PHP logical operator. Solution Solutions

PHP logic operator ...
There are two problems when judging the file type. The code is as follows:
if ($type!== ' gif ' | | $type!== ' JPEG ' | | $type!== ' png ') {
echo "Format error";
}
else {
Echo $type;
}
Question 1: Not equal, is with!==?
Issue 2: | | It doesn't work, or it's useless to change it. If only one can be judged, the explanation is not equal to the correct.
but | | Why not work, this if in C # but absolutely workable AH.
------Solution--------------------
1 can be expressed in! =, can also be expressed with!==, the specific difference between the mother
2 you mean as long as the type is gif,jpeg,png to judge correctly?
That should be written like this: if ($type!== ' gif ' && $type!== ' jpeg ' && $type!== ' png ')
------Solution--------------------
The!== operator is all equal to the negative usage of ' = = = ', which distinguishes values, data types, capitalization, etc.
Just change to this! =.
------Solution--------------------
Question 1: Not equal, is with!==?
! = is not equal to
!== Not all equal to

Question 2:
------Solution--------------------
It doesn't work, or it's useless to change it.
You need to use and && logic to judge.

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