number as variable name not possible right? But this works
${4} = 444;
echo ${4};
Question: How much is this justified using this syntax? and where is info about this in documentation? I not found.
The syntax is covered in Variable variables. No, you are not "justified" in using this syntax. You should absolutely never do this, there is no good reason for using a number as a variable name.
Variables between brackets are considered valid (variable variables), no matter the syntax.
${'sad asda sda'} = 444;
echo ${'sad asda sda'};
// still works.
this is also works
$_4 = 444;
echo $_4; //output 444.
This is a perfectly ok json string:
$json_str = '{"1": "One", "02": "Two"}';
So if I were to decode it:
$json_object = json_decode($json_str);
the way to access the elements is:
$one = $json_object->{1};
$two = $json_object->{"02"};
Related
With code something like this
$tk = intval($_GET['tk']);
$vosa = $_GET['vosa'];
echo $tk*100*$vosa;
Where $vosa is a string of something like 0.0425/1920*60*8. I'd need it replaced, without being calculated first, into the echo and then echo the entire thing $tk*100*0.0425/1920*60*8 result. How could I achieve this?
Ok another version. Replace the values in your string with sprintf.
echo sprintf("%s*100*%s", (string)$tk, (string)$vosa);
if %d for digit don't match your case then you can use %s. You use in your case directly $_GET variables. So sprintf is a good choice. I have tested it with:
php -r 'echo sprintf("%s*100*%s", "123", "4.000");'
output:
123*100*4.000
To output, just echo the string:
echo "{$vosa} = {$result}";
Your problem is how to calculate $result from $vosa.
A very risky way would be to use eval() - or as someone sometimes calls it, evil().
The risk is that I could send you a vosa value of system('FORMAT C: /AUTOTEST') (which would not work, but you get my meaning).
// vosa='/bin/dd if=/dev/zero of=etc etc'
// This will return zero. It will return a whole lot of zeroes
// all over your hard disk.
$result = eval("return {$tk}*100*{$vosa};");
Possibly, validating $vosa with a regular expression could help, at least as long as you use simple expressions.
Alternately, you must implement an expression parser.
This is another ready made. You would use it like this:
include('./some/where/mathparser.php');
$parser = new MathParser();
$parser->setExpression("{$tk}*100*{$vosa}");
$result = $parser->getValue();
echo "The result of {$tk}*100*{$vosa} is {$result}.";
You can use string and then use eval to execute it as a php code:
<?php
$tk = intval($_GET['tk']);
$vosa = $_GET['vosa'];
echo eval("return $tk*100*$vosa;");
Caution
The eval() language construct is very dangerous because it allows execution of arbitrary PHP code. Its use thus is discouraged. If you have carefully verified that there is no other option than to use this construct, pay special attention not to pass any user provided data into it without properly validating it beforehand.
$tk = intval($_GET['tk']);
$vosa = $_GET['vosa']; // "0.0425/1920*60*8"
$ans = eval('return '.$vosa.';');
echo $ans;
echo "<br>";
echo $tk*100*$ans;
Example : https://eval.in/819834
Got it myself
<?php
$tk = $_GET['tk'];
$aeg = $_GET['aeg'];
$kfc = $_GET['kfc'];
$vosa = $_GET['vosa'];
$final = $tk.'*'.$aeg.'*'.$kfc.'*'.$vosa;
$ans = eval('return '.$final.';');
echo round($ans,2);
I have a string (a c code) in a vairable. I want to print it php. But i don't why everything after double quotes in not printing.. pls help. Below is the code.
$answer_something='printf("\\n")';
echo $answer_something;
//OUTPUT: printf(
//WHAT I WANT TO PRINT IS printf("\\n");
The PHP syntax for strings is explained in the Strings chapter of the manual. To produce static strings with code samples into variables I'd go for nowdoc:
<?php
$str = <<<'EOD'
printf("\\n");
You can write almost anything you want. No 'escaping' "needed" \r \n \
EOD;
var_dump($str);
Of course, this does not apply if you read information from the $_POST superglobal array: the array will automatically contain whatever the user submitted.
How about using:
$x = 'printf("\\\\n");';
echo $x;
I suppose this is for some kind of trivia / questionnaire. You have to escape each backslash with 2 backslashes.
You can check the output here: http://ideone.com/fFvb28
try this:
$answer_something = $_POST['option'];
if($answer_something == '\\n'){
printf("\\n");
}
I'm storing some strings within a *.properties file. An example of a string is:
sendingFrom=Sending emails from {$oEmails->agentName}, to {$oEmails->customerCount} people.
My function takes the value from sendingFrom and then outputs that string on the page, however it doesn't automatically parse the {$oEmails->agentName} within. Is there a way, without manually parsing that, for me to get PHP to convert the variable from a string, into what it should be?
