C/C++ :: Value Assignment To Structure Member Inside The Structure?
Oct 7, 2014Is it possible to assign a value to structure member inside the structure.like.....
struct control{
char tbi:2 =0;
char res:1 =0;
};
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C :: Set Struct Member Variable For Structure Inside Def
Mar 12, 2014This is with Linux gcc
Code:
typedef struct _a
{
int id;
} a;
typedef struct _b
{
a my_a;
my_a.id = 1; // error: expected specifier-qualifier-list before "my_a"
} b;
I get error: expected specifier-qualifier-list before "my_a"
I must set the id for the kind of struct created inside the struct def because main() will be casting based on this id. Thats how I will know which structure b contains by it's id, there could be hundards of different structs with different values I will cast to the correct one and know it's members by it's id. How do I ?
C++ :: Composition And Member Access Inside Composed Structure
Jan 18, 2013I have a question regarding composition and accessing members "deep" inside the composed structure. For example;
class A {
private:
int m_myInt;
public:
int myInt() const {return this->m_myInt;};
void myInt(int newInt) {this->m_myInt = newInt;};
[Code] ....
Now, from somwhere I have access to an object of type B where I want to update the A::m_myInt. How would you do this without "breaking" the whole purpose of private/public members?
B myB;
myB.m_a.myInt(3); // Not allowed, and not desireable
I thought about implementing access through functons kind of like;
A & B::a() {return this->m_a;};
myB.a().myInt(3);
but I'm worried that this exposes my B::m_a-object too much. This would allow
myB.a() = A();
, right?
The following is a more desireable way of acces, but doesn't work for updating;
A const & B::a() {return this->m_a;};
myB.a().myInt(3); //Disallowed? myInt(int) is non-const.
What about this? Is this a good way of doing it?
class A {
private:
int m_myInt;
public:
int myInt() const {return this->m_myInt;};
[Code] ....
I guess it works? It would lead to a lot of data shuffling in case of larger sub-components.I would really like to do the following without exposing my components so much:
B myB;
myB.a().myInt(3);
Can it be done?
C/C++ :: Not Able To Initialize Structure Variable Inside Main Whose Structure Defined GL
Aug 27, 2013I am trying to run a programme implementing a function with structures in c... which is:
#include<stdio.h>
#include<conio.h>
struct store {
char name[20];
float price;
int quantity;
[Code] .....
C++ :: How To Use Structure Pointer Through A Structure Public Member Definition
Dec 7, 2014Why doesn't this compile?
struct hi(){
void other();
}histructure;
void hi::other(){
std::cout << "Hi!" << std::endl;
[Code] ....
Makes no sense the structure is written before the structure member function is called so why is there compile errors ??...
C :: Uninitialized Variables Inside A Structure
Aug 7, 2013Let me say I have a structure
Code:
struct time{
char hours;
char minutes;
char seconds;
char dummy;
};
I have kept dummy as the data to be aligned.I will update hours, minutes, and seconds , but will not use dummy in any case. If I don't initialize 'dummy' does it make any errors ? Do I need to initialize hours, minutes, seconds as well before I use the structure ? If so is there any particular reason ?
C++ :: How To Define Enumeration Inside A Structure And Use It In Other File
Mar 5, 2014I want to define enumeration inside a structure and use it in some other file
for eg
header.h
typedef struct dummy {
typedef enum {
ZERO,
ONE,
MAX
} NUMBERS;
// some member variables
} DUMMY; // end of the structure
otherfile.cpp
in this file i want to access both enumerations(for eg) ONE as well as the type NUMBERS.
C/C++ :: Not Displaying Values Inside Structure Array (GCC)?
Apr 22, 2014#include <stdio.h>
#include <string.h>
#define MAX 22
struct inven {
int Iid;
double uprice;
int uoh;
char name[MAX];
[code].....
doesn't seem to want to display the disp* fucntions at all
C/C++ :: Accessing Pointer Inside A Nested Structure
Mar 19, 2014i had a structure as follows:
struct a{
int x;
struct b{
int y;
b *next;
}b;
};
when i try to access as follows:
struct a *a;
a->b=a->b->next;
i got the following error: base operand of ‘->’ has non-pointer type
C++ :: Malloc For Union Inside Structure Fails
Dec 27, 2012I have some problem while allocating memory to a union inside structure. Below is the code i am using
ON SYSTEM1:
This works fine
ON SYSTEM2:
compiler complains saying "need structure or union type" while allocating MYSTRUCT1.
If I change:
shreyas[0].UnionAttr.struct1 = (MYSTRUCT1 *) malloc (sizeof(MYSTRUCT1)
to
shreyas[0].UnionAttr->struct1 = (MYSTRUCT1 *) malloc (sizeof(MYSTRUCT1)
This compiler on SYSTEM2 is happy. but second way does not look correct to me and compiler on system 1 complains about it. Which is the correct way to allocate memory?
