Telerik School Academy
Meeting #1 – November 2010 – Intro to C#
Homework Assignments
Svetlin Nakov
Telerik Corporation
www.telerik.com
Prepare IT Test
Questions
Prepare IT Test Questions
 Prepare at least 20 questions for preparation
for the National Olympiad's IT test
 Prepare at least one question for each category
from the official conspectus
 Categories are officially published at
http://edusoft.fmi.unisofia.bg/documents/Conspect0910.pdf
 Follow strictly the IT test template: IT-TestQuestions-Template.pptx
3
.NET Framework Overview
.NET Framework
1.
Install at home .NET Framework 4 and
Microsoft Visual Studio 2010 (or VS Express)
 Write a "Hello World" application in C#
2.
Install at home the .NET Reflector
 Play with it by decompiling the
System.Console class
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C# Language Overview
C# Language Overview
1.
Write a C# program that prints all numbers 1…100.
2.
Write a program that prints all the numbers from 1 to
N, that are not divisible by 3 and 7.
3.
Write a program that reads from the console a
sequence of N integer numbers and returns the
minimal and maximal of them.
4.
Write a program that calculates N!/K! for given N and
K (1<N<K).
5.
Write a program that reads a number N and
calculates the sum of the first N members of the
sequence of Fibonacci: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34,
55, 89, 144, 233, 377, …
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C# Language Overview (2)
6.
Write a program that finds the maximal sequence of
equal elements in an array.
Example: {2, 1, 1, 2, 3, 3, 2, 2, 2, 1}  {2, 2, 2}.
7.
9.
10.
Write a program that finds the maximal increasing
sequence of elements in an array. Example:
{3, 2, 3, 4, 2, 2, 4}  {2, 3, 4}.
Write a program that finds the most frequent
number in an array. Example:
{4, 1, 1, 4, 2, 3, 4, 4, 1, 2, 4, 9, 3}  4 (5 times)
Write a program that finds all prime numbers in the
range [1...10 000 000]. Use the sieve of Eratosthenes
algorithm (find it in Wikipedia).
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C# Language Overview (3)
11.
Write a program that prints to the console which
day of the week is today. Use System.DateTime.
12.
Write methods that calculate the surface of a
triangle by given: side and an altitude to it; three
sides; two sides and an angle between them. Use
System.Math.
13.
Write a program that enters file name along with its
full file path (e.g. C:\WINDOWS\win.ini), reads its
contents and prints it on the console. Find in MSDN
how to use System.IO.File.ReadAllText(…). Be
sure to catch all possible exceptions and print userfriendly error messages.
9
C# Language Overview (4)
14.
Write a program that downloads a file from Internet
(e.g. http://www.devbg.org/img/Logo-BASD.jpg)
and stores it the current directory. Find in Google
how to download files in C#. Be sure to catch all
exceptions and to free any used resources.
15.
Write a program that reads a string, reverses it and
prints it on the console. Example: "sample" 
"elpmas".
16.
Write a program that reads from a text file a list of
strings, sorts them and prints them on the console
in alphabetical order.
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C# Language Overview (5)
17. Write a program that finds how many times a
substring is contained in a given text (perform case
insensitive search).
Example: The target substring is "in". The text is as
follows:
We are living in an yellow submarine. We don't
have anything else. Inside the submarine is very
tight. So we are drinking all the day. We will
move out of it in 5 days.
The result is: 9.
11
C# Language Overview (6)
18.
Write a program that parses an URL address given
in the format:
[protocol]://[server]/[resource]
and extracts from it the [protocol], [server]
and [resource] elements. For example from the
URL http://www.devbg.org/forum/index.php
the following information should be extracted:
[protocol] = "http"
[server] = "www.devbg.org"
[resource] = "/forum/index.php"
12
C# Language Overview (7)
19.
Write a program that finds in given array of integers
(all belonging to the range [0..1000]) how many
times each of them occurs.
