I've got some problems with the declaration of a bitset container in my class
I've got a class A and want to have a bitset container in it, whose size just get's defined when running an instance of this class:
#include <bitset>
class A {
bitset <n> bc;
A(int n) : n(n) {};
};
Something like that.
I am looking to have a member of type bitset in a C++ class. Is it possible ?
Something like below:
Class abc
{
bitset<32> var;
}
#include<iostream>
#include<conio.h>
#include<string>
using namespace std;
class ir;
class Bank_acc {
private:
string name,type,s;
long int accno,temp,balance,in;
[Code]....
errors are:
|6|error: forward declaration of 'class ir'|
|54|error: invalid use of incomplete type 'class ir'|
|99|error: no matching function for call to 'ir::interest()'|
I have a class "SelectionGroup" which derives from a class "RMFObjectContainer". RMFObjectContainer has member variables of type SelectionGroup, so I need to include SelectionGroup.h in the header of RMFObjectContainer.h.
However, since SelectionGroup needs RMFObjectContainer to derive from it, I get a typical case of mutual inclusion.
I then proceeded to put the forward declaration
class RMFObjectContainer;
instead of
#include "RMFObjectContainer.h"
into the header of SelectionGroup.h.
However, I receive the following compile error (MSVC2010), as if the forward declaration was unseen:
#pragma once
#include "Solid.h"
#include "Entity.h"
#include "SelectionGroup.h"
[Code]....
In the code given below using turboc++ 3.0(really old i get it but its school rules)
#ifndef emoji_h
#define emoji_h
class emoji//here for some reason {
};
#endif
error i get :line 3 declaration syntax error why and how to correct it?
i want to assign number of bits by a variable in bitset? how to do that? like bitset<4> foo; instead of 4 i want to use some variable and later on by user i want to assign it! boost library or any other library!
View 1 Replies View RelatedI am designing an application in which I need to deal with many different variables in which different sequences of bits are stored. I have very strict memory requirements so I decided to use the boost::dynamic_bitset data type which works very well in my scenario as I need to dynamically allocate/deallocate/resize the variables.
The only problem is that I am not able to change the size of the blocks in which the dynamic_bitsets are stored.
I mean, even if I specify the blocks should be "unsigned char", I always obtain 32 bytes allocation by sizeof function, even if the variable is empty.
I am writing a code using Visual C++ to access serial port.
Code:
HANDLE hSerial= CreateFile(L"COM1", GENERIC_READ | GENERIC_WRITE,0,0,OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL,0);
DCB dcb = {0};
dcb.DCBlength=sizeof(dcbSerialParams);
dcb.BaudRate=CBR_1200;
dcb.ByteSize=8;
dcb.StopBits=ONESTOPBIT;
dcb.Parity=NOPARITY;
I am getting error in all last five lines in above code at dcb. and error is give below:-
Error: this declaration has no storage class or type specifier
I am just learning using class template but I keep getting error unable to match function definition to an existing declaration
template <typename T>
class Homework {
private:
string name;
public:
template <typename T>
void SetName(T val);
[Code] ....
I am trying to make a menu program and was wondering if there is a way to declare something more than once without using a different word.
ex.
#include <iostream>
using namespace std;
double grams, ounces, inches, feet, meters; //units to convert
int choice; //menu choice
int main() {
cout << "Welcome to Measurement Converter" << endl;
[Code] .....
I dont really know how to explain it but im trying to use int choice to make choose a program from a simple list.
I would like to know the difference between the following two forms of array declaration:
(1)double myArray[3] = {1.0, 2.0, 3.0};
(2)array<double,3> myArray = {1.0, 2.0, 3.0};
If I say the second one allows to use different functions like .begin(), am I right? Is there any other difference between these two declaration?
Can we use using declaration within name space scope? is it safe to use it?
I think we can use using declaration for class scope and function scope only.
I am trying to understand the behavior of following code. Basically how does printf() prints the value rather than address.
Does initializing value to a pointer during declaration makes a difference when assigned from a variable?
Code:
1 #include <stdio.h>
2
3 int main() {
4 const char *var1 = 'A';
5 int *vint = 10;
[Code] ....
I read that Memory is allocated during definition of a variable and not during declaration. Declaration is something like,
Code: int x;
And definition is assigning some value to it. This is what my professor taught. My doubt is if memory is not allocated during declaration, then how the compiler successfully compiles and runs the following, which i had already tried.
