c++ - How do reference_wrapper and std::ref work? -


i trying understand how std::ref works.

#include <functional> #include <iostream>  template <class c> void func(c c){     c += 1; }  int main(){     int x{3};     std::cout << x << std::endl;     func(x);     std::cout << x << std::endl;     func(std::ref(x));     std::cout << x << std::endl; }  output : 3 3 4

in code above, think template parameter c third function call instantiated std::reference_wrapper<int>. while reading the reference, noticed there no += operator in std::reference_wrapper<int>. then, how c += 1; valid?

how c += 1; valid?

because reference_wrapper<int> implicitly convertible int& via conversion operator; , implicit conversions considered operands if there no suitable overload operand type itself.


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