c++ - STL Scope of containers -

i wanted know of scope of stl containers.

for eg. //have function creates unordered_map , passes set_map fill values in it.

int foo() {   unorderd_map<char,int>mymap;   set_map(mymap); }  set_map (unorderd_map<char,int> mmap){ //...setting values of map } 

in case scope of mymap in foo limited function foo() or mymap passed reference set_map() , whatever changes done in set_map reflected mymap in foo() ?

i wanted know how still containers passed function parameters, i.e. passed value or passed reference.

thank you

mymap passed as copy set_map, set_map sees own copy of map, not original mymap. changes made in set_map applied copy, , not affect original mymap.

to pass map reference need declare explicitly:

set_map (unordered_map<char,int>& mmap)                              // ^ passed reference now. 

now changes in set_map alter original object passed parameter.