IF statement not working

[Dummy99]

My code:

if($sw=='B')
            {print("sw=$sw<br>");
                print("<font color=maroon>Buy $amt <font color=red>$sw<br>");}

Results:

sw=0

Buy $0 0

Neither of these result lines should print.

Searched and searched and tested and tested but can't see any error in code.

Thanks for you help.

 

[Barand]

It works as expected when I run the code

[mac_gyver]

Quote

 

Warning

Prior to PHP 8.0.0, if a string is compared to a number or a numeric string then the string was converted to a number before performing the comparison.

 

as of php8 -

Quote

Non-strict comparisons between numbers and non-numeric strings now work by casting the number to string and comparing the strings.

either update to php8+ or use a strict comparison ===

[kicken]

You're probably running a version of PHP before 8.0 and suffering from it's poor handling of comparing integers and strings.  This was changed in PHP 8.0 to something that makes more sense.

Compare the output if you run the code on various versions of PHP: https://3v4l.org/vLB4b

The simple fix is to perform a strict comparison using the === operator instead.

if($sw === 'B'){
   print("sw=$sw<br>");
   print("<font color=maroon>Buy $amt <font color=red>$sw<br>");
} 

 

[ginerjm]

Since you are not happy how about telling us what you have set the value of $sw to?

[Dummy99]

That's what is expected but it doesn't work on my laptop nor on my phone - screen shot below.

Any idea why? I doubt it but could it be my web service provider?

[Dummy99]

Many thanks to all and in particular to Mac_Gyver who hit it right on. I change my == to === and everything works fine.

But I must say it is very peculiar because all of my if's wit == were working fine except this particular one and I'm pretty sure I had similar situations.

For the one giving trouble, I had set the $sw='' (which I thought was a blank or nothing) but when I printed it, it was a numeric 0 (which obviously gave me the trouble when I was checking for a 'B").  However, I had at least one other situation where I set $WL='' and when testing for a W, if($WL=='W') ,I was getting correct results (or so it seems - maybe the results were incorrect and I didn't notice it - that's the only explanation I have.)

Again, many thanks.

[Dummy99]

Sorry.

Special thanks to kicken who said to use  ===  instead of ==, are also in order.

[kicken]

37 minutes ago, Dummy99 said:

However, I had at least one other situation where I set $WL='' and when testing for a W, if($WL=='W') ,I was getting correct results

The empty string ('') will compare correctly using ==, because it's a string.  This issue is specifically when you are testing a numeric value against a string.  Somewhere in your code $sw is getting set to the numeric value 0 and not the empty string as you thought and that's what lead to the problem.

In general, using strict comparison is a good habit to develop to save help ensure you're dealing with the correct types.

 

[Dummy99]

You are absolutely correct. In my initialization of $sw in a start-up file, I was inadvertently setting $sw=0 and of the many times I checked, I missed it. As you said, with $sw='' it would have worked. I thought I had initialized with $sw='' and I therefore couldn't understand why it was not working. After you last statement, I checked again and corrected it.

Thank you so much.