fig02_09.cpp

《c＋＋大学教程》源码

// Fig. 2.9: fig02_09.cpp
// Class average program with sentinel-controlled repetition.
#include <iostream>

using std::cout;
using std::cin;
using std::endl;
using std::fixed;        

#include <iomanip>        // parameterized stream manipulators

using std::setprecision;  // sets numeric output precision

// function main begins program execution
int main()
{
   int total;         // sum of grades
   int gradeCounter;  // number of grades entered
   int grade;         // grade value

   double average;    // number with decimal point for average

   // initialization phase
   total = 0;         // initialize total
   gradeCounter = 0;  // initialize loop counter

   // processing phase
   // get first grade from user
   cout << "Enter grade, -1 to end: ";  // prompt for input
   cin >> grade;                        // read grade from user

   // loop until sentinel value read from user
   while ( grade != -1 ) {                  
      total = total + grade;            // add grade to total
      gradeCounter = gradeCounter + 1;  // increment counter
      
      cout << "Enter grade, -1 to end: ";  // prompt for input
      cin >> grade;                        // read next grade

   } // end while

   // termination phase
   // if user entered at least one grade ...
   if ( gradeCounter != 0 ) {
      
      // calculate average of all grades entered
      average = static_cast< double >( total ) / gradeCounter;
      
      // display average with two digits of precision
      cout << "Class average is " << setprecision( 2 )
           << fixed << average << endl;

   } // end if part of if/else

   else // if no grades were entered, output appropriate message
      cout << "No grades were entered" << endl;

   return 0;   // indicate program ended successfully

} // end function main


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 * (C) Copyright 1992-2003 by Deitel & Associates, Inc. and Prentice      *
 * Hall. All Rights Reserved.                                             *
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