std::placeholders Symbol Index
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                    < cpp | symbol index
                    
                                                            
                    
This page tries to list all the symbols that are available from the standard library in the namespace std::placeholders. The symbols are written as follows:
-  Function names with 
(). -  Templates with 
<>. 
_
_
_ (underscore)
_1, _2, ..., _N (since C++11)