PROGRAM 61

Object

Write a program to calculate average marks of a student using for and nested while loop.

Algorithm

1. Declare integer variables n and count and float variables marks, average and sum.
2. Set sum = 0.
3. Read n.     [number of subjects.]
4. Repeat FOR count = 1 to n
   • Read marks of n subjects.
     • Repeat WHILE marks are < 0 or > 100
       • Write Invalid marks, try again.
       • Read marks.
       • [End of WHILE loop.]
   • sum = sum + marks.
   • [End of FOR loop.]
5. average = sum/n.
6. Write average.
7. Exit.

Flowchart

C++ Source Code

// program 61
#include<iostream>
using namespace std;

int main()
{
  int n, count;
  float marks, average, sum = 0;

  // Read in a value for n
  cout << "How many Subjects? ";
  cin >> n;
  cout << endl;

  // Read marks
  for (count = 1; count <= n; count++)
  {
    cout << "Marks in Subject " << count << " = ";
    cin >> marks;

    while (marks < 0 || marks > 100)
    {
      cout << "Invalid marks, try again: ";
      cin >> marks;
    }
    sum += marks;
  }

  // Calculate the average and print the answer
  average = sum / n;
  cout << "\nThe average marks are = " << average << endl;
  return 0;
}

C Source Code

/*program 61*/
#include<stdio.h>

int main()
{
  int n, count;
  float marks, average, sum = 0;

// initialise and read in a value for n
  printf("How many Subjects? ");
  scanf("%d", &n);
  printf("\n");

// read marks
  for(count =1; count <= n; count++)
     {
     printf("Marks in Subject %d = ", count);
     scanf("%f", &marks);
     while(marks < 0 || marks > 100)
	  {
	  printf("Invalid marks, try again: ");
	  scanf("%f", &marks);
	  }
     sum += marks;
     }

// calculate the average and print the answer
  average = sum/n;
  printf("\nThe average marks are = %.2f", average);
  return 0;
}

Output

How many Subjects? 5

Marks in Subject 1 = 69
Marks in Subject 2 = 58.8
Marks in Subject 3 = 37
Marks in Subject 4 = 83
Marks in Subject 5 = 65

The average marks are = 62.56