c-resources/CPlusPlus20ForProgrammers-m.../examples/ch09/fig09_16-18/fig09_18.cpp

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// fig09_18.cpp
// public member function that
// returns a reference to private data.
#include <iostream>
#include <fmt/format.h>
#include "Time.h" // include definition of class Time
int main() {
Time t{}; // create Time object
// initialize hourRef with the reference returned by badSetHour
int& hourRef{t.badSetHour(20)}; // 20 is a valid hour
std::cout << fmt::format(
"Valid hour before modification: {}\n", hourRef);
hourRef = 30; // use hourRef to set invalid value in Time object t
std::cout << fmt::format(
"Invalid hour after modification: {}\n\n", t.getHour());
// Dangerous: Function call that returns a reference can be
// used as an lvalue! POOR PROGRAMMING PRACTICE!!!!!!!!
t.badSetHour(12) = 74; // assign another invalid value to hour
std::cout << "After using t.badSetHour(12) as an lvalue, "
<< fmt::format("hour is: {}\n", t.getHour());
}
/**************************************************************************
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* *
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