IF语句中的PHP逻辑运算符

Question

I have the following code:

PHP

if($brand == 'ABC' && $main == ''){
    include '../_inc/report.php';
}else
if($brand == 'ABC' && $main == 'TRUE'){
    include '../_inc/analysis.php';
}else
if($brand == 'XYZ' || $brand == '123' || $brand == '1A9' && $main == ''){
    include '../_inc/report.php';
}else
if($brand == 'XYZ' || $brand == '123' || $brand == '1A9' && $main == 'TRUE'){
    include '../_inc/analysis.php';
}

Information is passed to the PHP page within the URL, such as:

?br=ABC&cr=MAY2014&pd=NOV2013&mn=TRUE
?br=XYZ&cr=MAY2014&pd=NOV2013&mn=TRUE

And handled as follows:

$brand = $_GET['br'];
$main = $_GET['mn'];

What is happening is that if $brand = ABC and $main = TRUE then the analysis.php is loaded successfully (which is correct).

However, if $brand = XYZ and $main = TRUE then report.php is loaded, which is not the behaviour I expect or need.

Is this connected with the way the operators work or is my code incorrect. Any help and feedback welcomed.

Answer 1

&& has higher precedence than ||. Your current code does this:

if($brand == 'XYZ' || $brand == '123' || ($brand == '1A9' && $main == '')){

This evaluates to true, because $brand == 'XYZ' is true. Use parentheses to correct the statement:

if(($brand == 'XYZ' || $brand == '123' || $brand == '1A9') && $main == ''){

See Operator Precedence for more details.