Why is it wrong to judge whether the sha1 encrypted string after the POST is equal.

Why is it wrong to judge whether the sha1 encrypted string after the POST is equal. For example, the encrypted string 356a192b7913b04c54574d18c28d46e6395428ab is returned in the form post.
Then, if ($ _ POST ['s '] = '356a192b7913b04c54574d18c28d46e6395428ab ')
Why is it false?
Echo $ _ POST ['s'] is also 356a192b7913b04c54574d18c28d46e6395428ab ..

Reply to discussion (solution)

Check whether $ _ POST ['s '] is the value.

Check whether $ _ POST ['s '] is correct... I tried it at BAE .. Why...

You might as well use var_dump () to see if it contains a space line break or something.

You might as well use var_dump () to see if it contains a space line break or something.
No .. And I also used trim () to filter out .. Can you help me check it out. Http://hole.icnu.me/t1.php

I copied his var_dump () output quotation marks + value can be true.
If you open a quotation mark by yourself, it is false... Why ??

You may not have posted your code.

You may not have posted your code.
T. php code ..

 ';var_dump($_POST['set']);if($_POST['set']=="f45918a75f152c9ce0b58043d5e5d7f22358665c")echo 'qw';?>

That is, the double quotation mark in if is used as false by hand .. I don't know why...
Http://hole.icnu.me/t1.php here post to t. php

You may not have posted your code.
It should be encoding problems. The conversion encoding is acceptable ..

You may not have posted your code.
It should be encoding problems. The conversion encoding is acceptable ..

Wrong... I don't know why...

I want to re-describe it...
The sha1 encrypted characters should be 40 characters
After post, how can it become 43 characters ...?
It is also 40 characters to re-encrypt on the following page ..
However, if you directly specify a pointer to the encrypted string, it will be 43 characters long...
Why?

Data from var_dump () post
String (43 )"? 356a192b7913b04c54574d18c28d46e6395428ab"
Var_dump (sha1 ('1 '))
String (40) "356a192b7913b04c54574d18c28d46e6395428ab"
Var_dump ('356a192b7913b04c54574d18c28d46e6395428ab ')
String (43 )"? 356a192b7913b04c54574d18c28d46e6395428ab"

Your echo pack ('H * ', $ _ POST ['set']); check the result.

Your echo pack ('H * ', $ _ POST ['set']); check the result.

Sorry, I made a mistake!
In this way:
Print_r (unpack ('H * ', $ _ POST ['set']);

Sorry, I made a mistake!
In this way:
Print_r (unpack ('H * ', $ _ POST ['set']);

Array ([1] => struct)

Array ([1] => struct)

This efbbbf is the UTF-8 BOM header.
You can remove the BOM header of the relevant file.

Array ([1] => struct)

This efbbbf is the UTF-8 BOM header.
You can remove the BOM header of the relevant file.

Thank you ~~