An IF statement cannot be found for one day.

An IF statement cannot be found for one day. The code is as follows:

If ($ webstate! = "Y" or $ webstate! = "N") {echo "script" alert ('prompt: illegal error! Error Code: State! '); History. back (-1); script "; exit ;}

My idea is: $ is only in two cases: Y and N. If the third case occurs, an error is returned.

Now, if I only need one condition, it will be normal. if I add one OR more conditions, it will be abnormal (an error will be reported whether it is equal to Y OR N .)

Reply to discussion (solution)

My idea is: $ is only in two cases: Y and N. If the third case occurs, an error is returned.

According to your statement, the third case is that it is not Y and not N. It should be "and", not "or ".

Incorrect logical relationship with and

If ($ webstate! = "Y" | $ webstate! = "N "){
//
} Else {
//
}

If ($ webstate! = "Y" and $ webstate! = "N ")
Or
If (! ($ Webstate = "Y" or $ webstate = "N "))

My idea is: $ is only in two cases: Y and N. If the third case occurs, an error is returned.

According to your statement, the third case is that it is not Y and not N. It should be "and", not "or ".

I walked into a dead end by myself. thank you.