Code:
#include<stdio.h>
#include<conio.h>
int main() {
int c;
int *p=&c;
printf("%x",p);
getch();
return 0;
}
The variable c is only declared. But the program outputs a memory address. Shouldn't it show an error?
I've included <cstddef> into a project of mine in favour of <stddef.h>. When I tried to compile my project, I get 50+ errors stating that types such as "::size_t", "::div_t" and "::abort( )" have not been declared even though <cstddef> includes <stddef.h>.
I've tried searching both the global namespace and the standard namespace, but neither way works. At this moment in time, I don't have any compiler options enabled that may affect the way identifiers are defined, C++11 isn't enabled (which doesn't affect the <cstddef> header anyway), the project is a C++ project, and I've tried using the plain old <stddef.h> header, but the problems still persist.
I'm using GNU's C++ compiler ("__GNUG__" is defined).
What is the difference between:
const int testFunction() &
int testFunction() const
I have recently found this article: URL.....In their example, by declaring variables in other order, they saved 8 bytes. However, shouldn't compiler take care of it? Is it true, and should I declare variables more carefully?
View 3 Replies View RelatedIf i declare 2 variables like this static int first, second; will both of them be declared static or will only first be declared static and second a regular variable?
View 5 Replies View RelatedI want to understand the ways in which arrays can be declared and used. What each of the following do or what's the difference between them and what would be the length of each:-
1 - char ary1[50];
2 - char ary2[50] = {'H','e','l','l','o'};
3 - char ary3[50] = {'H','e','l','l','o',' '};
4 - char ary4[50] = {' '};
5 - char ary5[50] = {' ','H','e','l','l','o'};
6 - char ary6[50] = {' ','H','e','l','l','o',' '};
Code:
struct foo {
char label[64];
int state;
} bar[3] = { };
Will the above code ALWAYS initialize to 0 all objects:
bar[0].label
bar[0].state
bar[1].label
bar[1].state
bar[2].label
bar[2].state
Using gcc and g++, it does in my testing But was wondering if it can be unsafe under some circumstances.
I even tried without = { } and it is still initialized to 0 for all objects!
I want to access the body of the Add() of a list in c# to see how it works, but it only just gives me the declaration.
[DebuggerTypeProxy(typeof (Mscorlib_CollectionDebugView<>))]
[DebuggerDisplay("Count = {Count}")]
[Serializable]
public class List<T> : IList<T>, ICollection<T>, IList, ICollection, IReadOnlyList<T>, IReadOnlyCollection<T>, IEnumerable<T>, IEnumerable {
public void Add(T item); // thats all. I tried go to declaration but still gives me this line of code. This is from metadata in Visual studio.
}
How this thing work. It just a declaration not a definition yet its still doing something. How is that possible.
is possible to combine structures declaration and definition in programming language?
View 3 Replies View RelatedAny difference between
Code:
class SomeOtherClass;
void foo(SomeOtherClass* p);
And
Code:
void foo(class SomeOtherClass* p);
I was told that "2" would limit the scope of the forward declaration to the declaration of foo... However, after testing it, it appears that both behave the same...
I keep getting a "Declaration syntax error" at line ""int main()". Is there something wrong with my int main()? And how do I go about it? Here is the program:
#include<stdlib.h>
#include<iostream.h>
#include<stdio.h>
#include<math.h>
#include<conio.h>
float rung4(float x, float y, float h)
int main() {
float eps=0.00001;
[Code] .....
I would like to write a program that prompts the user to enter a series of client names which the program will then store in an array of structures. I'm thinking something along the lines of:
struct sInfo {
vector<string> vName;
float fClientHoldings;
};
sInfo sClientData[100]; //create an array of structures for up to 100 client's
sClientData[0].vName="Acme"; //these will be inputted by the user in my program, but I've attempted to initialize them here for simplification
sClientData[1].vName="Enron";
I can't declare a structure array after I declare it. Is this true? If so, is there an alternate approach that I should be using?
I have a little program that does some statistical processing on text files. The program has thrown a segmentation fault with an input file that is larger that I have used before. I didn't write this tool, so I went searching for the problem. Data from the input file is dumped into a 2D array and the program fails at the declaration of that array.
Code : double A[cont][Nr_col_split];
The vales for cont and Nr_col_split and determined from the input file and in this case, cont=807 and Nr_col_split=350. I assume that these values are just too large and not enough memory can be allocated, or something like that. Do I need to use reserve or similar to set aside enough memory? I will have input files that are quite a bit bigger than this one, so perhaps there needs to be a different solution for storing the input file data.