Bài giảng lập trình c 2010 chương 1 1 đh công nghệ đồng nai

DONG NAI UNIVERSITY OF TECHNOLOGY


DONG NAI UNIVERSITY OF TECHNOLOGY

Working with Variables,
Operators and Expressions


DONG NAI UNIVERSITY OF TECHNOLOGY

1

Statements

2

-Comments

3
Identifiers

4
Primitive Data Types

5

Variables

Arithmetic
Operators

6
Incrementing &
Decrementing Variables

7

Implicitly Typed Local
Variables


DONG NAI UNIVERSITY OF TECHNOLOGY

-A Statement is a command that performs an action,
you must add “;” the end of command
-Ex: Console.Write(“Hello C# ”);
1

Statements
-Comments
-Comments use to explain for your Coding
How to write comments???
See next slide…


DONG NAI UNIVERSITY OF TECHNOLOGY

//Comment 1

/// <summary>

///Write Comment 4

/*

/// </summary>

*Comment 2

/// </param>

*/

/// </param>
private void func1(int a,float b)

/*Comment 3*/


DONG NAI UNIVERSITY OF TECHNOLOGY

Identifiers are names use to identify the elements in
program, ex: namespace, class, method…
Syntax Rules:

2
Identifiers

-Only use letter, digit, underscore
-An identifier must start with a letter or an underscore
-C# is a case –sensitive : nTest and ntest is different

identifier


DONG NAI UNIVERSITY OF TECHNOLOGY

Identifying Keywords
abstract

do

in

protected

as

double

int

base

else

interface

readonly

bool

enum

internal

ref

break

event

is

return

ulong

byte

explicit

lock

sbyte

unchecked

case

extern

long

sealed

unsafe

catch

false

namespace

short

ushort

char

finally

new

sizeof

using

checked

fixed

public

true

null

class

float

object

const

for

operator
foreach

out

decimal

goto

override

if

params

implicit

private

dynamic

join

set

from

let

value

get

orderby

group

partial

where

into

select

yield

var

virtual

void
string

volatile

struct

while
switch

this

delegate

typeof
uint

stackalloc
static

continue

default

try

throw


DONG NAI UNIVERSITY OF TECHNOLOGY

- A variable is storage location that holds a value. It as a
box in the Computer’s memory holding temporary
information.
-To easy coding:
3

+Don’t start an identifier with underscore
Variables

+Don’t different only by case ( nTest and ntest)
+Start name with lower case
+….


DONG NAI UNIVERSITY OF TECHNOLOGY

How to declare variables?

Data_type NameVariable;
int nNumberOfElement;
string strFullName;
float fValue=0,fResult;

DONG NAI UNIVERSITY OF TECHNOLOGY

Primitive Data Types

4

Data Type

Description

Size(bits)

int

Whole numbers

32

Range
31
31
–2 through 2 – 1

64

63
63
–2 through 2 – 1

long lSize;

32

45
38
±1.5 × 10 through ±3.4 × 10

float fDelta;

64

±5.0 × 10

long

float

Whole numbers
(bigger range)
Floating-point numbers

Double-precision (more
double

accurate) floating-point

−324

through ±1.7 × 10

Example
int nSize;

308

double dDelta;

numbers

decimal

Monetary values

128

28 significant figures

decimal decKe;

string

Sequence of characters

16 bits per character

Not applicable

string strName;

char

Single character

16

0 through 2

bool

Boolean

8

True or false

16

–1

char chrAns;
bool bRet;


DONG NAI UNIVERSITY OF TECHNOLOGY

You should initialize value for variable
int nSize=0;
String strName=“”;

DONG NAI UNIVERSITY OF TECHNOLOGY

5

Arithmetic
Operators

+

-

*

/

%

()

int nPlusTwoNumber=113 + 114
The + is the operator
113 and 114 are the operands


DONG NAI UNIVERSITY OF TECHNOLOGY

Not all operators are applicable to all data
types
Example:

You will get compiler error with the
statements:
Console.WriteLine(“Tý” - “Tèo”);


DONG NAI UNIVERSITY OF TECHNOLOGY

How to convert from String to Number Format ?
int nValue=System.Int32.Parse("113");
double dValue = System.Double.Parse("3.5");

Datatype vName=System.DataTypeObject.Parse(“string”);


DONG NAI UNIVERSITY OF TECHNOLOGY

X++

++X

Postfix increment

Prefix increment

X--

--X

Postfix decrement

Prefix decrement

6
Incrementing &
Decrementing Variables


DONG NAI UNIVERSITY OF TECHNOLOGY

7

Implicitly Typed Local
Variables

var number1=1;
var strAny=“tèo”;

var sAny;
Error: Implicitly-typed local variables must be initialized


DONG NAI UNIVERSITY OF TECHNOLOGY

END