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I was looking at some PHP code:
<?php
-$username = "admin";
-$password = "secret";
-$database = "mystore";
mysql_connect("localhost", $username, $password);
mysql_select_db($database);
What is the function of the minus-sign in front of the variable names?
If I do the same in the PHP interpreter, it results in valid code and there seems to be no difference:
$ php -a
Interactive shell
php > $a=1;echo $a;
1
php > -$a=2;echo $a;
2
I asked Google but she couldn't help me.
439
PHP abs() Function echo(abs(6.7) . "<br>"); echo(abs(-6.7) . "<br>");
To assign by reference, simply prepend an ampersand (&) to the beginning of the variable which is being assigned (the source variable).
Hello @kartik, The @ symbol is the error control operator ("silence" or "shut-up" operator). It makes PHP suppress any error messages (notice, warning, fatal, etc) generated by the associated expression. It works just like a unary operator, for example, it has a precedence and associativity.
A variable variable takes the value of a variable and treats that as the name of a variable. In the above example, hello, can be used as the name of a variable by using two dollar signs. i.e. $$a = 'world'; ?>
-$username = "admin"; is evaluated as - ($username = "admin");
That is, a prefix unary operator - applied to the expression.
The expression consists of an assignment only.
So a string is assigned to a variable, then as per php syntax the expression returns the same value which is implicitly converted to a number and negated. Then the result is thrown away.
So there is no special meaning here, someone put it there accidentally.
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