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.
Related
I found an example php assignment statement online which maybe resembles a tertary conditional condensed statement, but not quite. Does anyone have insight as to how to read this assignment statement?
$access = $access || $note->uid == $user->uid && user_access('note resource view own notes');
My first guess was "assign to access whatever is in access, or if empty, whether uid values are equal and'd with the return of user_access." But I get the feeling that is not correct, as it seems illogical.
First have a look at the Operator Precedence
== comes before && comes before || comes before =
Thus your statement is more clear with adding the following parentheses:
$access = (
$access
||
(
($note->uid == $user->uid)
&&
user_access('note')
)
);
assign to access whatever is in access, or if empty,
Not quite: assign to $access the value true* when $access already evaluates to true (true, 1, "some string" etc), or
whether uid values are equal and'd with the return of user_access
Correct
And otherwise assign false. After this statement $access is always either true or false, even when $access === 'yes' before.
Note*: || and && are boolean operators, only capable of 'returning' true or false
I had this exact type of statement in a library way back, and it's basically an elaborate (or maybe just badly-styled?) null-check. Because PHP uses short circuit evaluation, the right-hand side of the or-expression will not evaluate if the left hand one was null.
So I understand this - and comparing/checking values. However, I was messing about and noticed the outcome for all my tests were the same - some of which I was taught (a) didn't work or (b) was incorrect.
Note, I'm running PHP7. Okay, to my point. I was able to achieve the same outcome checking if a single value equals one of multiple options...
These work...why? Def not the way I learned.
if ($status == 'in-progress' || 'in-review')
// and even
if ($status == ('in-progress' || 'in-review')) // kind of similar to ASP.NET Razor
I normally would repeat the check, like so: if($stat == 'a' || $stat == 'b') or even in_array() which is essentially the same thing.
Is the first examples, correct? If not, why is it working? Or is this something frowned upon and not practiced - or maybe even something new?
First off to make it clear == has a higher precedence than ||. This means your two if statements look like this:
if (($status == 'in-progress') || 'in-review')
if ($status == ('in-progress' || 'in-review'))
Now for your first if statement regardless what value $status has and what the outcome of ($status == 'in-progress') is, since you have an OR in it and after it 'in-review' your if statement will always be true, since a non empty string is a truthy value.
For your second statement, this part ('in-progress' || 'in-review') comes literally down to TRUE || TRUE, which evaluates to TRUE. Now $status just needs to hold a truthy value and the if statement will be true.
No, that code will never work. || has a lower precedence than ==, so you're comparing $status against the first value, then boolean || "or" the other value
if (($status == 'foo') || ('bar'))
You have to compare the values individually:
if (($status == 'foo') || ($status == 'bar'))
And this gets tedious for many values. A quick hack is to use an array:
if (in_array($status, array('foo', 'bar', 'baz', 'qux', 'etc...')))
I am new to PHP and am currently constructing a do/while loop from a tutorial. I would understand if the whole condition was ($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) {
}
I am using CodeIgniter.
I set $config['global_xss_filtering'] = FALSE in a config file.
Then I find this code in system/core/Input.php:
$this->_enable_xss= (config_item('global_xss_filtering') === TRUE);
What actually this code it doing? It doesn't look like a ternary statement. It seems to me is
$this->_enable_xss= (FALSE === TRUE);
In this case $this->_enable_xss returns FALSE?
This expands out to:
// If global_xss_filtering is a boolean TRUE (by strict comparison)
if (config_item('global_xss_filtering') === TRUE) {
// Set _enable_xss to TRUE
$this->_enable_xss = TRUE;
}
// Otherwise set it FALSE
else $this->_enable_xss = FALSE;
The part in () (config_item('global_xss_filtering') === TRUE) is a boolean comparison which will return TRUE or FALSE. That value is stored in $this->_enable_xss.
So in your case, you are correct that you're evaluating
$this->_enable_xss= (FALSE === TRUE);
... which sets $this->_enable_xss to FALSE.
each comparison operator returns a boolean.
Yours checks if you got true left and right.
So, yes, var_dump(true === false);//bool(false)
is there more code around the statement? I would say your assessment is valid. Looking at this forum http://codeigniter.com/forums/viewthread/160281/#771216 it looks like it's just setting the _enable_xss based on the config value so you can control the setting. Why they need to do a comparison is beyond me, seems unnecessary.
I have an if statement that I want to control with having one field needing input and they have to pick one of the other 2 choices.
if(test1 && test || test3){
//Something here
}
Should I do it like this:
if(test1 && (test2 || test3)){
//do stuff
}
How would I go about doing this. I can't wrap my head around the logic...
if ($requiredField && ($optional1 || $optional2)) {
/* Do something */
}
For the /* Do something */ bit of code to be executed, the if statement has to evaluate to TRUE.
This means, that $requiredField must be TRUE, and so must be ($optional1 || $optional2).
For $requiredField to be TRUE, it just needs to be filled in - and for the second part: ($optional1 || $optional2) either optional1 or optional2 would do it.
Edit:
After rereading the question, it seems that I might have misunderstood you. If the user must enter one specific piece of information, and must choose only one (not both) out of two options - then the following should be used.
if ($requiredField && ($optional1 ^ $optional2)) {
/* Do something */
}
This means that $optional1 or $optional2 must be filled out - but not both of them.
From the sound of it, you want the latter:
if ($test1 && ($test2 || $test3)){
//do stuff
}
Think of it as two conditions needing to be met. This gives you those two conditions. The second condition just happens to be another condition. The first option you posted, however, is quite the opposite as it can allow execution if just $test3 is true
test1 && (test2 || test3) is very easy to understand from the first place - Choose test1 && (test2 || test3) means one the last two. Very clear.
test1 && test || test3 - doesn't seem to be correct:
test1 = false
test2 = false
test3 = true
false && false || true = true
doesn't actually fit your criteria.
... they have to pick one of the other 2 choices
I'm just throwing a guess out here. If you really want to ensure that one, but only one of the two other options are selected, then you need xor:
if ($required AND ($and_either XOR $or_other)) {
You can have 'nested' if statements withing a single if statement, with additional parenthesis.
if(test1 && (test2 || test3)){
//do stuff
}
Your logic is right but your sintax isnt, you should compare the values of the variables as show, or simply ignore them as saying you are trying to compare them as they are TRUE.
$test1=true;
$test2=true;
$test3=false;
if($test1==true && ($test2==true || $test3==true){ echo "YES";}
This will output YES.