fig05_06.cpp

// fig05_06.cpp
// Scoping example.
#include <iostream>
using namespace std;

void useLocal(); // function prototype
void useStaticLocal(); // function prototype
void useGlobal(); // function prototype

int x{1}; // global variable

int main() {
   cout << "global x in main is " << x << '\n';

   const int x{5}; // local variable to main

   cout << "local x in main's outer scope is " << x << '\n';

   { // block starts a new scope                               
      const int x{7}; // hides both x in outer scope and global x   

      cout << "local x in main's inner scope is " << x << '\n';
   }

   cout << "local x in main's outer scope is " << x << '\n';

   useLocal(); // useLocal has local x
   useStaticLocal(); // useStaticLocal has static local x
   useGlobal(); // useGlobal uses global x
   useLocal(); // useLocal reinitializes its local x
   useStaticLocal(); // static local x retains its prior value
   useGlobal(); // global x also retains its prior value

   cout << "\nlocal x in main is " << x << '\n';
}

// useLocal reinitializes local variable x during each call
void useLocal() {
   int x{25}; // initialized each time useLocal is called

   cout << "\nlocal x is " << x << " on entering useLocal\n";
   ++x;
   cout << "local x is " << x << " on exiting useLocal\n";
}

// useStaticLocal initializes static local variable x only the
// first time the function is called; value of x is saved
// between calls to this function
void useStaticLocal() {
   static int x{50}; // initialized first time useStaticLocal is called

   cout << "\nlocal static x is " << x 
      << " on entering useStaticLocal\n";
   ++x;
   cout << "local static x is " << x << 
      " on exiting useStaticLocal\n";
}

// useGlobal modifies global variable x during each call
void useGlobal() {
   cout << "\nglobal x is " << x << " on entering useGlobal\n";
   x *= 10;
   cout << "global x is " << x << " on exiting useGlobal\n";
}

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