Solution of the simple task: Begin3
This section contains description of solving the following simple task in C++:
Begin3°. The sides a and b of a rectangle are given. Find the area S = ab and the perimeter P = 2(a +
b) of the rectangle.
We shall use Visual Studio 2008 as programming environment, however the same results may be
received in the other C++ environments that are supported by Programming Taskbook:
Visual Studio 2010, 2012, 2013 and Code::Blocks 13.
Creating a template and acquaintance with the task
To create a template of the required task one should use PT4Load tool.
The template created for Visual Studio 2008 consists of several files.
But we need only Begin3.cpp file.
This file will be loaded into the code editor of Visual Studio:
using namespace std;
The file contains the definition of the Solve function, which the solution of the task should be entered in
(of course any other functions may be used).
The Solve function already contains the Task function
call that initializes the Begin3 task.
Note that a header file named pt4.h is included in the Begin3.cpp file. It contains
declarations of additional types and functions, in particular, the GetPut functions.
Definitions of these functions are contained in the pt4.cpp file.
The pt4.h file also contains a definition of the WinMain function, which calls the Solve function.
These files are not loaded into the editor of Visual Studio. But the project
includes the pt4.h and pt4.cpp files (see the Solution Explorer window located on the Visual Studio window).
To run the program press [F5] key (or [F9] in Code::Blocks).
Before compilation of the program the Visual Sudio environment may output the following dialog box
Select "Yes" (it is enough to press [Enter]). When the program is launched
you will see the Programming Task window with a task text and
This running is considered as acquaintance running because
the program does not perform input-output operations.
To close the Programming Taskbook window click the "Exit" button or press [Esc] or [F5]/[F9] key
in Visual Studio/Code::Blocks.
Initial data input
Before solving tasks you should input initial data in the program.
In the Begin3 task the initial data are real numbers a and b
that refer to sides of the rectangle.
The initial data should be input in the variable of the required type, otherwise Programming Taskbook
will detect error. Let's model this situation in our program. For this purpose we shall organize initial data
input to variables of the integer type using the
int a, b;
Run the program once again. You will see the new set of initial data. For each running of the
program a new initial data are generated, so it is necessary to develop an algorithm that processes correctly
all admissible sets of initial data.
In this case the running leads to the following information in the status bar:
"Invalid type is used for an input data item." Note that each type of errors is marked by different color.
To input data correctly we should use the GetD function that
provides input data of double type. Change our program as follows:
double a, b;
Now data input is performed correctly, but the program does not output results.
In such situation we have
the following message: "Correct data input: all required data are input, no data are output"
(Programming Taskbook version 4.15 or higher) or "Some data are not output" (previous versions).
Calculation and output results
Let's perform the required calculations and output results using the PutD
double a, b;
double S = a * b, P = 2 * (a + b);
When the program is running you can see output values at the panel of results.
Because we output data in inverse order, the status bar contains the error message "Wrong solution".
Right solution and its testing
To correct the last error it is enough to change order of two output statements in the Solve function:
When this program is running you will see the testing panel on screen:
This panel appears when the program processes successfully at least one set of input data.
The progress bar shows the amount of tests which are already performed,
the text above the bar allows to determine how much tests should be performed successfully.
The program testing finishes in two cases: when all required tests are performed successfully
or when some test is failed. If the program is in infinite loop then
you should close the testing panel by means of the [x] button in its upper right corner.
In our case the algorithm is correct, therefore the message
"The task is solved!" will be shown.
To browse information about the task solving you can use PT4Results tool
(you may run this tool by pressing the [F2] key or clicking the "Results" label in the upper-right corner of
the Programming Taskbook window):
Begin3 c23/02 20:13 Acquaintance with the task.
Begin3 c04/02 15:07 Invalid type is used for an input data item.
Begin3 c04/02 15:09 Correct data input.
Begin3 c04/02 15:12 Wrong solution.
Begin3 c04/02 15:15 The task is solved!
The letter "c" denotes the programming language being used (C++).
double a, b;
pt >> a >> b;
pt << a * b << 2 * (a + b);