Namespaces

1
Chapter 2
2
Chapter 2

• Namespaces
• Input and Output
• List of some classes in System, Math etc
• Compile and execute sequence

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Typing

• C is a strongly typed language
• Most formal languages are (C, Cobol, Java)
• Cannot mix numbers and characters
• Must know how big number will get

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Data Types

• Short (16 bit integer)
• Char (16 bit character)
• Float (32 bit floating point number)
• Boolean

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Helpful Table
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More on Data Types

• Numeric
• Integer (short, long, byte)
• Floating point (for decimal fractions)
• Decimal (with M suffix for money) 96 bits
• Double (includes decimal places)
• Character or String
• Any character that has to appear
• Boolean
• Represents logical values (TRUE OR FALSE)

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Numeric

• Integer
• Short(16) , long (32 bits), or byte (8bits)
• Literals when you use a value in the program
• Double (the default type)
• Up to 15 decimal digits
• Decimal
• Up to 28 digits
• Floating Point
• Used to describe numbers with decimals
• Use double to ensure full representation

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Character

• Char
• One character within single quotes (x)
• String
• String
• Many characters (a sentence)

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Boolean

• Bool data stores logical result (true or false)

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Conversion

• Sometimes programmer needs special variable
• Two types in C Implicit and Explicit
• Compiler protects user from unsafe choice
• Casting converts inline float pi(float) 3.14
• Default is double for Fl Pt literals
• Casting overrides the double and allows cast

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Program Style

• We listed some // comments earlier
• We also should have 4 sections in every program
• // declare section (where you assign variables
  etc)
• // input section (accept user input)
• // computations (where you do calculations)
• // display results
• IN THAT ORDER

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• using System
• namespace WTprog1
• // wt
• // program 1
• // due date" 1/31/05
• class Class1
• static void Main(string args)
• // declare section
• // input section
• // computation section
• // display section
• // end Main
• //end class
• // end namespace

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Variables

• To assign a value to an integer
• int age
• age 5
• int tells the compiler that an integer follows
• age is the case-sensitive variable name
• 5 is the value that will be stored in age
• If you had a statement to display the value,
• Console.WriteLine(age is age)
• Console.WriteLine(Age is 0, age)

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Variables Contd

• To assign a character value to a variable
• char name d
• Notice the single quotes?
• In C each character occupies 16 bits, so that
  even Japanese etc can fit
• You use string to input a whole name
• nameSmith

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Printing

• Your program
• string name jones
• string major IS
• string yr 02
• Console.WriteLine(My name is name)
• Console.WriteLine(Major mj year yr)
• Console.WriteLine(Major 0, Year 1,
  major, yr

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Variables

• To get the computer to read data
• string name Console.ReadLine()
• Then you can use name as needed