I am trying to compare the following: if the value is not an array or the value does not equal false, return.
if (is_array($value) != true || $value != false) return;
This, and any other variation I am trying doesnt seem to work. However, when I compare these individually in their own if statements they return the correct results.
Any help would be greatly appreciated!
You originally said "if it's not an array or not false". You're thinking backwards. You want "if the value is an array or false continue, else return".
So:
// This says: "if it's not (an array or false)"
if(!(is_array($value) || $value === FALSE)) return;
Using De Morgan's laws, we can convert this to
// This says: "if it's not an array and not false"
if(!is_array($value) && $value !== FALSE) return;
I would write it like this:
if (!is_array($value) || $value !== false)
Many things in php can be == false, but only boolean false can be === false.
Check out boolean type manual page and comparison operators manual page
Related
I am new to PHP and am currently constructing a do/while loop from a tutorial. I would understand if the whole condition was ($variable == true) or ($variable == false), however in the tutorial the while condition is simply while($variable). Could anyone explain this to me?
Here is the tutorial code.
<?php
$loopCond = false;
do {
echo "<p>The loop ran even though the loop condition is false.</p>";
} while ($loopCond);
echo "<p>Now the loop is done running.</p>";
?>
All such conditional statements, including while and if, are evaluating the given expression against true. If the expression results in true, the statement executes the action. If it results in false, it won't.
$var == true is an expression which compares $var to true. The result of this expression is either true or false. The important point to understand here is expressions. Expressions are things which return values. Try var_dump($var == true) or var_dump(4 > 6). It shows you that the expressions return a boolean value. Here:
if ($var == true)
first $var is compared to true, which yields either the value true or false, which is then evaluated by if whether it's true or false, which then prompts if to execute the following statement or not.
In other words: it's redundant.
if ($var)
This simply causes if to evaluate whether $var is true or false and then execute the following statement. The == true is essentially already "built in".
The following statements are all essentially equivalent:
if ($var)
if ($var == true)
if (($var == true) == true)
if ((($var == true)) == true) == true)
...
A boolean value true or false should not be used with a redundant $c == true as the result is the same as $c: true or false
$driving = true;
while ($driving) {
while ($driving == true) { // ugly
while (! $driving) { // while not driving.
while ($driving == false) { // ugly
$drinking = ! $driving;
if ($driving && $drinking) {
Hence also use adjectives for boolean variables.
A condition is met, if the value or statement in it is considered as true.
The code $variable == true is a statement that looks whether the value of the variable is true and if it is, yields true - Or false if it is not.
However, as this means, that $variable itself can only ultimately be true or false, you don't even need the statement, as its return value will also be one of those two.
Therefore $variable is exactly the same as $variable == true.
I hope this made it clear.
The semantic of while/do-while is
while(<boolean expression>) {
// do your stuff
}
A boolean expression is anything that evaluates to true or false. So, if $loopCount is true, then $loopCount == true is checked on every loop and evalutes to true. But you could also write $LoopCount as condition, since it also evaluates to true.
This is very handy for using other data types, e.g. integers.
$count = 0;
while ($count < 10) {
$count = $count +1;
}
Here $count < 10 is a boolean expression that evaluates to true as long as $count is not higher then 9.
A while loop runs as long as the condition is met, in other words, as long as the boolean expression you provide evaluates to true.
You can also just use a variable, e.g. $loopCount when that variable evaluates to a boolean or a constant (even the constant value true).
Like Padarom said: Therefore $variable is exactly the same as $variable == true.
In your case: The while-do loop determines if redo the loop-body after the first run. Means the loop-body is executed exactly one time regardless what value $variable has. After the first run, the while($variable) checks if the expression is true. If so, the loop-body is executed second time and so forth.
Check PHP reference for do-while loops here. PHP.net do-while reference
while ($loopCond) and while ($loopCond == true) is the same thing. It checks the "trueness" of whatever you put in the brackets.
If I ask a question "does sun set in the west ? " what would be your answer, definitely YES OR TRUE. Same as compiler always look for statement value. Take a look
$condition = true;
if($condition == true )
// above will return TRUE; in short $condition == true will replaced by true at runtime. But if we place true directly which is $condition value or can say we place $condition instead true thus statement become shorten and look like...
if($condition) {
}
Sorry for bad english , used Google.translate
There is a code that returns a value to a int, if set . Otherwise it returns false
if (isset($this->variable))
return intval ($this->variable);
else
return false;
On the receiving side condition
if ($return_value) {
// Here code
}
The problem is that if the returned value is 0, this is false, and the code is executed . But as the value of 0 is also important to me . If returned as a string , it is still treated as false.
define ('false', 'value') does not work.
Introduced his constant for this , but you have to rewrite a bunch of code for additional testing
(if($return_value! == my_false_constant)
That is not quite satisfied.
What options are there to solve this problem ?
if ($return_value !== false) {
}
Using !== (or ===) instead of just != or == also tests the type of the value.
Use strict comparison with ===.
