ASP.NET

Re: comapring condition in if

28-Apr-06 21:38

yogsworld wrote:
is both are same ?????????

Yes, the are both the same.

The reason you might see some people using the first varient is that in some languages (e.g. C, C++), if you made a mistake and typed

if (variableName = null)

by accident the compiler would accept it. (Note the single equal of assignment). By putting the constant on the left hand side of the operator the compiler would reject the assignment and the developer would realise they missed the extra equals sign.

In .NET, the langage specififcation states that the result of an if statement must be a boolean so the compiler would reject an assignment in an if statement. It will give the error message

Cannot implicitly convert type 'object' to 'bool'.

If someVariable was a boolean the error message you'd get is

Cannot convert null to 'bool' because it is a value type

However, there is one scenario where the compiler will accept an assignment in an if statement. That is, if the assignment evalulates to a boolean. e.g.

bool someVariable;
if (someVariable = false) {}

The compiler will compile this, but issue a warning instead

Assignment in conditional expression is always constant; did you mean to use == instead of = ?

Does this help?

"On two occasions, I have been asked [by members of Parliament], 'Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?' I am not able to rightly apprehend the kind of confusion of ideas that could provoke such a question."
--Charles Babbage (1791-1871)
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yogsworld29-Apr-06 0:05

yogsworld

29-Apr-06 0:05

hi
i didn't get your ans ... I just simply ask

difference bet if ( someVarial == null) and if (null == somevariable)
i.e position of nulll should be first or not I know both expression are evaluating same result.but if u see some code they comaore like
if (null == someVarible) i.e position of null is first why ??????

Here someVarible is an refrence type not a value type ......

YOgesh M

Re: comapring condition in if

Colin Angus Mackay29-Apr-06 0:29

29-Apr-06 0:29

yogsworld wrote:
position of null is first why ??????

I explained why. It is a historical thing. Developers who programmed in languages such as C or C++ put null first as a way of protecting themselves by having the compiler flag an error to them. The error being the accidental missing equals sign.

= means assignment
== means a comparison

These two concepts produce radically different results, yet are very very easy to accidentally mix up. Someone typing fast may miss one of the equals signs.

In C# the compiler demands that the result of the conditional expression in an if statement evaluates to a Boolean value. I demonstrated the various error messages that the C# compiler would generate that a C or C++ compiler would not likely generate.

I should clarify: Putting the null first is not completely the same as putting it second IF there is an error in the code. If the code is written correctly with the double-equals (comparison) operator then the code is the same.

Does this make sense?

Memory leaks

karthiBalu28-Apr-06 18:35

karthiBalu

28-Apr-06 18:35

We have a system that uses Asp.net and Sql with c# as the back end, when we run the system it catches most of the RAM space,

why is this happening?
whats the solution for this problem

waiting for an reply ASAP

with regards,

KarthiBalu

Re: Memory leaks

Colin Angus Mackay28-Apr-06 21:26

Help Trying Connect to SQL

28-Apr-06 21:26

karthiBalu wrote:
when we run the system it catches most of the RAM

Because the memory manage sees that it can. If something else needs the memory then the memory manage will kick off a garbage collection and recover the memory.

ALQallaf28-Apr-06 16:16

28-Apr-06 16:16

Im new in SQL, im trying to connect to sql data base but it give me exception-->(Login failed for user ''. The user is not associated with a trusted SQL Server connection.)
i think there is wrong with SqlConnection parameter, so what is the wrong?
im with sql express 2005 & vs2005

SqlConnection SQLConn;
SQLConn = new SqlConnection( " Data Source = .\\SQLEXPRESS;" + "
Initial Catalog = MTDB; " );
SQLConn.Open();

isroavi28-Apr-06 17:24

isroavi

28-Apr-06 17:24

you did not mentioned uid and pwd.
or ty OLDDBConneciton object.

raj

ALQallaf29-Apr-06 4:24

29-Apr-06 4:24

im using Windows Authentication so what is my user id and password will be ?

Colin Angus Mackay29-Apr-06 4:50

29-Apr-06 4:50

If you are using Windows Authentication then you do not pass a user name and password.

Colin Angus Mackay28-Apr-06 21:24

28-Apr-06 21:24

Does the user your process is running as (ASPNET probably) have permission to log on to the database. By default the answer is no. You must add a login to SQL Server to accept the user you are connecting as. You must also add that user to the database on the server you want to connect to.

You have not specified a user in your connection string so I'm guessing that it will just default to trying to use a trusted connection (the error message hints at this also). ASP.NET applications connect using a special locked down account (for security). That account is generally ASPNET, although on some operating systems it will use another account (Win Srv 2003 will use NT AUTHORITY\NETWORK SERVICE)

ALQallaf29-Apr-06 4:23

29-Apr-06 4:23

im using Authentication: Windows Authentication, so i did not entered username or password , for this reasone i did not specified a user in my conection string, i dont know if i have to put a user , if yes i have to then what is my user will be ?

thanks

Colin Angus Mackay29-Apr-06 5:03

29-Apr-06 5:03

You might find this article useful: How To: Connect to SQL Server Using Windows Authentication in ASP.NET 2.0[^]

Kanjinghat4-May-06 3:29

Kanjinghat

4-May-06 3:29

the connection string should include "Integrated Security=SSPI".

that is

SQLConn = new SqlConnection( " Data Source = .\\SQLEXPRESS;" + " <br />
Initial Catalog = MTDB; Integrated Security=SSPI " );

hope this will help you.

Cheers

Ramesh.Kanjinghat

ALQallaf4-May-06 7:16