1 Mục lục 1 2 Làm quen với visual basic 0 9



tải về 1.69 Mb.
trang7/39
Chuyển đổi dữ liệu09.10.2016
Kích1.69 Mb.
#32631
1   2   3   4   5   6   7   8   9   10   ...   39

4.3Các điều khiển M ới


  • Điều khiển ADO data

  • Điều khiển Coolbar

  • Điều khiển D ata grid

  • Điều khiển Datalist, DataCombo

  • Điều khiển DataRepeater

  • Điều khiển DataTimePicker

  • Điều khiển Flat Scollbar

  • Điều khiển Hierarchical FlexGrid

  • Điều khiển ImageComBo

  • Điều khiển Month View

5Nhập môn lập trình


Các điều khiển trên biểu mẫu chỉ là một phần nhỏ của quá trình lập trình phát triển ứng dụng, nhằm tạo ra giao diện cho ứng dụng. Sau đó, bạn cần viết chương trình để ứng dụng hoạt động. Do đó, chương này sẽ đi sâu vào phần công việc chính của Visual Basic, viết chương trình.

Visual Basic là ngôn ngữ lập trình dựa trên đối tượng. Nếu bạn là người mới học, chương này sẽ giới thiệu các khối thiết kế cơ bản để xây dựng chương trình. Khi đã hiểu được các khái niệm cơ bản, bạn có thể tạo ra các ứng dụng rất mạnh bằng Visual Basic.


5.1Chuẩn lập trình (Coding convention)

5.1.1Coding conventions


Object Naming Conventions

Object name has 2 parts: prefix and description.

The prefix that makes it easy to identify the type of object, the description mentions name of objects.

- Conventions of description part are:

+ In English.

+ Can contain many words, each word is contiguous to others (No hyphen).

+ No acronym except listed in table Acronyms (see 4. Acronym).

+ Capitalize the first letter of each word.

(Note: These conventions will be applied to all of name types mentioned after in this document)

- Prefix conventions for some of the objects supported by Visual Basic are listed below (Sorted by control name):




Control type

Prefix

Example

3D Panel

Pnl

pnlGroup

ADO Data

Ado

adoBiblio

Animated button

Ani

aniMailBox

Check box

Chk

chkReadOnly

Combo box, drop-down list box

Cbo

cboEnglish

Command button

Cmd

cmdExit

Common dialog

dlg

dlgFileOpen

Communications

com

comFax

Control (used within procedures when the specific type is unknown)

ctr

ctrCurrent

Data

dat

datBiblio

Data-bound combo box

dbcbo

dbcboLanguage

Data-bound grid

dbgrd

dbgrdQueryResult

Data-bound list box

dblst

dblstJobType

Data combo

dbc

dbcAuthor

Data grid

dgd

dgdTitles

Data list

dbl

dblPublisher

Data repeater

drp

drpLocation

Date picker

dtp

dtpPublished

Directory list box

dir

dirSource

Drive list box

drv

drvTarget

File list box

fil

filSource

Flat scroll bar

fsb

fsbMove

Form

frm

frmEntry

Frame

fra

fraLanguage

Gauge

gau

gauStatus

Graph

gra

graRevenue

Grid

grd

grdPrices

Hierarchical flexgrid

flex

flexOrders

Horizontal scroll bar

hsb

hsbVolume

Image

img

imgIcon

Image combo

imgcbo

imgcboProduct

ImageList

ils

ilsAllIcons

Label

lbl

lblHelpMessage

Lightweight check box

lwchk

lwchkArchive

Lightweight combo box

lwcbo

lwcboGerman

Lightweight command button

lwcmd

lwcmdRemove

Lightweight frame

lwfra

lwfraSaveOptions

Lightweight horizontal scroll bar

lwhsb

lwhsbVolume

Lightweight list box

lwlst

lwlstCostCenters

Lightweight option button

lwopt

lwoptIncomeLevel

Lightweight text box

lwtxt

lwoptStreet

Lightweight vertical scroll bar

lwvsb

lwvsbYear

Line

lin

linVertical

List box

lst

lstPolicyCodes

ListView

lvw

lvwHeadings

MAPI message

mpm

mpmSentMessage

MAPI session

mps

mpsSession

MCI

mci

mciVideo

Menu

mnu

mnuFileOpen

Month view

mvw

mvwPeriod

MS Chart

ch

chSalesbyRegion

MS Flex grid

mfg

mfgClients

MS Tab

mst

mstFirst

OLE container

ole

oleWorksheet

Option button

opt

optGender

Picture box

pic

picVGA

Picture clip

clp

clpToolbar

ProgressBar

prg

prgLoadFile

Remote Data

rd

rdTitles

RichTextBox

rtf

rtfReport

Shape

shp

shpCircle

Slider

sld

sldScale

Spin

spn

spnPages

StatusBar

sta

staDateTime

SysInfo

sys

sysMonitor

TabStrip

tab

tabOptions

Text box

txt

txtLastName

Timer

tmr

tmrAlarm

Toolbar

tlb

tlbActions

TreeView

tre

treOrganization

UpDown

upd

updDirection

Vertical scroll bar

vsb

vsbRate


Prefix conventions for menus
Menu control prefixes will be extended beyond the initial "mnu" label by adding an additional prefix for each level of nesting, with the final menu caption at the end of the name string. The following table lists some examples.

