CBSE Class 11 Computer Science Programming In C++ Notes

Programming in C++

Investigation of Programming Construct in C++.

OBJECTIVES :

• to emphasize the programming construct available in C++

• to investigate each and every programming construct emphasizing the situation where they can be used perfectly.

• to demonstrate few working program in C++ using the constructs.

1.1 Why and What of Constructs in C++ programming

1.1.1 : Flow of logic

You have seen in the previous unit that a program is implementation of an algorithm (steps involved in problem solving) using a particular programming language like C , C++ , Java etc. In our case we are using C++ as a high level language (HLL) to code our programs.

A programming language like C++ is having a bundle of programming elements like tokens , identifiers , variables , constants , operator symbols , punctuation symbols etc. (please refer to earlier unit if you have not learnt all these terms.) . All these programming elements helps a programmer to write simple C++ programs as shown below :

program 1.1

// a simple program in C++ to add two integers

#include<iostream.h>

void main( )

{

int a = 0 , b = 0 ;

cout<<”Input two numbers”;

cin>> a>>b;

cout<<”The sum of numbers are: ” << (a+b);

}

The above program is a very basic program which asks two integer values from user and prints out their sum. In the above program you may observe that various programming elements like:

                         # < ( ) { = , a b << >> int void main ―Input two numbers ― ; are being used.

Students the program above is very simple to be thought , written and executed, but in real industrial programming situation we seldom get such programs to write. There are many complex situation in life where we often need to write programs using few advanced programming elements. Let us investigate few of the real life situations :

a) Ram needs to find out whether any number is divisible by both 3 and 5.

b) A shopkeeper wants to give x % discount on a particular purchase only when the net purchase by his customer exceeds Rs. 1000

c) A teacher wants to calculate the average marks for each of his 40 pupils in a class.

d) Suresh wants to continue his program till he is pressing escape button on keyboard.

Can you program the above programming problems using the programming elements of C++ which you have learn till now ?

Your answer would be probably a NO , because the C++ programming elements which you have studied till now , will only enable you to write simple linear programs , or sequential programs.

1.1.2: Linear Flow

A simple linear program is one which has a linear flow of execution of programming logic /statements. e.g. program 1.1. The logic of program flows ( or better they are termed as control flow) from top to bottom out of set of statements.

Now let us proof the that program 1.1 follows a sequential flow of logic by the following flow chart diagram :

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