struct

Boost Phoenix: Binding to reference members of structures?

I would like to use Boost Phoenix to generate a lambda function for use in a std::find_if operation on a structure that contains reference-type members. A contrived example is as follows: struct MyStruct { MyStruct() : x(0) {} int& x; }; std::vector<MyStruct> AllStructs; // Search the array for an element for which x == 5...

Problem with Struct and Pointer in C language.

I'm newbie. Pointer make my crazy T_T. Now, I'm do the socket programming project. This is my code. typedef struct { char *ip[INET6_ADDRSTRLEN]; char *username[20]; time_t login_time; enum client_state client_state; int no_login; } Client; Client client[max_connections] = {}; // set to nu...

struct with 2 cells vs std::pair ?

Possible Duplicate: What is the difference between using a struct with two fields and a pair? Dear all, I have a little question about pairs and struct. Is there any advantage to use a std::pair instead of a struct with two cells ? I have used pairs for a while but the main problem is readability : If you want to represent fo...

error C2440: '=' : cannot convert from 'char [5]' to 'char [20]'

This is linked to my previous post Wher I created a Struct : struct buffer { char ProjectName[20]; char ProjectID[20]; }; Now while I am trying to assign values to it: buffer buf; buf.ProjectID = "3174"; buf.ProjectName = "NDS"; I am getting this error: error C2440: '=' : cannot convert from 'char [5]' to 'char [20]' ...

How to deal with the immutability of returned structs?

I'm writing a game that has a huge 2D array of "cells". A cell takes only 3 bytes. I also have a class called CellMap, which contains the 2D array as a private field, and provides access to it via a public indexer. Profiling showed that a performance problem is caused by garbage collection of too many Cell objects. So I decided to make ...

strcpy in a struct gives SIGABRT

Hi, I'm currently working on an FTP client written in C, and it's working pretty good. I was successful in writing a function that connects to an FTP server and logs in with a username or password, but I'm having a problem with returning errors. I have setup a struct FTPError {}; with 3 fields: int An error code int An FTP error domain...

Can I return a struct from a WebMethod

I have a struct called Base64String which basically does implicit conversion between a string and a byte[] It's working quite well in the library, but here's the oddity... When I have a webservice, that returns the value as Base64String [WebMethod] public Base64String GetBase64String(string input) { return input; ...

How do I concatenate two strings and store them into the same struct key

I'm using Coldfusion. I want to concatenate two strings into the same struct key, but I keep getting an error of "can't convert x into a boolean." For example: <cfset myStruct.string1 = nodes[1].string1.XmlText> <cfset mystruct.string2 = nodes[1].string2.XmlText> Neither of the following works <cfset myStruct.concatendatedSring = n...

confused using reportlab to get RGB data from binary output of jpeg image reader?

for the reportlab library there is a module utils.py, and within this module a class class ImageReader(object): I was expecting to use this class to get RGB style data of integers between 0 and 255 but instead my code returns the following (1718461541,) for each print line below import struct filename = "pakistan.jpg" imageObj = u...

Will struct modifications in C# affect unmanaged memory?

My gut reaction is no, because managed and unmanaged memory are distinct, but I'm not sure if the .NET Framework is doing something with Marshaling behind the scenes. What I believe happens is: When getting a struct from my unmanaged DLL, it is the same as making that call gets an IntPtr and then uses it and the Marshal class to copy th...

When is it appropriate to use a cell array vs. a struct in Matlab?

If I want to store some strings or matrices of different sizes in a single variable, I can think of two options: I could make a struct array and have one of the fields hold the data, structArray(structIndex).structField or I could use a cell array, cellArray{cellIndex} but is there a general rule-of-thumb of when to use which data ...

Why does a struct consisting of a char, short, and char (in that order), when compiled in C++ with 4-byte packing enabled, come to a 6-byte struct?

I thought I understood how C/C++ handled struct member alignment. But I'm getting strange results for a particular arrangement in Visual Studio 2008 and 2010. Specifically, I'm finding that a struct consisting of a char, short, and char is compiled into a 6-byte struct, even with 4- or 8-byte packing enabled. I am at a loss as to why th...

Is it possible to create a reference-cycle using only value-types?

By way of explanation, take this value type in C#: struct ObjRef { public object Value; public ObjRef(object value) { Value = value; } } I can imagine an object graph where there are two boxed instances of this type, each holding a reference to the other. This is what I mean by a reference-cycle with only value-types. My ques...

Freeing struct with pointer and non-pointer variables

I'm trying to implement linked-lists with c struct, I use malloc to allocate a new node then allocate space for value, so I've been thinking how to free the structure once I'm done with them, my structure looks like this: typedef struct llist { char *value; int line; struct llist *next; } List; I have a function that wa...

How to have a Struct with template with a class

With this code (just a class of test): typedef unsigned short UInt16; template<class T> class CClass { public: SValue* getNewSValue(void); private: typedef struct { T *mValue; T *next; T *previous; UInt16 index; } SValue; }; template<typename T> SValue* CClass<T>::getNewSValue(void) { re...

How do you serialize a struct and store it in a MySQL database?

I am using C++ for an online game server project and I need to store some structs as binary blobs in a MySQL database. I am using RakNet for networking and have tried using its BitStream class to serialize the data but I don't know how to do it right. My question is, how do you turn a structure into a stream of bytes that you can pass in...

New to C and C Structures -- How to take a struct as a parameter in a function.

New to StackOverflow and new to C. I'm trying to take a struct as a parameter in a function 'add_fields', which adds the first two int fields 'a' and 'b' and puts the result in int field 'c'. Not getting anything from the compiler, so obviously I'm doing something wrong. I just don't know what. Any help would be appreciated. #inclu...

C++ [] mapping, possibly through templates

Hi, I have a little problem in C++ I don't know how to solve. The first part of the problem is to access an element in a struct via [], or better, to map [] to a subelement. My struct looks like this: struct e { std::string content; std::string name; std::map<std::string, std::vector<e> > elements; }; If I want to access ...

How can I assign a default value to a structure in a C++ function?

I have a structure: typedef struct { double x,y,z; } XYZ; I want to define a function like this: double CalcDisparity(XYZ objposition, XYZ eyeposition, double InterOccularDistance = 65.0) But I can't seem to find a way to assign a default value to eyeposition. How can I do this in C++...

struct sockaddr_un v/s sockaddr - C(Linux)

How is struct sockaddr different from struct struct sockaddr_un ? I know that we use these structures in client-server modules,for binding the socket to the socket address.And we use a cast operator for it to accept struct sockaddr_un. I want to know how different/similar are they,and why the cast operator? ...