Menu caption sequence

Menu handler name

File Open

mnuFileOpen

File Send Email

mnuFileSendEmail

File Send Fax

mnuFileSendFax

Format Character

mnuFormatCharacter

Help Contents

mnuHelpContents

Variable naming conventions

Variable name must describe data type, scope and identifier of a variable.



Variable data types

Data type

Prefix

Example

Boolean

bln




Byte

byt




Currency

cur




Date (Time)

dtm




Double

dbl




Error

err




Integer

int




Long

lng




Object

obj




Single

sng




String

str




User-defined type

udt




Variant

vnt





Variable scope prefixes

Scope

Prefix

Example

Note

Global

G

gstrUserName

This variable is global and string type

Module-level

M

mblnCalcInProgress

This variable is module and boolean type

Local to procedure

None

dblVelocity

This variable is local and double type


Constants

The constant names will be UPPER_CASE with underscores (_) between words. For example:



Example

Note

USER_LIST_MAX




NEW_LINE




Prefixes for ActiveX Data Objects (ADO)

Use the following prefixes to indicate ActiveX Data Objects.



ADO object

Prefix

Example

Command

Cm

cmTitles

Connection

Cn

cnTitles

Field

Fld

fldName

Field Collection

flds

fldsTitles

Parameter

prm

prmTitleName

Parameter Collection

prms

prmsNames

Recordset

Rs

rsTitles


Structured Coding Conventions
In addition to naming conventions, structured coding conventions, such as code commenting and consistent indenting, can greatly improve code readability.

Code Commenting Conventions

All procedures and functions should begin with a brief comment describing the functional characteristics of the procedure (what it does). Input, output patameters passed to a procedure should be described. Function return values and global variables that are changed by the procedure must also be described at the beginning of each procedure.



Section heading

Comment description

Purpose

What the procedure does (not how).

Inputs

Describe roles of input parameters

Outputs

Describe roles of output parameters

Returns

Explanation of the values returned by functions.

Author

Author of module

Remember the following points:

  • Every important variable declaration should include an inline comment describing the use of the variable being declared.

  • Variables, controls, and procedures should be named clearly enough that inline commenting is only needed for complex implementation details.

  • At the start of the.bas module that contains the project's Visual Basic generic constant declarations, we should include an overview that describes the application, enumerating primary data objects, procedures, algorithms, dialogs, databases, and system dependencies. Sometimes a piece of pseudocode describing the algorithm can be helpful.

Formatting Your Code

Here are a few pointers:



  • Standard, tab-based, nested blocks should be indented four spaces (as the Visual Basic default).



  • The functional overview comment of a procedure should be indented one space. The highest level statements that follow the overview comment should be indented one tab, with each nested block indented an additional tab. For example:


'*****************************************************

' Purpose: Locates the first occurrence of a

' specified user in the UserList array.

' Inputs:

' strUserList(): the list of users to be searched.

' strTargetUser: the name of the user to search for.

' Returns: The index of the first occurrence of the

' rsTargetUser in the rasUserList array.

' If target user is not found, return -1.

'*****************************************************
Function FindUser (strUserList() As String, strTargetUser As _

String)As Integer

Dim inti As Integer ' Loop counter.

Dim blnFound As Integer ' Target found flag.

intFindUser = -1

inti = 0

While inti <= Ubound(strUserList) and Not blnFound

If strUserList(inti) = strTargetUser Then

blnFound = True

intFindUser = inti

End If

Wend

End Function

Grouping Constants

Visual Basic generic constants will be grouped in a single module to separate them from application-specific declarations.



& and + Operators

Always use the & operator when linking strings and the + operator when working with numerical values. Using the + operator to concatenate may cause problems when operating on two variants. For example:


vntVar1 = "10.01"

vntVar2 = 11

vntResult = vntVar1 + vntVar2 'vntResult = 21.01

vntResult = vntVar1 & vntVar2 'vntResult = 10.0111

Creating Strings for MsgBox, InputBox, and SQL Queries

When creating a long string, use the underscore line-continuation character to create multiple lines of code so that you can read or debug the string easily. This technique is particularly useful when displaying a message box (MsgBox) or input box (InputBox) or when creating an SQL string. For example:


Dim Msg As String

Msg = "This is a paragraph that will be " _

& "in a message box. The text is" _

& " broken into several lines of code" _

& " in the source code, making it easier" _

& " for the programmer to read and debug."

