs false
Related
Here is my sample code:
$issue_id = $_POST['issue_id'];
if(!empty($issue_id)){
echo 'true';
}
else{
echo 'false';
}
If I pass 0 to $_POST['issue_id'] by form submitting then it echo false. Which I want is: Condition will be true if the following conditions are fulfilled:
1. true when I pass any value having 0.
2. false when I don't pass any value. i.e: $_POST['issue_id'] is undefined.
I also tried this:
if(!isset($issue_id)){
echo 'true';
}
else{
echo 'false';
}
if(!empty($issue_id) || $issue==0){
echo 'true';
}
else{
echo 'false';
}
The last one is okay, meaning if I pass any value having ZERO then it will echo true. But it will also echo true if I don't pass any value. Any idea?
The last is okay, meaning if I pass any value having ZERO then it echo true. But it also echo true if I don't pass any value. Any idea?
if (isset($_POST["issue_id"]) && $_POST["issue_id"] !== "") {
}
please notice I used !== not !=. this is why:
0 == "" // true
0 === "" // false
See more at http://php.net/manual/en/language.operators.comparison.php
also if you are expecting number you can use
if (isset($_POST["issue_id"]) && is_numeric($_POST["issue_id"])) {
}
since is_numeric("") returns false
http://php.net/manual/en/function.is-numeric.php
Alternatively if you expect number good option is filter_var
if (isset($_POST["issue_id"]) {
$issue_id = filter_var($_POST["issue_id"], FILTER_VALIDATE_INT);
if ($issue_id !== false) {
}
}
since filter_var("", FILTER_VALIDATE_INT) will returns false and filter_var("0", FILTER_VALIDATE_INT) will return (int) 0
http://php.net/manual/en/function.filter-var.php
if(isset($_POST['issue_id'])) {
if($_POST['issue_id'] == 0) {
echo "true";
}
else {
echo "false";
}
}
When you get data from a form, remember:
All text boxes, whether input or textarea will come as strings. That includes empty text boxes, and text boxes which contain numbers.
All selected buttons will have a value, but buttons which are not selected will not be present at all. This includes radio buttons, check boxes and actual buttons.
This means that $_POST['issue_id'] will be the string '0', which is actually truthy.
If you need it to be an integer, use something like: $issue_id=intval($_POST['issue_id']);
#Abdus Sattar Bhuiyan you can also full fill your two condition like below one:
<?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';
}
I have $first and $second. They can have value 0 or 1.
if ( $first AND $second ) {
// True
} else {
// False
}
My mind (and Google search) tells me, that the result is true only when $first == 1 and $second == 0 or vice versa. But the result is true when both of this variables are 1.
I don't understand how does it works.
Your Google searches have failed you. PHP's type juggling means that a 1 is equivalent to TRUE and 0 is equivalent to FALSE. (See also type comparisons). So if both values are 1 then that if statement evaluates to TRUE. If one or both values are 0, it evaluates to FALSE.
<?php
$one = 1;
$zero = 0;
if ($one && $one) {
echo "true\n";
}
else {
echo "false\n";
}
if ($zero && $zero) {
echo "true\n";
}
else {
echo "false\n";
}
if ($one && $zero) {
echo "true\n";
}
else {
echo "false\n";
}
if ($zero && $one) {
echo "true\n";
}
else {
echo "false\n";
}
Program Output
true
false
false
false
Demo
In PHP all values are either "truthy" or "falsy" in expressions.
If a value contains something then it can be said to be truthy. So, values such as 1, "one", [1,2,3] or true all "contain" something and will be interpreted as truthy.
Values that are zeroed or in some way empty are falsy. E.g. 0, "", [] and false.
There is a table of how values are interpreted in the PHP documentation.
You can also just experiment, and output it to your website:
var_dump(1 and 0);
i got into some trouble by using OR if one condition is true and the other false.
in my constillation right now it is always only the second condition token.
if($num_rows === '0' OR $_GET['id'] !== $_SESSION['UserID'])
{ echo "show me something"; }
else
{ show nothing; }
i get only always 'show nothing'.
Note that === is strict comparison. I think the following:
$num_rows === '0'
should rather be:
$num_rows == 0
$num_rows is presumably an integer and not a string (a piece of text).
