Php explains why isset () is used ()

Php explains why isset () is used () by default, the PHP error reporting level is not the highest, which leads to some small errors, but we cannot see the errors. according to the practice, it is found that these small errors will affect the PHP execution speed and execution speed! @ Suppress error. it does not mean that no error is generated. error_reporting (8191) starts. # explain the error in php to why isset () is used ()
The PHP error reporting level is not the highest by default.
This will cause some minor errors, but we will not see them.
According to the practice, it is found that PHP's small errors will affect the PHP's high execution speed and high execution speed!
@ Suppress error. no error is generated.

Start

Error_reporting (8191); # adjust the error reporting level to the highest

Echo $ a; # an error occurs. $ a is not defined in advance.

Echo @ $ a; # Nothing

Finally, the speed test on isset and @ found that after the execution of 1000 times

Isset Time: 0.0008 ± 0. 0001 seconds
@ Takes 0.002 seconds


If no reason is found, the default error level is directly set.

If ($ a) loops for 1 million times
And
If (isset ($ a) loops for 1 million times

It's not a little faster