Lesson 4 Basic Programming Constructs.pptx

Grade 10 Lesson 1 Quarter 4

1. Basic Programming Constructs

2. Variable Programmer-defined word that holds the value of the user. Portion of the memory to store a determined value.

3. Rules in Declaring variables It must begin with a letter or underscore (_), then followed by a letter, digit, or underscore. It must not include blanks. It must not be the keywords, which are reserved words by the language. It must not be given a name with the same name as other functions.

4. Constant Expression with a fixed value that cannot be changed at runtime. To declare a constant in C#, the const keyword is used. To define a constant, this syntax should be followed: Const < data_type > < constant_name > = value;

5. Literals Values within the source code of a program. Examples a= 5; 5 in this piece of code is a literal constant. Literal Constant can be integer numerals, floating-pointing numerals, characters, strings , or Boolean values.

6. Integer literals Constant and are also called decimal numerals. For example 235 612 18 29

7. Floating-point literal Numbers with decimals, fractions, and /or exponents. For Example: 3.14159 // 3.14159 6.02e23 // 6.02 x 10

8. Character and String Non-numeric constant like ‘z’ – character ‘j’ – character ‘a’ – character “ jasmin ” – string “Hello World” - string

9. Data type Variable allocated in the computer’s memory. Variable should be identified based on the type of data it can hold. Data types categorized as value types and reference type.

10. Value type Holds data within its own memory location

11. Reference type Contains a pointer to another memory location that holds the data. int a = 42; char ch = ‘A’; bool result = true; Value types object obj = 42; string str = “Hello”; byte[] bytes = {1,2,3}; - Reference type

12. Characteristics of a Data type Name – value type Size – how much memory they use Default value – the initial value

13. Type Description Range Represent bool Represent True or false True or False Boolean Value sbyte Signed byte -128 to 127 8-bit signed integer type byte Unsigned byte 0 to 255 8-bit unsigned integer short Short integer -32,768 to 32,767 16-bit signed integer type ushort Unsigned short integer 0 to 65,535 16-bit unsigned integer type int Integer -2,147,483,648 to 2,147,483,647 32-bit signed integer type uint Unsigned integer 0 to 4,294,967,295 32-bit unsigned integer type long 64-bit signed integer type -9,223,372,036,854,775,808 to 9,223,372,036,854,775,808 64-bit signed integer type ulong Unsigned long integer 0 to 18,446,744,073,709,551,615 64-bit unsigned integer type decimal Use this data type for currency value (-7.9 x 10 28 to 7.9 x 10 28 ) /10 to 28 128-bit precise decimal values with 28-29 significant digits

14. Type Description Range Represent float Floating point number -3.4 x 10 38 to +3.4 x 10 38 32-bit single -precision floating point type Double Double floating point (+/-) 5.0 x 10 -324 to (+/-)1.7 x 10 308 64-bit double-precision floating point type Char Unicode character Any valid character 16-bit Unicode character

15. C# supports unsigned data types for short, long and int which uses letter ‘u’ + data type for identification Unsigned used to exclude the negative sign while signed data types are value can have a negative number Example int -247 and Uint 247

16. Reference types Reference type Description Size Object Base type of all other types 8+ bytes String Character array 20+bytes

17. Reference types A variable is declared like this: <data type><variable>; Example: string name; int a,b,c ; Variable can have an initial value by adding a value to it during its declaration. It is declared as: <Data type > <variable name> = value; Example int a=5; double B= 2.9; double pi= 3.1416

18. //Declare and initialize some variables byte centuries = 20; ushort years= 2000; decimal decimalPI = 3.141592653589793238m; bool isEmpty = true; char ch = ‘a’; string firstName =“John”; ch = (char)5; char secondChar ; // Here we use an already initialized variable and reassign it secondchar = ch ;

19. What is a Console

20. Console A window, which users can interact with in a system program. Interaction can be by text input from standard input (keyboard), text display standard output (monitor), or simply input-output operations. System.Console class has different properties and methods which are used to read and display text on the console as well as its formatting.

21. What are C# Input/Output Statement

22. I/O statement Used for user and computer interaction. It uses the standard input stream Console. Print information on the standard output stream Console.Out , and can signal for problem situations in the standard error stream Console.Error . Example: Console.Out.WriteLine (“Hello World”); Output: Hello World

23. Console.Write / WriteLine Method that can print all basic types (string, numeric, and primitive type). Console.Write writes the text and places the cursor after the last character while the Console. WriteLine writes the text and places the cursor to the next line.

24. Example // Print String Console.WriteLine (“Hello World ); //Print int Console.WriteLine (5); // Print Double Console.WriteLine (3.141512412412)

25. Output Hello World 5 3.141512412412

26. String Concatenation Combining two strings and returns as a result of a new string. C# uses ‘+’ operator to concatenate two strings. For example: string age = “twenty-six”; String text = “ He is” + age + “years old”; Console.WriteLine (text); Output: He is twenty-six years old.

27. Mixed String Concatenation Concatenation can be done alternately with a variable. Composed of an output text followed by a variable then another output text. Example int age = 26; String text = “He is “ + age + “years old. “ ; Console.WriteLine (text);

28. Console.Read / ReadLine ()

29. More Example