C

1
C Language

• BCS 2203
• Web Application Development
• Nor Azhar Bin Ahmad

2
Overview

• C Basics
• Variables
• Datatype Conversion
• Control Structures
• Methods

3
C Basics

• Many similarities to PHP
• Case sensitive
• Curly brackets
• End statements with semi-colons
• double equal signs to test equality
• if (i 3)
• Comments
• // single line
• / Multi-line
• comment like this /

4
C Basics

• Classes in class library all start with upper
  case
• Properties methods too
• Response.Write()
• Request.Querystring()
• Statements are lower case
• if (
• return
• foreach (
• false

5
Variables

• Declaring Variables
• .NET languages are strongly typed
• PHP ASP loosely typed
• Strongly typed
• A variable accepts only one data type
• Type is explicitly declared when variable is
  declared
• Advantage
• Less error prone
• Compiler more likely to catch programming errors
• Disadvantage
• Many explicit data type conversions

6
Variables

• Declaring Variables
• string strName
• int intAge
• Declare assign value
• string strName Joe
• int intAge 6

7
Variables

• Commonly Used C Data Types

8
Variables

• Variables are objects
• Have properties methods
• Defined in System namespace
• String documentation

9
Variables

• Example
• C declaration
• string Fname joseph
• Fname is string object
• Use ToUpper method
• Fname Fname.ToUpper()

10
Concatenation

• Concatenate strings with
• string Name lastName , firstName
• End of statement
• Semicolen

11
Datatype Conversion

• C strongly typed language
• Data types must be explicitly converted
• Several ways to re-cast data types
• Convert Class
• most robust
• easy to use

12
Datatype Conversion

• Convert Class
• decimal TaxRate Convert.ToDecimal(8.15)

13
Datatype Conversion

• Server controls all return data type string
• double TaxRate tbTaxRate.Text
• Compiler Error Message CS0029 Cannot implicitly
  convert type 'string' to 'double'
• Re-cast to type double
• Double TaxRate Convert.ToDouble(tbTax.Text)
• Example CSharpDataType.aspx (source)

14
Outline

• C Basics
• Variables
• Datatype Conversion
• Control Structures
• Methods

15
Control Structures

• Syntax similar to PHP, Java, C, C,
• Curley brackets for statement blocks
• if (condition)
• //Statement block
• else
• //statement block

16
Control Structures

• Curley brackets not needed for single
  statements
• if (condition)
• statement 1
• else
• statement 2

17
Control Structures

• Testing conditions
• Equality
• double equal sign
• if (age 3)
• Inequality
• if (age gt 3)
• Negate
• if (age ! 3)
• if (! Page.IsPostBack)
• AND / OR
• and
• or

18
Control Structures

• Control Statements
• if
• for
• foreach
• while

19
Control Structures

• 1. if else
• if (condition)
• //do something
• else if (condition)
• //do something
• else
• //do something else

20
Control Structures

• 2. for statement
• increments a counter variable
• may declare within statement
• for (int i 0 i lt 10 i)
• lblMessage.Text i "ltbrgt"

21
Control Structures

• 3. foreach loop
• iterate through collections
• arrays, controls, cookies, etc.
• int intArray 3, 5, 7, 9, 11
• foreach (int item in intArray)
• Response.Write("Age" item "ltbrgt")

22
Control Structures

• 4. while loop
• int i 0
• while (i lt 5)
• i 1
• Response.Write("i " i "ltbrgt")

23
Overview

• C Basics
• Variables
• Datatype Conversion
• Control Structures
• Methods

24
Methods

• Also known as
• Subroutines in VB
• Functions in PHP
• Chunks of code that do something useful
• Pass parameters in, return a result
• int myDoubler(int intValue)
• return intValue 2

25
Methods

• return void if no value returned
• void empty
• void page_load()
• Response.Write(Hi Mom)

26
Example

• FontPickerCSharp.aspx
• Output
• Source

27
Summary

• C syntax follows PHP (C-like) conventions
• Case sensitive
• Semi-colons at end of statements
• Curley brackets define blocks
• Functions called Methods
• Explicitly convert data types
• No changes to class library
• Classes start with upper case
• Pick up syntax quickly
• Visual Studio big help