The json_decode function cannot be parsed due to BOM and & lt; feff & gt; encoding in PHP.

Yesterday, my colleague encountered a strange problem: the following code cannot pass JSON verification or parse through the json_decode function of PHP.
Copy codeThe Code is as follows:
[
{
Remark "title ":"",
"Pinyin ":""
}
]

It may be wise that you have guessed that it contains special characters that you cannot see. In vim, View:
Copy codeThe Code is as follows:
[
{
<Feff> "title ":"",
"Pinyin ":""
}
]
It is found that there is a character <feff> in front of the title. If you have learned about BOM before, you should know that this special character is BOM. For more information, see another article: detailed explanation of string encoding, garbled code, BOM, and other issues in the computer.

In Linux, run the xxd command to view the hexadecimal format of the file content:
Copy codeThe Code is as follows:
0000000: 5b 0a 20 20 20 20 7b 0a 20 20 20 20 20 20 [.{.
0000010: ef bb bf 22 74 69 74 6c 65 22 3a 20 22 2c 0a... "title ":"",.
0000020: 20 20 20 20 20 20 22 70 69 6e 79 69 6e 22 "pinyin"
0000030: 3a 20 22 22 0a 20 20 20 7d 0a 5d 0a: "".}.].
We can see that the special character hex before "title" is ef bb bf, which is the BOM marking the UTF-8. The meaning of BOM is as follows:
Copy codeThe Code is as follows:
Character Set/encoding
Ef bb bf UTF-8
Fe ff UTF-16/UCS-2, little endian (UTF-16LE)
Ff fe UTF-16/UCS-2, big endian (UTF-16BE)
Ff fe 00 00 UTF-32/UCS-4, little endian.
00 00 fe ff UTF-32/UCS-4, big-endia

It is easy to solve the problem, and it is OK to find and delete the BOM. The BOM-related commands in linux include:

Vim bom operations
Copy codeThe Code is as follows:
# Add BOM
: Set bomb
# Delete BOM
: Set nobomb
# Query BOM
: Set bomb?

Find BOM in UTF-8 Encoding
Copy codeThe Code is as follows: grep-I-r-l $ '\ xEF \ xBB \ xBF'/path
You can also disable submitting BOM in svn hooks (the following code is from the network and is not verified)
Copy codeThe Code is as follows:
#! /Bin/sh

REPOS = "$1"
TXN = "$2"

SVNLOOK =/usr/bin/svnlook

FILES = '$ SVNLOOK changed-t "$ TXN" "$ REPOS" | awk {'print $2 '}'

For FILE in $ FILES; do
CONTENT = '$ SVNLOOK cat-t "$ TXN" "$ REPOS" "$ FILE "'

If echo $ CONTENT | head-c 3 | xxd-I | grep-q '0xef, 0xbb, 0xbf '; then
Echo "BOM! "1> & 2
Exit 1
Fi
Done
Finally, it is recommended that you do not use notepad in wowdows to automatically add the BOM editor to modify the code, which may cause some problems.