what is the data types I get from the database by SqlDataReader

[lucoin]

I am using asp.net(C#) to build a login sys. I use the SqlDataReader to get the data from the data base to validate the user. but it always comes the password dosn't matches. but I tested to print the password get from the database and user input on the page, they are the same. can any one tell me why?

I use text box to get user input
like sting userpwd = textbox.text..ToString().Trim();

and SqlDataReader sdr = cmd.ExecuteReader();
.......
if(str["Password"]==userpwd){}
.......
in the database, the password type is char(16)

[Plater]

Are you making sure to cast the str["Password"] object as a string?
Because if it's still referenced as an object, then it will do an object compare against the string (which would be false) and not a string comparison.

[lucoin]

Are you making sure to cast the str["Password"] object as a string?
Because if it's still referenced as an object, then it will do an object compare against the string (which would be false) and not a string comparison.

Thanks. That's the problem.

I forgot to add .Trim();

[r035198x]

Are you making sure to cast the str["Password"] object as a string?
Because if it's still referenced as an object, then it will do an object compare against the string (which would be false) and not a string comparison.

Actaully the == operator has the effect of calling ToString on the object so that == is done against two Strings. Thus for

object o = "object";
string s = "object";

s == o returns true.

@OP calling Trim for password comparisons is rather odd. What if I want a password that ends with two spaces? I suggest you investigate where the extra spaces are coming from and solve that.

[Plater]

Actaully the == operator has the effect of calling ToString on the object so that == is done against two Strings.

Learn something new everyday.