Related: PHP == vs === on Stack Overflow
Watch out with the second comparison, too:
$_GET['id'] !== $_SESSION['UserID']
Here, it's probably better to use != in favor of !== as well. $_GET is generally read as string, so even something like ?id=5 will return as string "5" and not as integer 5
Here's a quick test to illustrate:
if (isset($_GET['id'])) {
echo '<h2>Comparison with == 5</h2>';
var_dump( ($_GET['id'] == 5) );
echo '<h2>Comparison with == "5"</h2>';
var_dump( ($_GET['id'] == "5") );
echo '<h2>Comparison with === 5</h2>';
var_dump( ($_GET['id'] === 5) );
echo '<h2>Comparison with === "5"</h2>';
var_dump( ($_GET['id'] === "5") );
}
else {
echo 'Please set an ?id to test';
}
This will output (notice the third item is false) the following with ?id=5:
Comparison with == 5
boolean true
Comparison with == "5"
boolean true
Comparison with === 5
boolean false
Comparison with === "5"
boolean true
Probably because you use absolute equality with a string.Mysli_num_rows returns an int.
http://php.net/manual/en/language.operators.comparison.php
Equal and of the same type
You dont need to use === as it is a strict comparison and $num_rows is probably an int Try this:-
if($num_rows == 0 OR $_GET['id'] != $_SESSION['UserID'])
$_GET['id'] will provide you a string. You may chech the manual for details
To be really correct, need something like this:
if ($num_rows === FALSE) {
echo 'db resource/link gone';
}
elseif ($num_rows === 0 || intval($_GET['id']) !== intval($_SESSION['UserID'])) {
echo 'no db result or id mismatch';
}
elseif (intval($num_rows) > 0 && intval($_GET['id']) === intval($_SESSION['UserID'])) {
echo 'everything good';
}
else {
echo 'something unhandled went wrong';
}
thanks for all the answers. i got it to work. i change the order and the opreator to what you've suggested.
i made it like this:
if($num_rows > 0 OR $_GET['id'] == $_SESSION['UserID']) { echo "show nothing"; }
else { show me some stuff }
so thanks again for all the help. :)
I have a variable that can be int or bool, this is because the db from where im querying it change the variable type at some point from bool to int, where now 1 is true and 0 is false.
Since php is "delicate" with the '===' i like to ask if this is the correct why to know if that var is true:
if($wallet->locked === 1 || $wallet->locked === true)
I think in this way im asking for: is the type is int and one? or is the var type bool and true?
How will you approach this problem?
Your code is the correct way.
It indeed checks if the type is integer and the value is 1, or the type is boolean and the value is true.
The expression ($x === 1 || $x === true) will be false in every other case.
If you know your variable is an integer or boolean already, and you're okay with all integers other than 0 evaluating to true, then you can just use:
if($wallet->locked) {
Which will be true whenever the above expression is, but also for values like -1, 2, 1000 or any other non-zero integer.
$wallet->locked = 1;
if($wallet->locked === true){
echo 'true';
}else{
echo 'false';
}
will produce:
false
and
$wallet->locked = 1;
if($wallet->locked == true){
echo 'true';
}else{
echo 'false';
}
will produce:
true
Let me know if that helps!
Your solution seems to be perfect, but You can also use gettype. After that You can check the return value with "integer" or "boolean". Depending on the result You can process the data the way You need it.
solution #1. If $wallet has the value of either false or 0, then PHP will not bother to check its type (because && operator is short-circuit in PHP):
$wallet = true;
//$wallet = 1;
if( $wallet && (gettype($wallet) == "integer" || gettype($wallet) == "boolean") )
{ echo "This value is either 'true and 1' OR it is '1 and an integer'"; }
else { echo "This value is not true"; }
solution #2 (depending on what You want to achieve):
$wallet = 0;
//$wallet = 1; // $wallet = 25;
//$wallet = true;
//$wallet = false;
if($wallet)
{ echo "This value is true"; }
else { echo "This value is not true"; }
This is the code
$a = 'Rs 15.25';
if ( $a != '' && $a! = 0 ) {
echo "Inside If";
} else {
echo "Outside If";
}
actually I want to Print "Inside If" so that's why I put $a='Some String Value'. But it always prints "Outside If". Then I changed my code to
$a = 'Rs 15.25';
if ( $a != '' && $a != '0' ) {
echo "Inside If";
} else {
echo "Outside If";
}
I have just added single quotes to 0. Then i got the exact output as i want. But I didn't understand why this happens.
So please help me with this.
PHP does weak type comparison, that is, it converts both operands to the same type before doing the actual comparison.
If one of the operands is a number, the other one is converted to a number as well. If the second operand is a string and contains no digits, it is silently converted to the number 0.
To avoid this whole issue, use string type checking with the operator !== (=== for equality).
if($a !== '' && $a !== 0) {
echo "Inside If";
} else {
echo "Outside If";
}
First of all you when you have multiple conditions on an if statement you should always enclose each of them within brackets
So first thing you should do is to change your code to
$a='Rs 15.25';
if(($a!='') && ($a!='0'))
{
echo "Inside If";
}else
{
echo "Outside If";
}
In PHP 0 = FALSE, 1 = TRUE.
if($a != 0) -> if($a != FALSE)
if $a = 'Rs 15.25', $a != false and $a not empty, then you have echo "Outside If";