default-value

The following code won't compile. Why? class A { int j; void f( int i = this->j ); } Edit, for clarity. This is what I was trying to do, using less lines of code... class A { void f( int i ){}; void f( ); int j; }; void A::f() { f( j ); } Eric Default argument values are bound at compile time. "this" is only defined at run time, so can't be used. See here for a fuller explanation: Must default function parameters be constant in C++? Others have already commented on the reason this doesn't work. From one of the comments: "...The expression can combine functions that are visible in the current

I have what I think should be a simple problem. I have an inline model formset, and I'd like to make a select field have a default selected value of the currently logged in user. In the view, I'm using Django's Authentication middleware, so getting the user is a simple matter of accessing request.user . What I haven't been able to figure out, though, is how to set that user as the default selected value in a select box (ModelChoiceField) containing a list of users. Can anyone help me with this? I'm not sure how to handle this in inline formsets, but the following approach will work for normal

I have Python code that looks like: if key in dict: dict[key].append(some_value) else: dict[key] = [some_value] but I figure there should be some method to get around this 'if' statement. I tried dict.setdefault(key, []) dict[key].append(some_value) and dict[key] = dict.get(key, []).append(some_value) but both complain about "TypeError: unhashable type: 'list'". Any recommendations? Thanks! The best method is to use collections.defaultdict with a list default: from collections import defaultdict dct = defaultdict(list) Then just use: dct[key].append(some_value) and the dictionary will create a

I have this code: if(isset($_POST['search'])) { $res1=mysql_query("SELECT * FROM aircraft where acode = '$_POST[ac]'") or die(mysql_error()); while($row=mysql_fetch_array($res1)) { $airc=$row['acode']; $amode=$row['amodel']; $stat=$row['status']; $rem=$row['remarks']; echo "<center><table><form name=\"frmMain\" method=\"post\"> <tr><td><font face=consolas><b>Aircraft Code:</b></font></td><td><input type=text name=arc value='$airc' readonly=readonly></td></tr> <tr><td><font face=consolas><b>Aircraft Model:*</b></font></td><td><input type=text name=am value='$amode'></td></tr> <tr><td><font face

I have a simple script in jQuery that works perfectly with jQuery 1.5.2 as you can see in this jsFiddle . What is supposed to happen is that when you bring focus to the text field, the default value is removed. And when if you leave the field blank, the original default value is put back in place. http://jsfiddle.net/kHBsD/ However, the same exact code, where only jQuery 1.6.3 is used instead, is not working. (Not working means that the default value remains in the text box until you manually delete it as you can see in this jsFiddle . http://jsfiddle.net/kHBsD/1/ There are no script errors in

How to set default value for a field to other column in Mysql I have done it oracle with virtual field but I do not know how to do it in Mysql this is my table: create table TSM_TRANSACTION_TBL ( TRANS_ID INT primary key auto_increment, LOCATION_ID INT, TRANS_DATE DATE, RESOURCE_ID INT, TS_ID INT, MAX_VALUE INT, BOOKED_UNITS INT default 0, REMAINING INT default MAX_VALUE - BOOKED_UNITS, BOOKED INT not null, USER_ID INT, TRANS_TIME TIMESTAMP ) eggyal As documented under Data Type Default Values : The DEFAULT value clause in a data type specification indicates a default value for a column. With

The question is simple: #include <iostream> enum SomeEnum { EValue1 = 1, EValue2 = 4 }; int main() { SomeEnum enummy; std::cout << (int)enummy; } What will be the output? Note: This is not an interview, this is code inherited by me from previous developers. Streaming operator here is just for example, actual inherited code doesn't have it. The program has Undefined Behavior . The value of enummy is indeterminate. Conceptually there is no difference between your code and the following code: int main() { int i; //indeterminate value std::cout << i; //undefined behavior }; If you had defined your

Possible Duplicate: What do the following phrases mean in C++: zero-, default- and value-initialization? If I have a class for example: class Info { int x; int y; }; which I used to created an object, Info *p = new Info(); Does the brackets beside Info mean i'm value initializing it? How does it different from this, Info *p = new Info; ? I know there is a question which differentiate between different meanings in new and old C++ language but I want to know the semantic difference between default and value initialization e.g. Does value initialization means initializing something to zero? A

My question somewhat overlaps with this and several other similar ones. Those have some great answers, but I've read them and I'm still confused, so please don't consider this question a duplicate. So, I have the following code: class A { public: int _a; } void main() { A inst1; A* inst2 = new A; A* inst3 = new A(); } _a is left uninitialized in inst1 and inst2 and is initialized to 0 in inst3 . Which initialization is called which, and why does the code work as it does? Please take into I account I don't have a C++ 03 standard at hand, but I have the last C++ 11 draft (I'm programming by '03