readdata032.cpp

Data Abstraction & Problem Solving with C++源码

const int LOW_END=10;   // low end of incomes
const int HIGH_END=100; // high end of incomes
const int TABLE_SIZE = HIGH_END - LOW_END + 1;
typedef int TableType[TABLE_SIZE];

int index(int group)
// Returns the array index that corresponds to group number.
{
   return group - LOW_END;
}  // end index

void readData(TableType incomeData)
// ---------------------------------------------------------
// Reads and organizes income statistics.
// Precondition: The calling module gives directions and
// prompts user. Input data is error-free and each input
// line is in the form G N, where N is the number of
// people with an income in the G-thousand-dollar group
// and LOW_END <= G <= HIGH_END. An input line with values
// of zero for both G and N terminates the input.
// Postcondition: incomeData[G-LOW_END] = total number of
// people with an income in the G-thousand-dollar group for
// each G read. The values read are displayed.
// ---------------------------------------------------------
{
   int group, number; // input values

   // clear array
   for (group = LOW_END; group <= HIGH_END; ++group)
      incomeData[index(group)] = 0;

   for (cin >> group >> number;
        (group != 0) || (number != 0);
        cin >> group >> number)
   {  // Invariant: group and number are not both 0
      cout << "Income group " << group << " contains "
           << number << " people.\n";
      incomeData[index(group)] += number;
   }  // end for
}  // end readData