This question already has answers here:
What is the proper way to declare variables in php?
(5 answers)
Closed 9 months ago.
The first appearance to this variable $totpro in my code is this way
$totpro = $totpro + $row['profitloss'];
I want to use it to sum all profits, however, I receive this warning message on running
Warning: Undefined variable $totpro
but if I put this code before the previous code it runs with no problems
$totpro = "0";
I don't like using that code to declare the function, it tried
String $totpro
but unexpectedly it didn't work. Now tell me how to define $totpro without to have to use $totpro = "0";
If you are summing numbers, the initial declaration should set the value to 0 (i.e. a number):
$totpro = 0;
You tried "0", which is a string. Technically this will work, but it is not the best way.
Related
This question already has answers here:
Should an array be declared before using it? [closed]
(7 answers)
Closed 7 years ago.
In most languages, I have to initialize an associative array before I can use it:
data = {}
data["foo"] = "bar"
But in PHP I can just do
data["foo"] = "bar"
Are there any repercussions to doing this? Is this "the right way" to write PHP?
Is the same, but is not a good idea, the next is a copy-paste from php documentation.
If $arr doesn't exist yet, it will be created, so this is also an alternative way to create an array. This practice is however discouraged because if $arr already contains some value (e.g. string from request variable) then this value will stay in the place and [] may actually stand for string access operator. It is always better to initialize variable by a direct assignment.
Basically it's the same, and no you won't find any problem or repercussion.
But if you like you can do this:
$a = array();
You can read more in the PHP page
This question already has an answer here:
Notice: Unknown: Skipping numeric key 1 in Unknown on line 0
(1 answer)
Closed 7 years ago.
example:
$_SESSION['10'] = 'testing';
echo $_SESSION['10'];
The above will not print out anything...i found out(after a long time of frustration) that you cannot use a string numeral as a index for the $_SESSION variable. Anyone know why?
Quote from here:
The PHP session storage mechanism was originally built around
"registering" variables, so the keys in $_SESSION must be names that
could be treated as variables in their own right.
This means that $_SESSION[10] is invalid, because $10 wouldn't be
a valid variable name, and since $foo[10] and $foo['10'] refer to
the same thing, $_SESSION['10'] is invalid as well.
This question already has answers here:
Accessing an array element when returning from a function
(3 answers)
Closed 9 years ago.
Say I have a function/method that returns an array, let's call it ArrayReturner(). But I only want the first element, [0]. Right now I'm doing something like...
$arrayReturned = ArrayReturner();
$varIWant = $arrayReturned[0];
Is there a way to do that in one line without the need for the temporary $arrayReturned array?
Try:
$arrayReturned = reset(ArrayReturner());
Depends on PHP's version you use.
If you're using PHP < 5.4, then you cannot get that, like ArrayReturner()[0]. That's only possible in PHP >= 5.4.
If you want your code to be portable, that would work with old and new versions, then you'd better stick with that code:
$arrayReturned = ArrayReturner();
$varIWant = $arrayReturned[0];
This question already has answers here:
Check if url contains parameters [duplicate]
(3 answers)
How to verify if $_GET exists?
(7 answers)
Closed 9 years ago.
I have lots of PHP statements along the lines of:
$getvalue = $_GET['valueiwant'];
In some scenarios not all variables are available. So, let's say 'valueiwant' doesn't exist in the URL string, how can I return a value based on the fact it doesn't exist?
For example if 'valueiwant' can't be found set $getvalue to -1
Currently it appears the value defaults to 0 and I need to be equal less than 0 if it doesn't exist.
Any ideas?
thanks
I always use
$getvalue=isset($_GET['valueiwant'])?$_GET['valueiwant']:-1;
Use of the isset() function checks if the offset exists, and returns a boolean value indicating it's existence.
This means that you can structure an if statement around the output.
This question already has answers here:
Mixing a PHP variable with a string literal
(5 answers)
Closed 9 years ago.
I have a variable and I want to create a variable with that. I get the variable from database and put it together with some text and then I want another variable.
For exampel
$a = $ . "txt" . $d;
Try with this. It will create a variable from another one.
$a = ${'txt'.$d}
P.s. This is a question asked a couple of times. You might have found the answer simply by searching the issue on google.