See: http://us3.php.net/manual/en/types.comparisons.php
if(1 === true) //returns FALSE
This will work:
(if($return_value !== false){
// do work
}
Comparisons:
== means same value
=== means same value AND same type
! == means not (same value)
!== means not (same value and same type)
SO:
0 == false //is true
0 === false //is false
Simply ! == does not equal !==, as is not valid PHP code
I'm trying to test if either of two variables are true using the code below, but I the code always returns the true conditions even when the variable is blank. Have I done this correctly or is it possible the variables are always true?
Thanks in advance for your help.
<?php
if (($gogo_team_member_twitter !== true) or ($gogo_team_member_facebook !== true)) {
echo('class="amb-with-socal"');
}
else echo('class="amb-without-socal"');
?>
If you need "Testing if either of two condtions are true" then your condition should look like:
if ($gogo_team_member_twitter === true || $gogo_team_member_facebook === true)
or just
if ($gogo_team_member_twitter || $gogo_team_member_facebook)
if you don't need strict comparison
You have the right idea, but you're checking that the variables are not true. Surely you want to check if either is true?
Also, try to use || and && rather than or and and, as they have a higher precedence.
I would just write
if ($gogo_team_member_twitter || $gogo_team_member_facebook)
In addition when dealing with negatives like this you can use "and"
if ($gogo_team_member_twitter !== true && $gogo_team_member_facebook !== true)
Well, you are checking if any of the 2 variables is not exactly equal to true.
If the variable is blank, it is not true, and so the condition is met.
In PHP, how would one check to see if a specified item (by name, I think - number would probably also work) in an array is empty?
Types of empty (from PHP Manual). The following are considered empty for any variable:
"" (an empty string)
0 (0 as an integer)
"0" (0 as a string)
NULL
FALSE
array() (an empty array)
var $var; (a variable declared, but without a value in a class)
So take the example below:
$arr = array(
'ele1' => 'test',
'ele2' => false
);
1) $arr['ele3'] is not set. So:
isset($arr['ele3']) === false && empty($arr['ele3']) === true
it is not set and empty. empty() checks for whether the variable is set and empty or not.
2) $arr['ele2'] is set, but empty. So:
isset($arr['ele2']) === true && empty($arr['ele2']) === true
1) $arr['ele1'] is set and not empty:
isset($arr['ele1']) === true && empty($arr['ele1']) === false
if you wish to check whether is it empty, simply use the empty() function.
if(empty($array['item']))
or
if(!isset($array['item']))
or
if(!array_key_exists('item', $array))
depending on what precisely you mean by "empty". See the docs for empty(), isset() and array_key_exists() as to what exactly they mean.
<?php
$myarray=array(1,5,6,5);
$anotherarray=array();
function checkEmpty($array){
return (count($array)>0)?1:0;
}
echo checkEmpty($myarray);
echo checkEmpty($anotherarray);
?>
(for checking if empty result 1 else 0);
Compactness is what I persue in my code.
i had such situation where i was getting tab it last index of array so if put things together then this might work for the most of cases
<?php
if( ctype_space($array['index']) && empty($array['index']) && !isset($array['index']) ){
echo 'array index is empty';
}else{
echo 'Not empty';
}
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Fixing the PHP empty function
In PHP, empty() is a great shortcut because it allows you to check whether a variable is defined AND not empty at the same time.
What would you use when you don't want "0" (as a string) to be considered empty, but you still want false, null, 0 and "" treated as empty?
That is, I'm just wondering if you have your own shortcut for this:
if (isset($myvariable) && $myvariable != "") ;// do something
if (isset($othervar ) && $othervar != "") ;// do something
if (isset($anothervar) && $anothervar != "") ;// do something
// and so on, and so on
I don't think I can define a helper function for this, since the variable could be undefined (and therefore couldn't be passed as parameter).
This should do what you want:
function notempty($var) {
return ($var==="0"||$var);
}
Edit: I guess tables only work in the preview, not in actual answer submissions. So please refer to the PHP type comparison tables for more info.
notempty("") : false
notempty(null) : false
notempty(undefined): false
notempty(array()) : false
notempty(false) : false
notempty(true) : true
notempty(1) : true
notempty(0) : false
notempty(-1) : true
notempty("1") : true
notempty("0") : true
notempty("php") : true
Basically, notempty() is the same as !empty() for all values except for "0", for which it returns true.
Edit: If you are using error_reporting(E_ALL), you will not be able to pass an undefined variable to custom functions by value. And as mercator points out, you should always use E_ALL to conform to best practices. This link (comment #11) he provides discusses why you shouldn't use any form of error suppression for performance and maintainability/debugging reasons.
See orlandu63's answer for how to have arguments passed to a custom function by reference.
function isempty(&$var) {
return empty($var) || $var === '0';
}
The key is the & operator, which passes the variable by reference, creating it if it doesn't exist.
if(isset($var) && ($var === '0' || !empty($var)))
{
}
if ((isset($var) && $var === "0") || !empty($var))
{
}
This way you will enter the if-construct if the variable is set AND is "0", OR the variable is set AND not = null ("0",null,false)
The answer to this is that it isn't possible to shorten what I already have.
Suppressing notices or warnings is not something I want to have to do, so I will always need to check if empty() or isset() before checking the value, and you can't check if something is empty() or isset() within a function.
function Void($var)
{
if (empty($var) === true)
{
if (($var === 0) || ($var === '0'))
{
return false;
}
return true;
}
return false;
}
If ($var != null)