Note :
The terms Pascal Casing and Camel Casing are used throughout
this document.
Pascal Casing - First character
of all words are Upper Case and other characters are lower case.
Example: BackColor
Camel Casing - First character of
all words, except the first word are Upper Case and other characters
are lower case.
Example: backColor
|
1.
Use Pascal casing for Class names
public class HelloWorld
{
...
}
2.
Use Pascal casing for Method names
void SayHello(string name)
{
...
}
3.
Use Camel casing for variables and method
parameters
int totalCount = 0;
void SayHello(string name)
{
string
fullMessage = "Hello " + name;
...
}
4.
Use the prefix “I” with Camel Casing for
interfaces ( Example: IEntity )
5.
Do not use Hungarian notation to name
variables.
In
earlier days most of the programmers liked it - having the data type as a
prefix for the variable name and using m_ as prefix for member variables. Eg:
string m_sName;
int nAge;
However,
in .NET coding standards, this is not recommended. Usage of data type and m_ to
represent member variables should not be used. All variables should use camel
casing.
Some programmers still prefer to use the
prefix m_ to represent member variables, since there is no other easy
way to identify a member variable.
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6.
Use Meaningful, descriptive words to name
variables. Do
not use abbreviations.
Good:
string address
int salary
Not Good:
string nam
string addr
int sal
7.
Do not use single character variable names
like i,
n, s etc.
Use names like index, temp
One
exception in this case would be variables used for iterations in loops:
for ( int i = 0; i < count; i++ )
{
...
}
If
the variable is used only as a counter for iteration and is not used anywhere
else in the loop, many people still like to use a single char variable (i)
instead of inventing a different suitable name.
8.
Do not use underscores (_) for local variable
names.
9.
All member variables must be prefixed with
underscore (_) so that they can be identified from other local variables.
10. Do not use
variable names that resemble keywords.
11. Prefix boolean
variables, properties and methods with “is” or similar
prefixes.
Ex: private bool
_isFinished
12. Namespace
names should follow the standard pattern
<company name>.<product
name>.<top level module>.<bottom level module>
13.
Use appropriate prefix for the UI elements so
that you can identify them from the rest of the variables.
There are 2 different
approaches recommended here.
a.
Use a common prefix ( ui_ ) for all UI
elements. This will help you group all of the UI elements together and easy to
access all of them from the intellisense.
b.
Use appropriate prefix for each of the ui
element. A brief list is given below. Since .NET has given several controls,
you may have to arrive at a complete list of standard prefixes for each of the
controls (including third party controls) you are using.
Control
|
Prefix
|
Label
|
lbl
|
TextBox
|
txt
|
DataGrid
|
dtg
|
Button
|
btn
|
ImageButton
|
imb
|
Hyperlink
|
hlk
|
DropDownList
|
ddl
|
ListBox
|
lst
|
DataList
|
dtl
|
Repeater
|
rep
|
Checkbox
|
chk
|
CheckBoxList
|
cbl
|
RadioButton
|
rdo
|
RadioButtonList
|
rbl
|
Image
|
img
|
Panel
|
pnl
|
PlaceHolder
|
phd
|
Table
|
tbl
|
Validators
|
val
|
14. File name
should match with class name.
For
example, for the class HelloWorld, the file name should be helloworld.cs (or,
helloworld.vb)
15. Use Pascal
Case for file names.
1.
Use TAB for indentation. Do not use SPACES. Define the Tab size as 4.
2.
Comments should be in the same level as the
code (use the same level of indentation).
Good:
// Format
a message and display
string
fullMessage = "Hello " + name;
DateTime
currentTime = DateTime.Now;
string
message = fullMessage + ", the time is : " +
currentTime.ToShortTimeString();
MessageBox.Show
( message );
Not Good:
// Format
a message and display
string fullMessage = "Hello " + name;
DateTime currentTime = DateTime.Now;
string
message = fullMessage + ", the time is : " +
currentTime.ToShortTimeString();
MessageBox.Show ( message );
3.
Curly braces ( {}
) should be in the same level as the code outside the braces.
4.
Use one blank line to separate logical groups
of code.
Good:
bool SayHello ( string name )
{
string fullMessage = "Hello
" + name;
DateTime currentTime =
DateTime.Now;
string message = fullMessage +
", the time is : " + currentTime.ToShortTimeString();
MessageBox.Show ( message );
if ( ... )
{
// Do something
// ...
return false;
}
return true;
}
Not
Good:
bool SayHello (string name)
{
string fullMessage = "Hello
" + name;
DateTime currentTime =
DateTime.Now;
string message = fullMessage +
", the time is : " + currentTime.ToShortTimeString();
MessageBox.Show ( message );
if ( ... )
{
// Do something
// ...
return false;
}
return true;
}
5.
