有条件的条件......可能吗？

Question

Sorry, I am pretty new to php.

Is something like this possible?

if ( if ($clauseA) { A } if ($clauseB) { || B } ) {
    // Do Stuff
}

What I want to do is if $clauseA is true, include A in condition and if $clauseB is true, then include || B (OR and B) in condition.

Is there any solid way to achieve this?

Answer 1

Looks like you're trying to do this....

1. If Clause A is true, evaluate A as part of your condition, OR
2. If Clause B is true, evaluate B as part of your condition:

Code:

if (($clauseA && A) || ($clauseB && B)) {
    // Do Stuff
}

Answer 2

Logical or , aliased || , always works this way. If the first conditional expression does not evaluate to true, the second conditional expression is not tested or executed.

The same goes for and ( && ), it will not continue if the first expression evaluates to false.

Update: In fact, I think I just understood the question. :)

if ( ($clauseA && A) || ($clauseB && B) ) {
    // A and B will only be checked if the appropriate clause is true, otherwise they are ignored.
}

Answer 3

if ($clauseA) { if ($clauseB) { B } else { A } // Do stuff }

Answer 4

In boolean logic, this is expressed as:

if (($clauseA && $a) || ($clauseB && $b))

Or some variation thereof, depending on what exactly you want to do. The point being, you can express it using a combination of && and || , without if .

Answer 5

If A and B are boolean conditions that only have to be true if $clauseA or $clauseB are true as well, just rewrite your condition like this:

if( (!$ClauseA || $A) && (!$ClauseB || $B)) {
    // Do Stuff
}

I just applied De Morgan's laws ( http://en.wikipedia.org/wiki/De_Morgan 's_laws) to accomplish this.

Answer 6

Depending on the following: $clauseA might be true and/or $clauseB may be true, but both can be false:

if ((($clauseA || $clauseB) && A) || ($clauseB && B))
{ 
    // Doing some stuff     
}