c-resources/CPlusPlus20ForProgrammers-m.../examples/ch20/fig20_03.cpp

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// fig20_03.cpp
// Demonstrating namespaces.
#include <fmt/format.h>
#include <iostream>
int integer1{98}; // global variable
// create namespace Example
namespace Example {
// declare two constants and one variable
const double pi{3.14159};
const double e{2.71828};
int integer1{8};
void printValues(); // prototype
// nested namespace
namespace Inner {
// define enumeration
enum Years { fiscal1 = 2020, fiscal2, fiscal3 };
}
}
// create unnamed namespace
namespace {
double doubleInUnnamed{88.22}; // declare variable
}
int main() {
// output value doubleInUnnamed of unnamed namespace
std::cout << fmt::format("doubleInUnnamed = {}\n", doubleInUnnamed);
// output global variable
std::cout << fmt::format("(global) integer1 = {}\n", integer1);
// output values of Example namespace
std::cout << fmt::format(
"pi = {}\ne = {}\ninteger1 = {}\nfiscal3 = {}\n", Example::pi,
Example::e, Example::integer1, Example::Inner::fiscal3);
Example::printValues(); // invoke printValues function
}
// display variable and constant values
void Example::printValues() {
std::cout << "\nIn printValues:\n";
std::cout << fmt::format(
"integer1 = {}\npi = {}\ne = {}\n", integer1, pi, e);
std::cout << fmt::format(
"doubleInUnnamed = {}\n(global) integer1 = {}\nfiscal3 = {}\n",
doubleInUnnamed, ::integer1, Inner::fiscal3);
}
/**************************************************************************
* (C) Copyright 1992-2022 by Deitel & Associates, Inc. and *
* Pearson Education, Inc. All Rights Reserved. *
* *
* DISCLAIMER: The authors and publisher of this book have used their *
* best efforts in preparing the book. These efforts include the *
* development, research, and testing of the theories and programs *
* to determine their effectiveness. The authors and publisher make *
* no warranty of any kind, expressed or implied, with regard to these *
* programs or to the documentation contained in these books. The authors *
* and publisher shall not be liable in any event for incidental or *
* consequential damages in connection with, or arising out of, the *
* furnishing, performance, or use of these programs. *
**************************************************************************/