members

问题 Do unions have a control structure to test which member is currently in use (or if it has any at all)? I'm asking this because undefined behavior is never a good thing to have in your program. 回答1: No, no such mechanism exists off-the-shelf. You'll have to take care of that yourself. The usual approach is wrapping the union in a struct : struct MyUnion { int whichMember; union { //whatever } actualUnion; }; So you have MyUnion x; and x.whichMember tells you which field of x.actualUnion is in

问题 Note: This question is not a duplicate of How can I get all object vals and subobject vals using reflection in Scala? The answer provided in that question only works for final members. For example: scala> object Settings { | val Host = "host" | } defined module Settings deepMembers(Settings) res0: Map[String,String] = Map() 回答1: It must be a duplicate, but I need a refresher: $ scala Welcome to Scala version 2.11.7 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_45). Type in expressions to

问题 Note: This question is not a duplicate of How can I get all object vals and subobject vals using reflection in Scala? The answer provided in that question only works for final members. For example: scala> object Settings { | val Host = "host" | } defined module Settings deepMembers(Settings) res0: Map[String,String] = Map() 回答1: It must be a duplicate, but I need a refresher: $ scala Welcome to Scala version 2.11.7 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_45). Type in expressions to

问题 This question already has answers here : Closed 8 years ago . Possible Duplicate: JavaScript setAttribute vs .attribute= javascript dom, how to handle "special properties" as versus attributes? Many times, in forums or places such as Usenet I have been told by some (when criticizing my code) that instead of saying, for example var link = a.href I should use var link = a.getAttribute('href'); instead. And use its complementary setAttribute() when wanting to assign. They say it is the correct

问题 I have a basic membership system set up using MySQL database with 3 tables, user_id, user_name and user_password. my php code bellow is simple as I am new to php and will develop it further as my knowledge progresses. I am trying to create different rolls at the moment, member, admin and global admin. I am a bit lost on how to progress on from what I have so far. any advice or suggestions will be very much appreciated. my basic membership code <?php session_start(); $errorMessage = ''; if (

问题 Is there any considerations to determine which is better practice for creating an object with private members? var object = new function () { var private = "private variable"; return { method : function () { ..dosomething with private; } } } VS var object = function () { ... }(); Basically what is the difference between using NEW here, and just invoking the function immediately after we define it? 回答1: The new operator causes the function to be invoked like a Constructor Function. I've seen

问题 Okay. Now I give up. I have been playing with this for hours. I have a variable name $data . The variable contains these contents: (extracted by using var_export() ) array ( 'headers' => array ( 'content-type' => 'multipart/alternative; boundary="_689e1a7d-7a0a-442a-bd6c-a1fb1dc2993e_"', ), 'ctype_parameters' => array ( 'boundary' => '_689e1a7d-7a0a-442a-bd6c-a1fb1dc2993e_', ), 'parts' => array ( 0 => stdClass::__set_state(array( 'headers' => array ( 'content-type' => 'text/plain; charset=

问题 I'm using Custom Post Type and "Members" plugin in wordpress. My problem is that in my custom post type I can't delete posts, the link to move to trash is not there :( Here is my code: 'capabilities' => array( 'edit_post' => 'edit_entrada_tallers_activitats_grups', 'read_post' => 'read_entrada_tallers_activitats_grups', 'delete_post' => 'delete_entrada_tallers_activitats_grups', 'delete_posts' => 'delete_entradas_tallers_activitats_grups', 'delete_others_posts' => 'delete_others_entradas

问题 There is an object who's members I need to find the size of. I am specifically asking for the object's size without it's v-table considered. Also, I cannot modify it, so I cannot take advantage of this answer. Is there a provision for this in C++, beyond summing a hard-coded sizeof for each member? I am aware that v-tables are not mandated by C++. I am also aware that anything I do with this information will be widely considered "bad form". This question is simply asking if it's possible, not

问题 might be a bit of a coward-ish question: I've got two classes, and declared all variables public. Why can't I access the variables from derived class?? g++ tells me: vec3d.h:76:3: error: ‘val’ was not declared in this scope template<typename TYPE> class vec{ public: TYPE *val; int dimension; public: vec(); vec( TYPE right ); vec( TYPE right, int _dimension ); [etc] template<typename TYPE> class vec3d : public vec<TYPE>{ public: vec3d() : vec<TYPE>( 0, 3 ){}; vec3d( TYPE right ) : vec<TYPE>(