Indexed Variables as Function Arguments

1. An indexed variable of an array can also be used as actual arguments of a function. For example, if exam_score is an array which stores the exam scores as integers. Suppose letter_grade is a function that takes an integer argument that represents an exam score and returns a character that is the letter grade computed based on that score, then the letter grade for the third exam score can be output to the screen as follows:
   
   cout << "The grade for the third exam score is: "
        << letter_grade(exam_score[2]) << endl;
   
   
2. //Illustrates the use of an indexed variable as an argument.
   //Adds 5 to each employee's allowed number of vacation days.
   #include <iostream>
   using namespace std;
   
   const int NUMBER_OF_EMPLOYEES = 3;
   
   int adjust_days(int old_days);
   //Returns old_days plus 5.
   
   int main( )
   {
       int vacation[NUMBER_OF_EMPLOYEES], number;
   
       cout << "Enter allowed vacation days for employees 1"
               << " through " << NUMBER_OF_EMPLOYEES << ":\n";
       for (number = 1; number <= NUMBER_OF_EMPLOYEES; number++)
           cin >> vacation[number-1];
   
       for (number = 0; number < NUMBER_OF_EMPLOYEES; number++)
           vacation[number] = adjust_days(vacation[number]);
   
       cout << "The revised number of vacation days are:\n";
       for (number = 1; number <= NUMBER_OF_EMPLOYEES; number++)
           cout << "Employee number " << number
                   << " vacation days = " << vacation[number-1] << endl;
   
       return 0;
   }
   
   int adjust_days(int old_days)
   {
       return (old_days + 5);
   }