Page 104 - Computer Science Class 11 With Functions
P. 104

To deal with situations when you do not know in advance the number of times a loop is to be executed, the programming
        languages  provide  a  while  construct.  Using  a  while-loop,  let  us  develop  a  pseudocode  to  output  the  average
        marks of students. As we do not know the number of students, we need to keep count of the number of students
        (say, nStudents). To begin with, we set
            nStudents = 0
        Further, we need to sum the marks (say, sumMarks) obtained by the  students. Again set
            sumMarks = 0
        Next, while the user enters marks >0,  we continue to increment the student count (nStudents), add marks to
        the accumulated sum of marks (sumMarks), and read marks for the next student. Finally, we divide sumMarks by
        nStudents to get average marks and report the result to the user. We present the foregoing discussion in the
        form of pseudocode:
        sumMarks = 0
        nStudents = 0
        Input marks
        while marks >0:
            nStudents = nStudents + 1
            sumMarks = sumMarks + marks
            Input marks
        end-while
        average = sumMarks/nStudents
        print(average)

             Let's Summarise


          Ø   Programming language is a language that a computer understands.
          Ø   Program (code) is a sequence of instructions in a programming language for solving a problem.

          Ø   The process of dividing a complex problem into subproblems, solving the subproblems, and merging the
              solutions to the subproblems to solve the original problem is called the modular approach.

          Ø   An algorithm is a sequence of steps to be followed in solving a problem.
          Ø   A flowchart is a pictorial representation of an algorithm. Some common symbols used in a flowchart are as
              follows:

                   Symbol Name           Symbol usage                         Description

                                     Start/Stop            Used to depict the start and stop of an algorithm


                                     Process               Used to depict some arithmetic operation

                                     Input/Output          Used to depict Read/Input and Write/Print



                                     Arrow                 Used to connect shapes depicting the flow of control




                                     Decision box          Represents a condition that may yield True or False.




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