Consider using auto as a placeholder for the actual type in the following situations:

• To declare local variables with the form auto name = expression when you do not want to commit to a specific type:

        auto i = 42;          // int 
        auto d = 42.5;        // double 
        auto s = "text";      // char const * 
        auto v = { 1, 2, 3 }; // std::initializer_list<int> 

• To declare local variables with the auto name = type-id { expression } form when you need to commit to a specific type:

        auto b  = new char[10]{ 0 };            // char* 
        auto s1 = std::string {"text"};         // std::string
        auto v1 = std::vector<int> { 1, 2, 3 }; // std::vector<int>
        auto p  = std::make_shared<int>(42);    // std::shared_ptr<int>

• To declare named lambda functions, with the form auto name = lambda-expression, unless the lambda needs to be passed or return to a function:

        auto upper = [](char const c) {return toupper(c); };

• To declare lambda parameters and return values:

        auto add = [](auto const a, auto const b) {return a + b;};

• To declare function return type when you don't want to commit to a specific type:

        template <typename F, typename T> 
        auto apply(F&& f, T value) 
        { 
          return f(value); 
        }