1. Visual Programming
Lecture 3

2. Introduction to C# Applications
Console.WriteLine() method
Comments
Single line
Multi line
Keywords
Contextual Keywords
C# is case sensitive language
Display line numbers in editor
Use Tools > Options…
Under “Text Editor > All Languages” select “Line numbers”

3. Continued… Changing the name of application file IntelliSense feature
Use Properties window
IntelliSense feature
Saving the application
Compiling and Running the Application
Compiler may create .exe, .dll or other files called assemblies
These assemblies contain MSIL code
Console.ReadKey() method
Role of Ctrl+F5 command
Discussion on “Error List” window
If not visible use “View > Error List”

4. Continued… Parameter info window Error List Window
Shows the description of the syntax error in the code (red underlined)
Difference between Console.Write() and Console.WriteLine() method
Displaying multiple lines with a single statement
Console.WriteLine(“Welcome\nto\nC#\nProgramming”);
Escape sequences
\n, \t, \\, \”
Displaying formatted text
Console.WriteLine(“{0}\n{1}”,”Welcome to”, “C# Programming!”);

5. Another C# Application – Adding Integers
Console.Write("Enter first integer: ");
number1 = Console.ReadLine();
Problems with this code
Solution
number1 = Convert.ToInt32(Console.ReadLine());

6. Complete Program int number1; int number2; int sum;
Console.Write("Enter first integer: ");
number1 = Convert.ToInt32(Console.ReadLine());
Console.Write("Enter second integer: ");
number2 = Convert.ToInt32(Console.ReadLine());
sum = number1 + number2;
Console.WriteLine("Sum is {0}", sum);

7. Miscellaneous Topics Data types
Int, long, char, string, float, double, decimal, bool
Console.ReadKey() and Console.ReadLine() methods
Arithmetic operators
+, -, *, /, %, ++ (prefix and postfix), -- (prefix and postfix)
Relational operators
==, !=, >, <, >=, <=
Logical operators
&&, &, ||, |, !
Compound Assignment Operators
*=, +=, -=, /=, %=, &=, |=, ^=

8. Exercise
Write a program which will ask user to enter 3 double values and then show their product.