how to use this shortcut?

[yozloy]

I've see this in espresso, Is there anybody can tell my how to use this?
Thanks

 

[LPZ]

I've see this in espresso, Is there anybody can tell my how to use this?
Thanks

Can't make much sense of your image, but if you're asking about

(condition)? expr : expr

it might be used like this:

min_of_a_and_b = ( a < b )? a : b

or like this

absolute_value_of_x = ( x < 0 )? -x : x

 

[angelwatt]

I believe that symbol is for the tab key.