There should be one and only one single blank
line between each method inside the class.
6.
The curly braces should be on a separate line
and not in the same line as if, for etc.
Good:
if ( ... )
{
// Do something
}
Not
Good:
if ( ... ) {
// Do something
}
7.
Use a single space before and after each
operator and brackets.
Good:
if ( showResult == true )
{
for ( int i = 0; i < 10;
i++ )
{
//
}
}
Not
Good:
if(showResult==true)
{
for(int i=
0;i<10;i++)
{
//
}
}
8.
Use #region to group related
pieces of code together. If you use proper grouping using #region, the page
should like this when all definitions are collapsed.
9.
Keep private member variables, properties and
methods in the top of the file and public members in the bottom.
1.
Avoid writing very long methods. A method
should typically have 1~25 lines of code. If a method has more than 25 lines of
code, you must consider re factoring into separate methods.
2.
Method name should tell what it does. Do not
use mis-leading names. If the method name is obvious, there is no need of
documentation explaining what the method does.
Good:
void SavePhoneNumber ( string phoneNumber
)
{
// Save the phone number.
}
Not
Good:
// This method will save the phone
number.
void SaveDetails ( string phoneNumber )
{
// Save the phone number.
}
3.
A method should do only 'one job'. Do not
combine more than one job in a single method, even if those jobs are very
small.
Good:
// Save the address.
SaveAddress ( address );
// Send an email to the supervisor to
inform that the address is updated.
SendEmail ( address, email );
void SaveAddress ( string address )
{
// Save the address.
// ...
}
void SendEmail ( string address, string
email )
{
// Send an email to inform the
supervisor that the address is changed.
// ...
}
Not
Good:
// Save address and send an email to the
supervisor to inform that
//
the address is updated.
SaveAddress ( address, email );
void SaveAddress ( string address, string
email )
{
// Job 1.
// Save the address.
// ...
// Job 2.
// Send an email to inform the
supervisor that the address is changed.
// ...
}
4.
Use the c# or VB.NET specific types (aliases),
rather than the types defined in System namespace.
int age;
(not Int16)
string name; (not String)
object contactInfo; (not Object)
Some developers prefer to use types in Common Type System than language
specific aliases.
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5.
Always watch for unexpected values. For
example, if you are using a parameter with 2 possible values, never assume that
if one is not matching then the only possibility is the other value.
Good:
If (
memberType == eMemberTypes.Registered )
{
// Registered user… do something…
}
else if (
memberType == eMemberTypes.Guest )
{
// Guest user... do something…
}
else
{
//
Un expected user type. Throw an exception
throw
new Exception (“Un expected value “ + memberType.ToString() + “’.”)
// If we introduce a new user type in
future, we can easily find
// the problem here.
}
Not
Good:
If (
memberType == eMemberTypes.Registered )
{
// Registered user… do something…
}
else
{
// Guest user... do something…
// If we
introduce another user type in future, this code will
// fail
and will not be noticed.
}
6.
Do not hardcode numbers. Use constants
instead.
Declare constant in the top of the file and use it in your code.
However, using
constants are also not recommended. You should use the constants in the config
file or database so that you can change it later. Declare them as constants
only if you are sure this value will never need to be changed.
7.
Do not hardcode strings. Use resource files.
8.
Convert strings to lowercase or upper case
before comparing. This will ensure the string will match even if the string
being compared has a different case.
if ( name.ToLower() == “john” )
{
//…
}
9.
Use String.Empty instead of “”
Good:
If ( name
== String.Empty )
{
// do something
}
Not
Good:
If ( name
== “” )
{
// do something
}
10.
Avoid using member variables. Declare local
variables wherever necessary and pass it to other methods instead of sharing a
member variable between methods. If you share a member variable between
methods, it will be difficult to track which method changed the value and when.
11.
Use enum wherever required.
Do not use numbers or strings to indicate discrete values.
Good:
enum MailType
{
Html,
PlainText,
Attachment
}
void SendMail (string message, MailType
mailType)
{
switch ( mailType )
{
case MailType.Html:
// Do something
break;
case MailType.PlainText:
// Do something
break;
case MailType.Attachment:
// Do something
break;
default:
// Do something
break;
}
}
Not
Good:
void SendMail (string message, string
mailType)
{
switch ( mailType )
{
case "Html":
// Do something
break;
case "PlainText":
// Do something
break;
case
"Attachment":
// Do something
break;
default:
// Do something
break;
}
}
12.
Do not make the member variables public or
protected. Keep them private and expose public/protected Properties.