If first one is correct then what should i look in for to avoid this error? Could this be an issue with compiler on SYSTEM2? If i use second method on SYSTEM2 code segfaults during malloc.
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
typedef struct mystruct1 {
int a;
int b;
[Code] ....
C++ :: Why Is Structure Member Not Displaying
Jan 7, 2015I have started working with structures so here's a side project from my text book. It's purpose is fairly simple; it asks for the sales of each quarter of the year from 4 different divisions and then calculates the average quarterly sales and total annual sales and finally displays all the data. My problem is that in the function "displayCompanyInfo" the statement
std::cout << "Division " << R.division_name << std::endl;
does not display the name of the division. With that in mind here is the code:
#include <iostream>
#include <string>
struct CompanyInfo
{
[Code]....
As you can see the last part of the output has statements that say "Division" however they do not say the name of the division afterwards. I don't understand why that is?
C :: How To Assign String Hello To Structure Member
Feb 17, 2015See the simple code below. The compiler gives message:
assigning to type "char[20]" from type "char *".
I've tried everything else that seems reasonable but none works. How can I assign string Hello to the structure member?
Code:
int main() {
struct strc1
{
char msg1[20];
char msg2[5];
}
talk;
talk.msg1 = "Hello";
}
C++ :: Dynamic Table As A Structure Member?
Mar 24, 2014is it possible to make something like that?
struct type_name
{
char Status[i];
string Status[j];
.
.
} object_names;
The problem is I dont know how many statuses my object will have. Is it possible to make it in an dynamic array?
C++ :: Set Member To Same Value In All Instances Of Templated Structure
Sep 3, 2013template <typename T> struct avl_tree {
T data;
int balance;
struct avl_tree <T> *Link[2];
static int (*comp)(T, T);
};
In main, I have a function like so:
int compare(int a, int b) {
return ( a - b );
}
Now how do I assign the function pointer in my avl_tree class to the compare function?
I did this:
int (avl_tree<int>::*comp)(int, int) = compare;
But I got the compiler error:
Tree_Test.cc: In function ‘int main()’:
Tree_Test.cc:27:42: error: cannot convert ‘int (*)(int, int)’ to
‘int (avl_tree<int>::*)(int, int)’ in initialization
C/C++ :: Assigning Value From Struct Member To Outside Structure
Jun 20, 2013I have the code bellow, and i print the data but cannot assign it to global variable.
struct frequency_data {
char frequency[10];
int32 frequenca_mesatare;
int16 PWM_F;
int32 PR2;
[Code] ....
C++ :: Pass Pointer To Member Function (polymorphic Structure)?
Jan 3, 2015I am trying to create a callback system for input events in my game engine.
Here is a cut down version of the EventManager.h file
#include "Controls.h"
#include "Object.h"
enum MouseEventType{PRESSED, POINTER_AT_POSITION, PRESSED_AT_POSITION };
[Code].....
This works if the function pointer being passed to the event manager is not a member function.
I have two other classes Scene and Object that could potentially use this EventManager to create callback events. Scene and Object are both pure virtual objects. How can I pass a pointer to a member function of the child classes of both Scene and Object? I am fine with just having two separate watchEvent functions for Scene and Object but how do I pass the type of the Object or the type of the Scene? The child classes are unknown as they are being created by someone using this game engine.
For example, if I want to make a player object it would be something like
class PlayerObject : public Object{...};
Now that PlayerObject type has to find its way to PlayerObject::functionToCall(). I think I need templates to do this but, since I never used them before
This is how I intend to use this
class OtherScene : public Scene{
void p_pressed(void){
//pause
}
[Code].....
C :: How To Create A Structure That Pointing To Another Different Structure
Mar 17, 2013how I can create a structure that pointing to another different structure. And also passing structure to function.
View 3 Replies View RelatedC :: Calling Function Via Function Pointer Inside Structure Pointer
Mar 14, 2013I'm trying to call a function via a function pointer, and this function pointer is inside a structure. The structure is being referenced via a structure pointer.
Code:
position = hash->(*funcHash)(idNmbr);
The function will return an int, which is what position is a type of. When I compile this code,
I get the error: error: expected identifier before ( token.
Is my syntax wrong? I'm not sure what would be throwing this error.
C++ :: Accessing Inside Structure Via Struct Pointer To Struct Pointer
Jun 5, 2012"
#include <stdio.h>
struct datastructure {
char character;
};
void function(struct datastructure** ptr);
[Code] ....
