trigraphs - meaning of `???-` in C++ code -

this question has answer here:

• what c ??!??! operator do? 4 answers

i saw following code legacy codes:

 size_t = 1 ???- 2 :0; 

what symbol ???- mean in c++? how should understand it?

thank you!

it's actually:

size_t = 1 ? ~2 :0; 

??- trigraph ~

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trigraphs old era... before of born.

back in days, there characters weren't supported. unknowing programmer try type in such character find doesn't exist on keyboard!

_{image source: http://www.myoldmac.net/cgi-data/forum/phpbb2/viewtopic.php?t=305}

so trigraphs added allow programmer access functionality of these characters when didn't exist (either in encoding or keyboard).

nowadays, obsolete , more effective in confusing reader in getting around old standards.

so either code old, or author being jerk.