MsgBox Msg
Dim QRY As String

QRY = "SELECT *" _

& " FROM Titles" _

& " WHERE [Year Published] > 1988"

TitlesQry.SQL = QRY

Other conventions

Error trapping in development progress must follow these rules:

- Cascading error trapping. That mean all called functions will return system error codes, and showing message box will be implemented at the most exterior function/procedure.

- All system message will be located in resource file.

- Showing message boxes are implemented by pass parameters to a showing message global function.

- Error code contains 3 number.

- Versioning all modules: form module, code module...

- Display solution: 800x600 pixels

- Font size setting: Large font

- All of file name (*.vbp, *.frm, *.bas...) must less than 3 characters.

- Error code = 0 is OK.

- Error code < 0 is error.

- Error code >0 is warning.

- Function names should begin with a verb, such as InitNameArray or CloseDialog.


5.1.2Form design standard


Common conventions in form design

Items

Conventions

Note

Interface

In Vietnamese




Font name

MS Sans serif

Default

Font size

Default




Font color

Black

Default

Font style

Normal

Default

Distance between command buttons

100 Points




Command buttons alignment

Right




Label alignment

Left




All labels in a form must be collected in an array







All command buttons in a form must have same width







Caption of OK button

Chấp nhận




Caption of Cancel button

Thoát




Caption of Help button

Hướng dẫn




Caption of Add button

Thêm mới




Caption of Delete button

X




Caption of Edit button

Sửa




Caption of Close button

Đóng




Caption of Save button

Ghi




Order of buttons in from (Left to right):

Thªm míi-Ghi-Söa-Xo¸-ChÊp nhËn-Tho¸t-H­íng dÉn









Default button

Chấp nhận




Cancel button

Đóng




Sample:


Form controls appearance conventions

Control

Property

Value

Note

Check box













All colors

Default




Combo box, drop-down list box













Height

315







All colors

Default
















Command button













Height

375 Points







Back color

Button face

VB Default

Form













Border style

Fixed length







Back color

Button face

VB Default




Startup position

CenterScreen




Label













Back color

Button face

VB Default

Vervical scroll bar













Width

260 Points




Horizontal scroll bar













Height

260 Points




Option button













Height

255 Points




Text box













Height

285 Points







All color

Default



5.1.3Report design standard (for Crystal Report)


Common conventions in report design

Items

Conventions

Note

Above of each total row must be a line, called Grouping line







Report boder

Only title row is bordered




Colour of all objects in report (line, character...)

Black





Report objects appearance conventions

Object

Property

Setting

Note

Report title













Font name

.VnArialH







Font style

Bold







Justify

Paper center







Space between report title and collumn heading

50 Points

Should be reviewed

Colunm heading













Font name

.VnArialNarrow







Font style

Bold







Font size

10







Justify

Column left







Before row spacing

6 Points







After row spacing

6 Points
















Report body (data)













Font name

.VnArialNarrow







Font style

Bold







Font size

9







Justify

Depend on column data type (Number: right, string: right, date: center)







Row spacing

0




Total row













Font name

.VnArialNarrow







Font style

Bold







Font size

9







Justify

Right







Position

Under data block that summarized




Grouping line













Width

1 Point




Report boder













Width

1 Point







Boder column title only







Page number













Font name

.VnArial







Font size

9







Font style

Normal







Position

Right, bottom of page (Report footer)







Style

Page/Total page




Left sub title













Font name

.VnArial







Font size

10







Font style

Normal







Justify

Margin left




Right sub title













Font name

.VnArial







Font size

10







Font style

Normal



Sample:



Left subtitle

Report title

Right subtitle




Column heading 1

Column heading 2

Column heading 3

Column heading 4

Report body 1

Report body 2

Report body 3

Report body 4

Report body 1

Report body 2

Report body 3

Report body 4










Total row 4

Report body 1

Report body 2

Report body 3

Report body 4

Report body 1

Report body 2

Report body 3

Report body 4










Total row 4

(Page number) 1/5


5.1.4Database design standards


All of object names (include: table names, view names, field names...) in database must follow these conventions:

- In English.

- Can containts one or more words and no underscore between these words.

- No acronym except listed in table Acronyms bellow.

- The first letter of each word must be capitalized.



tải về 1.69 Mb.

Chia sẻ với bạn bè của bạn:
1   2   3   4   5   6   7   8   9   10   ...   39




Cơ sở dữ liệu được bảo vệ bởi bản quyền ©hocday.com 2024
được sử dụng cho việc quản lý

    Quê hương