These codes give these errors:
error: request for member 'character' in '* ptr', which is of non-class type 'datastructure*'
error: request for member 'character' in '* ptr', which is of non-class type 'datastructure*'
These errors are related to
"
*ptr->character='a';
printf("Ptr: %c",*ptr->character);
"
I want to access "character" data inside the structure "trial" by a pointer to pointer "ptr" inside function "function",but I couldn't find a way to do this.
C++ :: Assignment Operator But With Some Member Exceptions
Jan 9, 2015The task is to use the assignment operator of a class, but change all the data except certain ones. For example, below we are to assign all Person data of 'other' except for 'name' and 'ID':
#include <iostream>
#include <string>
struct Person {
std::string name;
int ID, age, height, weight;
[Code] .....
Name = Bob
ID = 2047
Age = 38
Height = 183
Weight = 170
Name = Frank
ID = 5025
Age = 25
Height = 190
Weight = 205
Bob pretends to be Frank, but keeps his name and ID.
Name = Bob
ID = 2047
Age = 25
Height = 190
Weight = 205
But I think the way I did it is pretty lousy (note the wasted steps changing the name and ID only to revert them back? So the ideal solution should require no wasted steps, unlike the method above, and changes to what the exclusions should be should be in only one place (not two like above). Of course, we assume that Person shall have many, many data members (and constantly increasing), so that simply defining Person::operator= (const Person& other) to handle all data except for 'name' and 'ID' is out of the question.
C++ :: Member Function Pointer Assignment?
May 15, 2013I have a class with member functions and a pointer like this:
Code:
class MyClass{
private:
typedef void(MyClass::*memFnPtr_t) ();
public:
memFnPtr_t fnptr;
void fn1();
void fn2();
};
Now in a regular function I create an instance of the class and try to assign the pointer:
Code:
MyClass mc;
mc.fnptr = &mc.fn1;
The compiler does not like it and suggests this instead:
Code:
mc.fnptr = &MyClass::fn1;
This seems to work but what if I have two instances of the class:
Code:
MyClass mc1, mc2;
How does the compiler know to distinguish between
Code:
mc1.fn1
and
Code:
mc2.fn1
when the assignment now looks identical:
Code:
mc1.fnptr = &MyClass::fn1;
mc2.fnptr = &MyClass::fn1;
C++ :: Extractor Overloading And Member Wise Assignment For Cartesian Class
Apr 6, 2014I am making a program with a Cartesian class. I want the user to be able to input 2 coordinates, but when I run it it doesn't ask for any values to be entered. It gives this output Please enter the first coordinates: Please enter the second coordinates:
(4.86129e-270, -1.97785e-41)
(4.86143e-270, -1.97785e-41)
Code:
#include <iostream>
#include <istream>
#include <ostream>
using namespace std;
[Code] ....
Also, I want to add a memberwise assignment function to assign the values of coord1 to coord2. How would I go about doing so?
C++ :: Static Variable Inside A Member Function
Jul 20, 2013Say you had:
class Foo{
public:
//...
void funky();
[Code] .....
Would each instance of Foo create a new counter variable, or would it remain the same for all of them, i.e. baz.funky() would always use the same counter variable? What if the class was a template?
C :: Using Structure In Union
May 27, 2013I'm trying to use a structure in union in the following format:
Code:
union data
{
unsigned char All[10] ;
struct data_pkt
{
unsigned char ack;
unsigned short status;
unsigned short data_length;
unsigned char Data[5];
}format;
}adb; adb.
All has 10 bytes which is equivalent to the structure bytes. ie 6 bytes if unsigned char and 2 short i.e 4 bytes. Thus total 10 bytes is given to adb.All. When I print the struct size I get 12 bytes. This creates problem in obtaining data in union. According to the program:
adb.format.ack should have the address of adb.All[0]
adb.format.status should have the address of adb.All[1]
adb.format.data_length should have the address of adb.All[3]
adb.format.Data[0] should have the address of adb.All[5]
But in actual case this is how memory is allocated:
adb.format.ack assigned to the address of adb.All[0]
adb.format.status assigned to the address of adb.All[2]
adb.format.data_length assigned to the address of adb.All[4]
adb.format.Data[0] assigned to the address of adb.All[6]
Why this is happening? How can I solve this?
C :: Set Every Array Value In Structure To Zero
Nov 22, 2013i'd like to ask if it's possible to fill every array in structure to zero. (Without using too much cycles)Something like this (I know that it doesn't work):
Code:
typedef struct {
char name[30], sname[30], adress[30], day, month; int year; char number[9], email[30];
} person;
void create_list(person z[100])
}
[code]....
C++ :: Map With Pointer And Structure
Nov 28, 2013Program to create client server interaction for store data into map using structure and pointer(without memory leak).
View 1 Replies View Related