Check if false using xor

[tommy20]

 

I want to check if a files is either jpeg or jpg and stop exit if it is something else. If tried this but it lets files that are not either jpeg or jpg load.

 

What can i do

 

if (!($uploaded_type=="image/jpg") xor !($uploaded_type=="image/jpeg" ) ) {

echo "You may only upload jpg picture files.<br>";

$ok=0;

exit();

}

 

 

[Zane]

xor means (either or).. not both.

just use or.

[tommy20]

That didn't work

[Zane]

try

if (($uploaded_type != "image/jpg") or ($uploaded_type != "image/jpeg"))

 

 

[Daniel0]

 

I want to check if a files is either jpeg or jpg and stop exit if it is something else. If tried this but it lets files that are not either jpeg or jpg load.

 

What can i do

 

if (!($uploaded_type=="image/jpg") xor !($uploaded_type=="image/jpeg" ) ) {

echo "You may only upload jpg picture files.<br>";

$ok=0;

exit();

}

 

When you're having trouble with propositional logic, it's often a good idea making a truth table

 

If we say that:

p: $uploaded_type=="image/jpg"

q: $uploaded_type=="image/jpeg"

 

Then the truth table looks like this:

 

[pre]p | q | ~p ⊕ ~q

---------------

T | T |    F

T | F |    T

F | T |    T

F | F |    F[/pre]

[tommy20]

This still isn't working

[PFMaBiSmAd]

And if you work out a truth table using OR you will find the it won't work either (because negative logic is being used in the tests, you would need to use AND.) Which is why it is usually best to test for allowed values and do something if a value is one of the possible allowed values.

[tommy20]

How can i do that

[Daniel0]

Replace or/xor with and...

[Mchl]

How about something easy to scale out?

 

$allowedTypes = array(
  "image/jpeg",
  "image/jpg",
);

if(!in_array($uploaded_type,$allowedTypes) {
  echo "You may only upload jpg picture files.<br>";
} 

 

 

[tommy20]

That doesn't do anything

[Daniel0]

It does anything if it's an illegal filetype...

[Alex]

That doesn't do anything

Probably because of the syntax error, a missing ), try:

$allowedTypes = array(
  "image/jpeg",
  "image/jpg",
);

if(!in_array($uploaded_type,$allowedTypes)) {
  echo "You may only upload jpg picture files.<br>";
} 

[Daniel0]

Heh... that's what you get from blindly copy/pasting things without trying to understand it first I guess.

[PFMaBiSmAd]

And unless stated otherwise, all code that is posted comes with an implied disclaimer that it is an untested example showing how you can do something, not that it is actual, final, tested code that can be directly used for any particular purpose. *

 

[* - kind of the same disclaimer that MS ships with its' products, that this is not actual, final, tested code that can be used for any particular purpose.]