fig07_05.cpp

来自「《c＋＋大学教程》源码」· C++ 代码 · 共 75 行

// Fig. 7.5: fig07_05.cpp
// Attempting to initialize a constant of
// a built-in data type with an assignment.
#include <iostream>

using std::cout;
using std::endl;

class Increment {

public:
   Increment( int c = 0, int i = 1 );  // default constructor

   void addIncrement() 
   { 
      count += increment; 

   } // end function addIncrement

   void print() const;     // prints count and increment

private:
   int count;
   const int increment;    // const data member

}; // end class Increment

// constructor 
Increment::Increment( int c, int i )
{             // Constant member 'increment' is not initialized
   count = c;      // allowed because count is not constant
   increment = i;  // ERROR: Cannot modify a const object

} // end constructor Increment

// print count and increment values
void Increment::print() const
{
   cout << "count = " << count
        << ", increment = " << increment << endl;

} // end function print

int main()
{
   Increment value( 10, 5 );

   cout << "Before incrementing: ";
   value.print();

   for ( int j = 0; j < 3; j++ ) {
      value.addIncrement();
      cout << "After increment " << j + 1 << ": ";
      value.print();
   }

   return 0;

} // end main

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