"or die" construct question

[Anon]

Hello,
could someone help me understand this "or die.." construct?

I find this construct used for error handling, in combination with the @ prefix to suppress php error output. For example:

@($sql_query) or die("an error occurred..").

Now, I don't understand the semantic of this construct. I know OR as a boolean operator, taking two boolean arguments and returning a boolean result.

But here OR seems to be a control structure, used to execute the second function if the first one returns false.

Since OR is not among the control structures mentioned in the PHP Manual, I am not sure if I understand this right.

That would mean the php engine has to analize the context to figure out if in a given construct OR is the logical operator or the control structure.

Hey, that would be a really messy syntax grrrrrr .... ok, I'm new to PHP and already complaining ;-)

[Anon]

OR is always a logical operator, not a control structure. When PHP evaluates an expression such as this :

exp1 OR exp2

it first evaluates the first one. If it's true, it doesn't evaluate the second because it already knows the final result. If it's false, it does evaluate it.

The example you gave works like this (a function call is an expression) and the behaviour is exactly what we want : if connected, continue; if not, die.