Example: array = {3, 4, 4, 2, 3, 3, 4, 3, 2}
2  2 times
3  4 times
4  3 times
20.
Write a program that reads a text file and finds all
words used in it and how many times each word
occurs. Assume that words differing in character
casing only are the same.
13
Object-Oriented
Programming in C#
OOP in C#
1.
Define a class Human with first name and last name.
Define new class Student which is derived from
Human and has new field – grade. Define class
Worker derived from Human with new field
weekSalary and work-hours per day and method
MoneyPerHour() that returns money earned by
hour by the worker. Define the proper constructors
and properties for this hierarchy. Initialize an array
of 10 students and sort them by grade in ascending
order. Initialize an array of 10 workers and sort them
by money per hour in descending order.
15
OOP in C# (2)
2.
Define abstract class Shape with only one virtual
method CalculateSurface() and fields width and
height. Define two new classes Triangle and
Rectangle that implement the virtual method
and return the surface of the figure (height*width for
rectangle and height*width/2 for triangle). Define
class Circle and suitable constructor so that on
initialization height must be kept equal to width
and implement the CalculateSurface() method.
Write a program that tests the behavior of the
CalculateSurface() method for different shapes
(Circle, Rectangle, Triangle) stored in an array.
16
OOP in C# (3)
3.
Create a hierarchy Dog, Frog, Cat, Kitten, Tomcat
and define suitable constructors and methods
according to the following rules: all of this are
Animals. Kittens and tomcats are cats. All animals
are described by age, name and sex. Kittens can be
only female and tomcats can be only male. Each
animal produce a sound. Create arrays of different
kinds of animals and calculate the average age of
each kind of animal using static methods. Create
static method in the animal class that identifies the
animal by its sound.
17
Lambda Expressions,
Extension Methods and LINQ
LINQ
1.
Create a class student with properties FirstName,
LastName, FN, Tel, Email, Marks (a List<int>),
GroupNumber. Create a List<Student> with
sample students. Select only the students that are
from group number 2. Use LINQ query. Order the
students by FirstName.
2.
Implement the previous using the same query
expressed with extension methods.
3.
Extract all students that have email in abv.bg. Use
string methods and LINQ.
4.
Extract all students having phones in Sofia (staring
with 02). Use LINQ and regular expressions.
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LINQ (2)
5.
Select all students that have at least one mark
Excellent (6) into a new anonymous class that has
properties – FullName and Marks. Use LINQ.
6.
Write down a similar program that extracts the
students with exactly two marks "2". Use extension
methods.
7.
Extract all Marks of the students that enrolled in
2006. (The students from 2006 have 06 as their 5-th
and 6-th digit in the FN).
8.
Create a class Group with properties GroupNumber
and DepartmentName. Introduce a property Group
in the Student class. Extract all students from
"Mathematics" department. Use the Join operator.
20
LINQ (3)
9.
Write a program to return the string with maximum
length from an array of strings. Use LINQ.
10.
Create a program that extracts all students grouped
by GroupName and then prints them to the console.
Use LINQ.
11.
Rewrite the previous using extension methods.
21
Submission Instructions
and Deadline
Submission Instructions
 Homework solutions
should be submitted at
the following Web site:
 http://nakov.devbg.org/schoolacademy-uploads/
 Solutions should be packed in a single ZIP or
RAR archive with a following structure
 IT-Test – directory for the IT test
 CSharp – directory for the C# solutions
 OOP – directory for the OOP solutions
 LINQ – directory for the LINQ solutions
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Further Instructions
 The deadline for the homework is:
 A week before the next training session
 Everybody is free to use help from friends,
teachers or Internet
 Submission of the same work by different
authors may result in a disqualification
 Ask your questions in the Telerik School
Academy official discussion group:
 http://groups.google.com/group/it-olymp
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Homework Assignments
Questions?
http://schoolacademy.telerik.com