Questions about ob_get_clean

Questions about ob_get_clean

The execution result of this program is hello word everyone.
The strange thing is why ob_start () does not need to be declared ()

Reply to discussion (solution)

What I see on the Internet is:
Ob_start () indicates opening the buffer. the write-not-write relationship is not very large. it is added here according to the PHP Standard writing method.

The buffer is enabled by default.
You can use ob_get_level () to observe

The buffer is enabled by default.
You can use ob_get_level () to observe

So ~

You can look at this

// Ob_start (); echo 12345; $ out1 = ob_get_clean (); echo "hello word"; $ out = ob_get_clean (); echo $ out. $ out1;