13.
The event handler should not contain the code
to perform the required action. Rather call another method from the event
handler.
14.
Do not programmatically click a button to
execute the same action you have written in the button click event. Rather,
call the same method which is called by the button click event handler.
15.
Never hardcode a path or drive name in code.
Get the application path programmatically and use relative path.
16.
Never assume that your code will run from
drive "C:". You may never know, some users may run it from network or
from a "Z:".
17.
In the application start up, do some kind of
"self-check" and ensure all required files and dependencies are
available in the expected locations. Check for database connection in startup,
if required. Give a friendly message to the user in case of any problems.
18.
If the required configuration file is not
found, application should be able to create one with default values.
19.
If a wrong value found in the configuration
file, application should throw an error or give a message and also should tell
the user what are the correct values.
20.
Error messages should help the user to solve
the problem. Never give error messages like "Error in Application",
"There is an error" etc. Instead give specific messages like
"Failed to update database. Please make sure the login id and password are
correct."
21.
When displaying error messages, in addition
to telling what is wrong, the message should also tell what the user should do
to solve the problem. Instead of message like "Failed to update database.”
suggest what should the user do: "Failed to update database. Please make
sure the login id and password are correct."
22.
Show short and friendly message to the user.
But log the actual error with all possible information. This will help a lot in
diagnosing problems.
23.
Do not have more than one class in a single
file.
24.
Have your own templates for each of the file
types in Visual Studio. You can include your company name, copy right
information etc. in the template. You can view or edit the Visual Studio file
templates in the folder C:\Program Files\Microsoft Visual Studio
8\Common7\IDE\ItemTemplatesCache\CSharp\1033. (This folder has
the templates for C#, but you can easily find the corresponding folders or any
other language)
25.
Avoid having very large files. If a single
file has more than 1000 lines of code, it is a good candidate for refactoring.
Split them logically into two or more classes.
26.
Avoid public methods and properties, unless
they really need to be accessed from outside the class. Use “internal” if they
are accessed only within the same assembly.
27.
Avoid passing too many parameters to a
method. If you have more than 4~5 parameters, it is a good candidate to define
a class or structure.
28.
If you have a method returning a collection,
return an empty collection instead of null, if you have no data to return. For
example, if you have a method returning an ArrayList, always return a valid
ArrayList. If you have no items to return, then return a valid ArrayList with 0
items. This will make it easy for the calling application to just check for the
“count” rather than doing an additional check for “null”.
29.
Use the AssemblyInfo file to fill information
like version number, description, company name, copyright notice etc.
30.
Logically organize all your files within
appropriate folders. Use 2 level folder hierarchies. You can have up to 10
folders in the root folder and each folder can have up to 5 sub folders. If you
have too many folders than cannot be accommodated with the above mentioned 2
level hierarchy, you may need re factoring into multiple assemblies.
16.
Make sure you have a good logging class which
can be configured to log errors, warning or traces. If you configure to log
errors, it should only log errors. But if you configure to log traces, it
should record all (errors, warnings and trace). Your log class should be
written such a way that in future you can change it easily to log to Windows
Event Log, SQL Server, or Email to administrator or to a File etc. without any
change in any other part of the application. Use the log class extensively
throughout the code to record errors, warning and even trace messages that can
help you trouble shoot a problem.
17.
If you are opening database connections,
sockets, file stream etc., always close them in the finally block.
This will ensure that even if an exception occurs after opening the connection,
it will be safely closed in the finally block.
18.
Declare variables as close as possible to
where it is first used. Use one variable declaration per line.
19.
Use StringBuilder class instead of String
when you have to manipulate string objects in a loop. The String object works
in weird way in .NET. Each time you append a string, it is actually discarding
the old string object and recreating a new object, which is a relatively
expensive operations.
Consider the
following example:
public
string ComposeMessage (string[] lines)
{
string
message = String.Empty;
for
(int i = 0; i < lines.Length; i++)
{
message
+= lines [i];
}
return message;
}
In the above example,
it may look like we are just appending to the string object ‘message’. But what
is happening in reality is, the string object is discarded in each iteration
and recreated and appending the line to it.
If your loop has
several iterations, then it is a good idea to use StringBuilder class instead
of String object.
See the example where
the String object is replaced with StringBuilder.
public
string ComposeMessage (string[] lines)
{
StringBuilder
message = new StringBuilder();
for
(int i = 0; i < lines.Length; i++)
{
message.Append(
lines[i] );
}
return
message.ToString();
}
1.
Always use multi-layer (N-Tier) architecture.
2.
Never access database from the UI pages.
Always have a data layer class which performs all the database related tasks. This
will help you support or migrate to another database back end easily.
