error_reporting() sets the error reporting level of PHP

error_reporting(E_ALL ^ ​​E_NOTICE ^ E_STRICT ^ E_DEPRECATED);
Brothers, help me explain what this line of code means and what error level to set,

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error_reporting(E_ALL ^ ​​E_NOTICE ^ E_STRICT ^ E_DEPRECATED);
Brothers, help me explain what this line of code means and what error level to set,

Check the official PHP documentation to know: error_reporting
The above code means: all errors except E_NOTICE E_SCRICT E_DEPRECATED are reported.
E_ALL ^ ​​E_NOTICE ^ E_STRICT ^ E_DEPRECATED This is a continuous XOR operation.
E_ALL E_NOTICE E_STRICT E_DEPRECATED These are constants, and the corresponding binary numbers are roughly as follows

<code>E_NOTICE 00001 
E_STRICT 00010
E_DEPRECATED 00100
E_ALL 11111
</code>

After performing the XOR operation, it is equivalent to turning the same ones into 0 and the different ones into 1. In other words, the result obtained is that E_ALL excludes those that perform the XOR operation.
The values ​​corresponding to the above constants are purely fictitious. You can try to print them out to see what they are.
Similarly, you can also use methods such as E_NOTICE | E_STRICT to set multiple levels for reporting. The principle is that after the or operation, if there is 1, it is 1, and if there are all 0, it is 0

What this means is: output all types of errors (E_ALL), but exclude E_NOTICE, E_STRICT, and E_DEPRECATED.

A bit operation technique is used here, because E_ALL is an all-1 number, and E_NOTICE, E_STRICT, and E_DEPRECATED are all single-1 numbers. These are XORed to form a log-level number that excludes these items. .