Page 104 - Computer Science Class 11 Without Functions
P. 104

Finally, suppose you are required to find the average marks of students in a class. The marks obtained by different
               students are entered by the user one by one, and the end of the input is indicated by entering a negative integer. 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




         102   Touchpad Computer Science-XI
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