member | 易学教程

how to pass a non static-member function as a callback?

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问题 io_iterator_t enumerator; kern_return_t result; result = IOServiceAddMatchingNotification( mNotifyPort, kIOMatchedNotification, IOServiceMatching( "IOFireWireLocalNode" ), serviceMatchingCallback, (void *)0x1234, & enumerator ); serviceMatchingCallback((void *)0x1234, enumerator); if i declare serviceMatchinCallback as static then it works, but i do not want it to be static. Is there a way to pass it a non-static callback function? Thank you 回答1: You could keep it static, but use the userdata

INSERT EXEC 语句

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INSERT EXEC语句可以把存储过程或动态SQL批处理返结果集插入目标数据表中，下面例子是以存储过程返回结果集插入一个表变量中，演示例子，首选创建一个存储过程，这个存储过程需要传入一个参数，是否在职的Member。代码 IF OBJECT_ID ( ' dbo.usp_Member_Job ' , ' p ' ) IS NOT NULL DROP PROCEDURE dbo.usp_Member_Job GO CREATE PROCEDURE dbo.usp_Member_Job @IsJob BIT AS IF @IsJob = 1 SELECT [ MemberId ] , [ Name ] , [ Job ] FROM [ dbo ] . [ Member ] WHERE [ Job ] = @IsJob ELSE SELECT [ MemberId ] , [ Name ] , [ Job ] FROM [ dbo ] . [ Member ] WHERE [ Job ] = @IsJob OR [ Job ] IS NULL 创建一个表变量, DECLARE @IsJobMember AS TABLE ( [ MemberId ] [ int ] NOT NULL , [ Name ] [ nvarchar ] ( 100 ) NOT NULL , [ Job ]

How to use return value from method in Java?

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问题 I want to use the return value from a member function by storing it into a variable and then using it. For example: public int give_value(int x,int y) { int a=0,b=0,c; c=a+b; return c; } public int sum(int c){ System.out.println("sum="+c); } public static void main(String[] args){ obj1.give_value(5,6); obj2.sum(..??..); //what to write here so that i can use value of return c //in obj2.sum } 回答1: try int value = obj1.give_value(5,6); obj2.sum(value); or obj2.sum(obj1.give_value(5,6)); 回答2:

C++ < 11 : Initialize static const class member

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问题 So I have a class which has mostly static stuff because it needs to be a library accessible at all times with no instantiation. Anyway, this class has a public static member, a structure called cfg, which contains all of its configuration parameters (mostly boundaries and tolerances for the algorithms implemented by its static methods). And on top it has a const static member, which is a structure of the same type as cfg, but has all the default / usual values for the parameters. Users of my

C++ < 11 : Initialize static const class member

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c - error: request for member xxxxxx in something not a structure or union

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问题 This is in a program meant to work with ppm image files. I'm getting a compilation error when trying to use a function that accepts a global struct variable and extracting that image's members. This is the global struct (declared in ppmIO.c and ppmIO.h): ppmIO.c: struct Image *instance; ppmIO.h: struct Image { int width; int height; unsigned char *data; }; extern struct Image *instance; This is how I call my function from main: ImageInvert(&instance); These are the relevant parts of my

Find the shortest path between two nodes in a graph in (Prolog) and display the result as array

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问题 [ ] How can I write (using print_path ) a rule to print the path from one node to another if exists Print_path(a, c, Res) ---> Res=[a, f, c] What I did was : path(a,b). %there is a path from a to b path(a,f). path(b,c). path(c,d). path(c,e). path(e,d). path(f,g). path(f,c). path(f,e).` I do not know what to do next. 来源： https://stackoverflow.com/questions/41112132/find-the-shortest-path-between-two-nodes-in-a-graph-in-prolog-and-display-the

Retrieving and editing private members of objects in a vector

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问题 I have some code which adds a few objects to a vector. I then wish to retrieve a specific object from the vector and be able to both write out and edit its private member variables. This is the code I currently have: class Product { public: Product(int n, const string& na, int p) : number(n), name(na), price(p) {}; void info() const; private: string name; int number, price; }; The member function looks like this: void Product::info() const { cout << number << ". " << name << " " price << endl

Implementing vanity URL for individual users in PHP

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问题 How would one go about implementing a vanity URL for each user in PHP? I'm implementing my web-app's login system as a tweaked version of the Drax LLP Login system. So, each user should be able to modify his profile which will finally appear on his vanity URL .. like xyz.com/user. Any tips / ideas? Thanks.. 回答1: Here's an example of the files involved: .htaccess: <IfModule mod_rewrite.c> RewriteEngine on RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule .

identifier int not a direct member of struct SOCKET_LOG_DATA

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问题 When I compile the below struct:- typedef PACKED struct PACKED_SUFFIX SOCKET_LOG_DATA { typedef PACKED union PACKED_SUFFIX { PACKED struct PACKED_SUFFIX { UINT16 loss_reason : 1; UINT16 unused : 15; } fields; UINT16 all_fields; } ; UINT16 socket_number; SOCKET_LOG_DATA () : all_fields(0), socket_number(0) {} } SOCKET_LOG_DATA; I get compilation error that:- error (dplus:1384): identifier all_fields not a direct member of SOCKET_LOG_DATA How do I fix this? 回答1: I fixed this with proper