cs101 ОП / Basics of programming ENG

Be sure to read the requirements for labs.

[`task-01.pas` ] Examine the example, create a file with this program and run it.

// The program that outputs the greeting - this is a comment to the program
program Hello;
 begin
  Writeln('Hello world');
end.

Definition of variable

In Pascal abc.net variables may be defined within the body of the program between begin and end.  The principle of locality: the variable is defined immediately before its use.

In traditional pascal:

var n: integer;
begin
  n:=1; // assignment statement

pascalabs.net:

1 method:

begin
  var n:integer;
  n:=1;

begin
  var n:=1;

Arithmetic operations, assigning value to a variable and expressions

common method:

begin
  var a := 6; // Assigning value 6
  a:= a + 2; // Increase by 2
  a:= a - 2; // Reduction of 2
  a:= a * 3; // Multiplication by 3
  a:= a / 2; // division
end.

short method:

begin
  var a := 6; // Assigning value 6
  a+= 2; // Increase by 2
  a-= 2; // Reduction of 2
  a*= 3; // Multiplication by 3
  a/= 2; // division
end.

Data input

1.

begin
  var n:integer;
  read(n);

begin
  var n:real;
  read(n);

var n:=ReadInteger();
var n:=ReadReal();

(n1, n2) := (1, 2);

var(n1, n2) := readInteger2;

Data output:

1 method:

begin
  var n:integer;
  read(n);
  n: = n * n;
  writeln('n = ',n);

begin
  begin
  var n:integer;
  read(n);
  n: = n * n;
  print('n = ',n);

Tasks

Follow the rules:

• Save your files with names as it is given in tasks (e.g. task-04.pas).
• Give meaningfull names to your variables.
• Use comments to make the program clear.
• Give the task of the program in the form of a comment before the program code. For comments use curly brackets: 

• Give the results of your program (log) as a comment after the program code. It’s easy to do just by copying. Use curly brackets to add comments :
  
  

Example

Here is an example of right program which is clear for user:

The resulting example:

Input x 
3
Input y 
4
Input z 
5
The result = 1.77800712886037

 [task-000.pas] Calculate the value of the function y = 4(x-3)^6 - 7(x-3)^3 + 2 , if x=5.

Note. Use the aúxiliary variable for (x-3)^3. Give the program log in the form of a comment.

begin
  Writeln('the side length of a square:');
// Variable declaration to store the value of the side length
  var a := ReadReal;
// Perimeter calculation
  var P := 4 * a;
   Writeln('Perimeter P = ', P);
end.

[task-002.pas]  The diameter of a circle (d) is given. Find its length: L = π·d. The value of π is 3.14. Use different methods of assigning, input and output.

[task-003.pas] Two numbers a and b are given . Find their average: (a + b)/2. Use different methods of assigning, input and output.

  !   [task-004.pas] Calculate hypotenuse  and perimeter of a right-angled triangle, legs of triangle is given (root of (a² + b²)) .

Here is an example of right program which is clear for user:

Possible result:

Input the values of triangle legs:
3
6
hypotenuse = 6.70820393249937
perimeter = 15.7082039324994

  !   Make the next program using the same style of coding. Pay attention to the names of the variables (they have meaning names, that shows the variables’ task in the program):

[extra-task-03.pas] Modify previous program about the cube using this way of variable definition and clear (meaning) variables’ names.

[extra-task-04.pas] Find the distance between two points on the plane; coordinates (x1,y1) and (x2,y2) are given. The distance is calculated by the formula:

Check: Check the correctness of your program with "simple" values that are easily to calculate. For example:

    
d((0,  0); (6, 0)) = 6;
    
d((0,  -4); (0, 1)) = 5;
    
d((-1,  1); (2, 5)) = 5.

Give the results of your program (log) in the form of a comment after the program code. It’s easy to do by simply copying. For comments use curly brackets:

[task-007.pas] The temperature in Celsius is given, convert temperature to Fahrenheit. Celsius and Fahrenheit scales are related by the ratio:

The input/output operators and assignment operator

Examine the examples at the link. Make the programm when it's needed.

begin
  Writeln('Enter the lengths of the legs (two numbers separated by a space):');
// Variable declaration for storing the legs
  var a, b: real;
 // Input. This form is shorter than the ReadReal function, if there are several variables
  Read(a, b);
   var c := sqrt(a*a + b*b);
   Writeln('Hypotenuse c = ', c);
//Calculation of the perimeter of a triangle.
  var P := a + b + c;

Calculation the value of an expression.

1. [task-02.pas] Cálculate the sine and cosine of the angle given in radians.

   Note. If necessary, use the help for mathematical functions: in menu Help / Помощь/Справка — «Справочник по языку» — «Системный модуль PABCSystem» — «Математические подпрограммы».

2. {2 points} [task-03.pas] Cálculate the value of the lógarithm of 1024 to base 2, using the ln, function that calculates the natural logarithm of a given number, and the formula:

   \[\log_a b = \frac{\ln b}{\ln a}\]

3. [task-04.pas] Cálculate the value of the expression:

   \[\frac{x + \sin x}{y - \sin z} + \ln{(x + \sin x)}\]

4. [task-05.pas]Find the distance between two points with given coórdinates \((x_1, y_1)\) и \((x_2, y_2)\) on the plane. The distance is cálculated by the formula \(d=\sqrt{(x_1 - x_2)^2 + (y_1 - y_2)^2}\).

   Check. Check the correctness of your program on "simple" values that are easily counted manually. For example::
   • d((0, 0); (6, 0)) = 6;
   • d((0, -4); (0, 1)) = 5;
   • d((-1, 1); (2, 5)) = 5.

   Give the results (log) of your program in the output window PascalABC.NET in the form of a comment after the program code. It’s easy to do by simply copying.

5. {2.5 points} [task-06.pas] Calculate the value of the function \(y = 4(x-3)^6 - 7(x-3)^3 + 2\) for several given x (that is, run the program several times for different values of x).

   Note. Use the aúxiliary variable for \((x-3)^3\). Give the program log in the form of a comment.

6. [task-7.pas] The temperature in Celsius is given, convert temperature to Fahrenheit. Celsius and Fahrenheit scales are related by the ratio:

\[t^{\circ}C = \frac{5}{9}(t^{\circ}F-32)\]

Проверка. Check here WolframAlpha. Use the following query : convert 5 Celsius to Fahrenheit. Give the log of the programm.

7. {Mark: 3} [task-8.pas] The radii of two concentric circles are given. Calculate the area of the ring enclosed between them.

Extra tasks

8. [task-9.pas] The length of the cube edge a is given. Find the volume of the cube and its surface area. Give the program log in the form of a comment.

9. [task-10.pas] The perimeter of the réctángle and the length of its diágonal are known. Find the sides of the rectangle. Give the program log in the form of a comment.