switch-statement

问题 I wish to accomplish a fairly simple task (I hope!) I got two div tags and one anchor tags, like this: <a href="javascript:void(0);">forgot password?</a> <div id="login-form"></div> <div id="recover-password" style="display:none;"></div> I wish use the anchor tag to toggle between the two div tags, hide the one and show the other and vice versa. How can this be done the best way? 回答1: Since one div is initially hidden, you can simply call toggle for both divs: <a href="javascript:void(0);" id

问题 Here's an excerpt from Sun's Java tutorials: A switch works with the byte , short , char , and int primitive data types. It also works with enumerated types (discussed in Classes and Inheritance) and a few special classes that "wrap" certain primitive types: Character , Byte , Short , and Integer (discussed in Simple Data Objects). There must be a good reason why the long primitive data type is not allowed. Anyone know what it is? 回答1: I think to some extent it was probably an arbitrary

问题 This question already has answers here : scanf() leaves the new line char in the buffer (4 answers) Closed 8 months ago . I wrote a program using switch case statement and asked for a char for input but it does not ask for the char in the console window but skips it completely int main() { float a, b, ans; char opr; printf("\nGIVE THE VALUES OF THE TWO NUMBERS\n"); scanf(" %f %f",&a,&b); printf("\nGIVE THE REQUIRED OPERATOR\n"); //no display(echo) on the screen //opr = getch(); //displays on

问题 With JDK/12 EarlyAccess Build 10, the JEP-325 Switch Expressions has been integrated as a preview feature in the JDK. A sample code for the expressions (as in the JEP as well): Scanner scanner = new Scanner(System.in); Day day = Day.valueOf(scanner.next()); switch (day) { case MONDAY, TUESDAY -> System.out.println("Back to work.") ; case WEDNESDAY -> System.out.println("Wait for the end of week...") ; case THURSDAY,FRIDAY -> System.out.println("Plan for the weekend?"); case SATURDAY, SUNDAY -

问题 Java documentation says The Java compiler generates generally more efficient bytecode from switch statements that use String objects than from chained if-then-else statements. AFAIK even String in switch uses .equals() internally in a case sensitive manner. So what efficiency do they mean in this context. Faster compilation? Less bytecodes ? better performance? 回答1: Using a switch statement is faster than equals (but only noticeably when there are more than just a few strings) because it

问题 My code is as follows: public static void Output<T>(IEnumerable<T> dataSource) where T : class { dataSourceName = (typeof(T).Name); switch (dataSourceName) { case (string)typeof(CustomerDetails).Name.ToString(); : var t = 123; break; default: Console.WriteLine("Test"); } } But this is not working. The case statement is giving me an error saying that a constant variable is expected. Please help guys thank you! 回答1: See C# switch statement limitations - why? Basically Switches cannot have

问题 In C there is a switch construct, which enables one to execute different conditional branches of code based on an test integer value, e.g., int a; /* Read the value of "a" from some source, e.g. user input */ switch ( a ) { case 100: // Code break; case 200: // Code break; default: // Code break; } How is it possible to obtain the same behavior (i.e. avoid the so-called " if - else ladder") for a string value, i.e., a char * ? 回答1: If you mean, how to write something similar to this: //

问题 I'm making a function to return whether or not the given user_id is a staff member of the site. This is what I have and it works, however I feel like it can be greatly improved. public function isUserStaff($uid) { $stmt = $this->conn->prepare("SELECT user_role FROM users WHERE user_id=:user_id"); $stmt->execute(array(':user_id'=>$uid)); $userRow = $stmt->fetch(PDO::FETCH_ASSOC); $role = $userRow['user_role']; switch($role) { case 3: return true; break; case 4: return true; break; case 5:

问题 I'm making a function to return whether or not the given user_id is a staff member of the site. This is what I have and it works, however I feel like it can be greatly improved. public function isUserStaff($uid) { $stmt = $this->conn->prepare("SELECT user_role FROM users WHERE user_id=:user_id"); $stmt->execute(array(':user_id'=>$uid)); $userRow = $stmt->fetch(PDO::FETCH_ASSOC); $role = $userRow['user_role']; switch($role) { case 3: return true; break; case 4: return true; break; case 5:

问题 I have two tables... tblEvent -------- id date tblEventRecurring ----------------- event_id date_part end_date The relationship is I can have an event that is either on one day (date in tblEvent) or recurs on an interval (Day, Week, Month, Year) which ties in the tblEventRecurring table. For example, if I put in an event for Feb. 10 recurring until Feb. 28 I'd have... tblEvent -------- id = 1 date = 2012-02-10 tblEventRecurring ----------------- event_id = 1 date_part = D end_date = 2012-02