I 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] ....
I'm trying to assign a value to a member of a struct that I called via an overloaded [] operator. I have the following code for the struct:
typedef struct {
float r, g, b, a;
float operator [](int pos) {
switch (pos) {
[Code] ....
And what I wish to do is
MyStruct a;
a[0] = 0.5;
Is it possible with a struct? How to express this to search engines so I haven't been able to find anything about it. If this is not possible with a struct, is there a way to define something that can do all the following things:
SomeStruct test = {0.5, 0.5, 0.5, 1};
test.g = 1.0;
test[0] = 0.0; // test[0] would be equivalent to calling test.r
float somevalue = test[3]; // test[3] would be equivalent to calling test.a
I hope I've been sufficiently clear.
This 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 ?
Why 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 ??...
Is it possible to assign a value to structure member inside the structure.like.....
struct control{
char tbi:2 =0;
char res:1 =0;
};
I am reading the book C Programming Language. On Structures, it says:
"The only legal operations on a structure are copying it or assigning to it as a unit, taking its address with &, and accessing its members."
What does it mean assigning a structure as a unit?
I'm trying to assign a value to the variables in my struct using the statement:
fscanf(fp, "%s%10s%9s%s", acct.name, acct.num, acct.pin, strbal)
but when I try to access them, it looks like the variables (acct.name, acct.num, acct.pin) are all empty.
Code:
#include <stdio.h>
#include <stdlib.h>
#define MAXAMT 999999.99
[Code].....
Well I tried to assign a new char value from a struct to another char variable but I got the "Cannot convert 'int' to 'char'" error when compiling. I've tried several alternations but I still can't get away with this error.
Here's a section of the code:
javascript:tx('code')
for(int i = 0 ; i < 10 ; i++){
pts[i].dist = sqrt((pts[i].x*pts[i].x)+(pts[i].y*pts[i].y));
}
[Code].....
"
#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.
I 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?
See 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";
}
is 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?
template <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
I was looking at some linked list material and was wondering something. Can you initialize a data member inside a struct like in C++? i.e.
Code:
typedef struct node
{
int data;
struct node * next = NULL; // this is the line in question
} LLnode;
I'm a C beginner trying to assign struct member values to other struct members to create a list.
I've tried dot notation, pointer notation, strcpy, memcpy, memmove and normal assignment.
Nothing has worked.
cust_list.h
Here's the definition of my struct:
struct Speaker {
static int numElem;
string name;
int number; // Phone
string topic;
float fee;
};
// IN main() FUNCTION
Speaker s[10];
The goal is for numElem to keep track of how many of the 10 elements are in use. However, I'm not sure the proper way to access the element, if it's even possible.
The program I'm working on is a very basic relational database. I've isolated my problem for simplicity. I get a segfault right here when I try to access db->relationCount. I tried printing db->relationCount from within loadDB and that worked,
[code]
loadDB(db, configFile);
printf("%d",db->relationCount);
fflush(stdout);
I am trying to create a class type structure using struct instead of classes.
Code:
#include <iostream>
#include <stdlib.h>
using namespace std;
struct myclass {
int * array;
int nelements;
[Code] ....
Guess what I am asking is using the pointer in the first code section better or is there another way'. I don't know about making the second code work.
How to get relative memory address of members of Class or Structure ? I want to auto scan the members of Class/Struct, and show the address/value like the "watch window" in debug mode of popular C/C++ IDE software.
View 2 Replies View RelatedI would like to have a unmodifiable standard of WAVEFORMATEX defined as a member of a class of mine. Something like:
class InputTest {
public:
const WAVEFORMATEX StandardWaveFormat;
public:
void TakeInput(WAVEFORMATEX pFormat);
};
Then in my cpp file to hard-code the values:
WAVEFORMATEX InputTest::StandardWaveFormat {
//Instantiate WaveFormat -- PCM standards
StandardWaveFormat.wFormatTag = WAVE_FORMAT_PCM;
StandardWaveFormat.cbSize = 0; //extra information sent over stream. Usually ignored in PCM format.
[Code] ....
I get the following errors starting with the header file:
Error1error C2146: syntax error : missing ';' before identifier 'StandardWaveFormat'
Error2error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
both associated with the "const WAVEFORMATEX StandardWaveFormat; " line.
Here's a link to the WAVEFORMATEX struct: [URL] .....
Then the cpp source code is probably way off. Let me know if you'd like to see the errors associated with that.
I 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].....
I 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?
I work on a system that communicates with other systems via messages. Those messages are defined in a spec and every word must be exactly as defined. To accomplish this Ada allows me to define the fields of my record to specific words in memory.
Code:
word = 4;
type Msg_Type1 is record
x: Some_Type;
y: Another_Type;
z: Another_Type;
end record;
[Code] ....
I 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] .....
#include <stdio.h>
#define MAX_USERS 20
struct {
char ID[10];
char Name[40];
int Pos;
[Code] .....
I was attempting something weired with address to move data around when I discovered that the size of the array is not what I expected. I am passing this structure as &Users to a function that declares it as a void *, then I can deal with chunks of data (memmove) and not have to worry about index or things like that. However...sizeof is returning something I do not understand.
I get the following error in XCode whenever I try to access the member I created 'randomGen' in a separate class in a different header file. I have made sure to include the header file and have tried to access it through an object.
This is the code I enter when trying to access the method from randomiser.h in main.cpp. It is also an overloaded function with doubles and integers:
RandomG randomiser;
randomiser.randomGen(); // 'Call to member function 'randomGen' is ambiguous'
This is the code inside randomiser.h:
#include <string>
#include <iostream>
using std::string;
using std::cout;
using std::endl;
class RandomG {
[Code] ....
This is the error inside xcode: [URL] ....
I have tried seperating the code for the functions in another class (main.cpp) and then running and it seems to works, so I'm not sure why I can't put everything in the .h file and then access it?
I would like it in a seperate file so it doesn't clutter my main. I am writing a game with SDL so that might be confusing and I would like the window to have a random title and other random properties, so it would be easier to use a function.