3.
Use try-catch in your data layer to catch all
database exceptions. This exception handler should record all exceptions from
the database. The details recorded should include the name of the command being
executed, stored proc name, parameters, connection string used etc. After
recording the exception, it could be re thrown so that another layer in the
application can catch it and take appropriate action.
4.
Separate your application into multiple
assemblies. Group all independent utility classes into a separate class
library. All your database related files can be in another class library.
1. Do not use
session variables throughout the code. Use session variables only within the
classes and expose methods to access the value stored in the session variables.
A class can access the session using System.Web.HttpCOntext.Current.Session
2.
Do not store large objects in session.
Storing large objects in session may consume lot of server memory depending on
the number of users.
3.
Always use style sheet to control the look
and feel of the pages. Never specify font name and font size in any of the
pages. Use appropriate style class. This will help you to change the UI of your
application easily in future. Also, if you like to support customizing the UI
for each customer, it is just a matter of developing another style sheet for
them
Good
and meaningful comments make code more maintainable. However,
1.
Do not write comments for every line of code
and every variable declared.
2.
Use // or /// for
comments. Avoid using /* … */
3.
Write comments wherever required. But good
readable code will require very less comments. If all variables and method
names are meaningful, that would make the code very readable and will not need
many comments.
4.
Do not write comments if the code is easily
understandable without comment. The drawback of having lot of comments is, if
you change the code and forget to change the comment, it will lead to more
confusion.
5.
Fewer lines of comments will make the code
more elegant. But if the code is not clean/readable and there are less
comments, that is worse.
6.
If you have to use some complex or weird
logic for any reason, document it very well with sufficient comments.
7.
If you initialize a numeric variable to a
special number other than 0, -1 etc, document the reason for choosing that
value.
8.
The bottom line is, write clean, readable
code such a way that it doesn't need any comments to understand.
9.
Perform spelling check on
comments and also make sure proper grammar and punctuation is used.
1.
Never do a 'catch exception and do nothing'.
If you hide an exception, you will never know if the exception happened or not.
Lot of developers uses this handy method to ignore non-significant errors. You
should always try to avoid exceptions by checking all the error conditions
programmatically. In any case, catching an exception and doing nothing is not
allowed. In the worst case, you should log the exception and proceed.
2.
In case of exceptions, give a friendly
message to the user, but log the actual error with all possible details about
the error, including the time it occurred, method and class name etc.
3.
Always catch only the specific exception, not
generic exception.
Good:
void ReadFromFile ( string fileName )
{
try
{
// read from file.
}
catch (FileIOException ex)
{
// log error.
// re-throw exception depending on your case.
throw;
}
}
Not
Good:
void
ReadFromFile ( string fileName )
{
try
{
// read from file.
}
catch (Exception ex)
{
// Catching general exception is bad...
we will never know whether
// it was a file error or some other
error.
// Here you are hiding an exception.
// In this case no one will ever know
that an exception happened.
return "";
}
}
4.
No need to catch the general exception in all
your methods. Leave it open and let the application crash. This will help you
find most of the errors during development cycle. You can have an application
level (thread level) error handler where you can handle all general exceptions.
In case of an 'unexpected general error', this error handler should catch the
exception and should log the error in addition to giving a friendly message to
the user before closing the application, or allowing the user to 'ignore and
proceed'.
5.
When you re throw an exception, use the throw statement
without specifying the original exception. This way, the original call stack is
preserved.
Good:
catch
{
//
do whatever you want to handle the exception
throw;
}
Not Good:
catch (Exception ex)
{
//
do whatever you want to handle the exception
throw
ex;
}
6.
Do not write try-catch in all your methods.
Use it only if there is a possibility that a specific exception may occur and
it cannot be prevented by any other means. For example, if you want to insert a
record if it does not already exists in database, you should try to select
record using the key. Some developers try to insert a record without checking
if it already exists. If an exception occurs, they will assume that the record
already exists. This is strictly not allowed. You should always explicitly
check for errors rather than waiting for exceptions to occur. On the other
hand, you should always use exception handlers while you communicate with
external systems like network, hardware devices etc. Such systems are subject
to failure anytime and error checking is not usually reliable. In those cases,
you should use exception handlers and try to recover from error.
7.
Do not write very large try-catch blocks. If
required, write separate try-catch for each task you perform and enclose only
the specific piece of code inside the try-catch. This will help you find which
piece of code generated the exception and you can give specific error message
to the user.
8.
Write your own custom exception classes if
required in your application. Do not derive your custom exceptions from the
base class SystemException. Instead, inherit from ApplicationException.
Regards,
Keyur Pandya
Keyur Pandya
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