77 lines
2.8 KiB
C++
77 lines
2.8 KiB
C++
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// fig11_06.cpp
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// C++20 three-way comparison (spaceship) operator.
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#include <compare>
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#include <fmt/format.h>
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#include <iostream>
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#include <string>
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class Time {
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public:
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Time(int hr, int min, int sec) noexcept
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: m_hr{hr}, m_min{min}, m_sec{sec} {}
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std::string toString() const {
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return fmt::format("hr={}, min={}, sec={}", m_hr, m_min, m_sec);
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}
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// <=> operator automatically supports equality/relational operators
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auto operator<=>(const Time& t) const noexcept = default;
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private:
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int m_hr{0};
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int m_min{0};
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int m_sec{0};
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};
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int main() {
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const Time t1(12, 15, 30);
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const Time t2(12, 15, 30);
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const Time t3(6, 30, 0);
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std::cout << fmt::format("t1: {}\nt2: {}\nt3: {}\n\n",
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t1.toString(), t2.toString(), t3.toString());
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// using the equality and relational operators
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std::cout << fmt::format("t1 == t2: {}\n", t1 == t2);
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std::cout << fmt::format("t1 != t2: {}\n", t1 != t2);
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std::cout << fmt::format("t1 < t2: {}\n", t1 < t2);
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std::cout << fmt::format("t1 <= t2: {}\n", t1 <= t2);
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std::cout << fmt::format("t1 > t2: {}\n", t1 > t2);
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std::cout << fmt::format("t1 >= t2: {}\n\n", t1 >= t2);
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std::cout << fmt::format("t1 == t3: {}\n", t1 == t3);
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std::cout << fmt::format("t1 != t3: {}\n", t1 != t3);
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std::cout << fmt::format("t1 < t3: {}\n", t1 < t3);
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std::cout << fmt::format("t1 <= t3: {}\n", t1 <= t3);
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std::cout << fmt::format("t1 > t3: {}\n", t1 > t3);
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std::cout << fmt::format("t1 >= t3: {}\n\n", t1 >= t3);
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// using <=> to perform comparisons
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if ((t1 <=> t2) == 0) {
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std::cout << "t1 is equal to t2\n";
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}
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if ((t1 <=> t3) > 0) {
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std::cout << "t1 is greater than t3\n";
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}
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if ((t3 <=> t1) < 0) {
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std::cout << "t3 is less than t1\n";
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}
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}
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/**************************************************************************
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* (C) Copyright 1992-2022 by Deitel & Associates, Inc. and *
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* Pearson Education, Inc. All Rights Reserved. *
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* *
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* DISCLAIMER: The authors and publisher of this book have used their *
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* best efforts in preparing the book. These efforts include the *
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* development, research, and testing of the theories and programs *
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* to determine their effectiveness. The authors and publisher make *
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* no warranty of any kind, expressed or implied, with regard to these *
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* programs or to the documentation contained in these books. The authors *
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* and publisher shall not be liable in any event for incidental or *
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* consequential damages in connection with, or arising out of, the *
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* furnishing, performance, or use of these programs. *
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**************************************************************************/
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