By Dr. Fotis Liarokapis 1
Introduction to C++ (Part I)
Welcome to the first laboratory session which will introduce you to C++.
Setting Up
First start Microsoft Visual C++. Then go to File->New Project. This will open the
project window. Then select Win32->Win32 Console Application, and enter the directory
that you want to store the source code as well as the name of source file. Select as
Tutorial 1 for the name of the directory and as tutorial 1 for the name of the source file as
shown from the figure below.
Next, follow the wizard and leave the default options as shown from the screenshots
below.
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Congratulations, up not now you have created your first C++ program without writing
any code. To see what you have done, press Ctrl+F5 to execute the application. When
you do that you should get an empty MS-DOS window.
However, if you prefer to write everything from scratch you can do it! Close that
workspace by selecting File->Close Solution. Try creating a new project (File->New
Project) but in this case select General->Empty project, as shown from the screenshot
below.
Input a new directory name (call it Tutorial 1 Empty) and specify a name (call it main).
Right-click on the main solution (which can be found on the Solution Explorer) and
select the Rebuilt Solution from the drop-down menu. You should get a message like the
one shown below:
1>------ Rebuild All started: Project: main, Configuration: Debug Win32 ------
1>Deleting intermediate and output files for project 'main', configuration 'Debug|Win32'
1>main - up-to-date
========== Rebuild All: 1 succeeded, 0 failed, 0 skipped ==========
Next right-click again on the main solution and select the Add->New Item option as
shown from below.
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Then from the menu, select C++ File (.cpp), and choose the name main again as shown
below.
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If you try to ‘Rebuilt’ the solution, you will get an error since there is nothing included in
the main.cpp file. The next step is to add the necessary code to open the MS-DOS
window again. This can be done by typing:
int main()
{
}
Try to rebuilt and execute the application by pressing Ctrl+F5.
Now it is time to start writing some code!
Example 1: Print a String on the Screen
First include the standard C++ library (iostream) and add some comments. To include the
iostream library type the following:
#include <iostream>
using namespace std;
Note that we use cin.get() which is another function call: it reads in input and expects the
user to hit the return key. So, inside the main function type the following code:
cout<<"PHYSICS FOR COMPUTER GRAPHICS! My first C++ program!\n";
cin.get();
return 1;
Now, rebuilt and execute the solution. Change the text string to something else. You can
also try the same code in the Win32 console application.
Example 2: Get User Input
In this example we need to demonstrate how to get input from the user and print it on the
screen. One of the first things that we need to do is to define a variable, which will hold
the data. In this example, we call the variable number and declare it as integer type. The
function cin>> reads a value into number; the user must press enter before the number is
read by the program. cin.ignore() is another function that reads and discards a character.
Remember that when you type input into a program, it takes the enter key too. We don't
need this, so we throw it away.
int number;
cout<<"Please enter an interger number: ";
cin>> number;
cin.ignore();
cout<<"User has entered: "<< number <<"\n";
cin.get();
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return 1;
Now, rebuilt and execute the solution.
Example 3: If Statements
Without a conditional statement such as the if statement, programs would run almost the
exact same way every time. If statements allow the flow of the program to be changed,
and so they allow algorithms and more interesting code. Moreover, a true statement is
one that evaluates to a nonzero number. A false statement evaluates to zero. When you
perform comparison with the relational operators, the operator will return 1 if the
comparison is true, or 0 if the comparison is false. To get a better idea type the following
code.
int age;
cout<<"Please input your age: "; // Enter the age
cin>> age; // The input is stored in age variable
cin.ignore(); // Throw away enter
if ( age < 100 ) // If the age is less than 100
{
cout<<"You are pretty young!\n";
}
else if ( age == 100 )
{
cout<<"You are old\n";
}
else
{
cout<<"You are really old\n";// Executed if no other statement is
}
cin.get();
return 1;
Now, rebuilt and execute the solution.