Is there something wrong with my comments? Why does the final result output 13?

Question

Is there something wrong with my annotation?

Answer 1

It’s indeed 13. You may have misread that place. Please take a look

Answer 2

Basic rules: ++ is in front, add first and then perform operations; ++ is in the back, perform operations first and then add.

$foo = 5+5; Equal to 6;

$cup = 6+7; x and y are calculated first and then decremented, x=5, y=6;

$paper = 6+6; first + + is in front of x, first add 1, x=6; the second ++ is after x, then add one after the operation, x=7;

$water = 6+7=13; two --are after the variable, the expression will be decremented after the operation is completed, x=6, y=5;