If you can modify your *.properties, here is a simple solution:
# in file.properties
sendingFrom = Sending emails from %s, to %s people.
And then replacing %s with the correct values, using sprintf:
// Get the sendingFrom value from file.properties to $sending_from, and:
$full_string = sprintf($sending_from, $oEmails->agentName, $oEmails->customerCount);
It allows you to separate the logic of your app (the variables, and how you get them) from your presentation (the actual string scheme, stored in file.properties).
Just an alternative.
$oEmails = new Emails('Me',4);
$str = 'sendingFrom=Sending emails from {$oEmails->agentName}, to {$oEmails->customerCount} people.';
// --------------
$arr = preg_split('~(\{.+?\})~',$str,-1,PREG_SPLIT_DELIM_CAPTURE);
for ($i = 1; $i < count($arr); $i+=2) {
$arr[$i] = eval('return '.substr($arr[$i],1,-1).';');
}
$str = implode('',$arr);
echo $str;
// sendingFrom=Sending emails from Me, to 4 people.
as others mentioned eval wouldn't be appropriate, I suggest a preg_replace or a preg_replace_callback if you need more flexibility.
preg_replace_callback('/\$(.+)/', function($m) {
// initialise the data variable from your object
return $data[$m[1]];
}, $subject);
Check this link out as well, it suggests the use of strstr How replace variable in string with value in php?
You can use Eval with all the usual security caviats
Something like.
$string = getStringFromFile('sendingFrom');
$FilledIn = eval($string);
I would like to know when and why should I use {$var}
echo "This is a test using {$var}";
and when (and why) should I use the simple form $var
echo "This is a test using $var";
You would use the latter when a) not accessing an object or array for the value, and b) no characters follow the variable name that could possibly be interpreted as part of it.
http://php.net/manual/en/language.variables.variable.php
In order to use variable variables with arrays, you have to resolve an
ambiguity problem. That is, if you
write $$a[1] then the parser needs to
know if you meant to use $a[1] as a
variable, or if you wanted $$a as the
variable and then the [1] index from
that variable. The syntax for
resolving this ambiguity is: ${$a[1]}
for the first case and ${$a}[1] for
the second.
The brackets allow you to remove ambiguity for the PHP parser in some special cases.
In your case, they are equivalent.
But consider this one:
$foobar = 'hello';
$foo = 'foo';
echo "${$foo . 'bar'}"; // hello
Without the brackets, you will not get the expected result:
echo "$$foo . 'bar'"; // $foo . 'bar'
For clarity purposes, I would however strongly advise against this syntax.
If you write
echo "This is a test using $vars"
You do not get content of $var in result text.
If you write
echo "This is a test using {$var}s";
Everything will be OK.
P.S. It works only with "" but not for ''.
The {} notation is also useful for embedding multi-dimensional arrays in strings.
e.g.
$array[1][2] = "square";
$text = "This $array[1][2] has two dimensions";
will be parsed as
$text = "This " . $array[1] . "[2] has two dimensions";
and you'll end up with the text
This Array[2] has two dimensions
But if you do
$text = "This {$array[1][2]} has two dimensions";
you end up with the expected
This square has two dimensions.
OK, so there is a page I'm querying on another server that returns a comma separated list of two values. Something it would return would be:
850,640
I have some PHP code that calls file_get_contents on that page and needs to do some numeric calculations based on the two values.
No matter what I try, I can't seem to get an int value out of this.
$res = trim(file_get_contents('http://thatURL/'));
echo "X" . $res . "X<br/>";
list($x,$y) = array_map(create_function('$a', 'return (int)$a;'), explode(',', $res));
echo "X:$x";
results in the output:
X 850,640 X
X:0
Note the spaces before and after the comma separated values(how the hell? I trim'd them!) and that $x is assigned the value 0.
What am I doing wrong here?
What am I doing wrong here?
Nothing, as far as I can see, which indicates that the content of $res is not quite what you expect. Could you change the first echo to:
echo htmlentities($res);
My guess is $res contains some un-printed characters, for example, it is actually:
<span> </span>850,640<span> </span>
or
850,640
Try the following. The array_map and llamda function are arguably overkill for your usage.
$res = " 850,640 ";
echo "X" . $res . "X<br/>";
list($x,$y) = explode(',', trim($res));
echo "X:" . (int)$x;
echo "Y:" . (int)$y;
Worked for me, but I'm not using file_get_contents(). If that doesn't work, something else is being output by the page.
PHP is not a typed language. Use intval to convert a string to integer.
Correction: it is a loosely typed language! That's what I meant!
Since I was using file_get_contents() on a URL, there was some HTML being put in as well that I didn't notice in my echo because it parsed out... just empty body and html tags. Oops!