this program is not giving to chance to enter the ooplevel value.
Code:
#include <iostream>
using namespace std;
const int SLEN = 30;
struct student {
char fullname[SLEN];
char hobby[SLEN];
int ooplevel;
};
// getinfo() has two arguments: a pointer to the first element of
// an array of student structures and an int representing the
[Code]...
So I have a class object that contains the private member variable spot and the public member function MoveLock. Within MoveLock, is a member variable called numbers that holds the place where a user is on a "lock knob". Now, what I'm trying to accomplish is that whenever the user turns the "knob" in the wrong direction, the position is updated with that current numbers so that the clicks needed to unlock the first state is also updated. But I get these errors:
Error E2096 C:Users...switchtest.cpp 34: Illegal structure operation in function main()
Error E2294 C:Users...switchtest.cpp 39: Structure required on left side of . or .* in function main()
Ultimately, what I have in main() is a piece of what I'm going to implement in a class member function. I'm also thinking about moving the if else statements out of the for and creating a second one for the else portion.
#include <iostream>
#include <windows.h>
#include <iomanip>
using namespace std;
HANDLE inKeys = GetStdHandle(STD_INPUT_HANDLE);
HANDLE screen = GetStdHandle(STD_OUTPUT_HANDLE);
[code]....
How can i write a function that will read an "unsigned integer" into a variable of type "unsigned short int"? i can not use cin >> inside the function.. so i am looking for atleast a hint!
View 16 Replies View RelatedI am having trouble compiling my interface. I am trying to store a reference variable as a member variable of the interface object. Compiler says that the variable has not be initiated correctly.
LCD inherits from VisualInterface which is expecting a DisplayDriver object to be passed in (DisplayDriver is another interface, but thats not important).
I pass the displayDriver object in when LCD is instantiated in maininterfaces.zip
I was pasing it before as a pointer but was told that this could cause me problems with memory leaks and a reference was better, but now I cant seem to get it to compile.
I need to keep a static variable in a member function of a class that I have many objects of. I've had some trouble with it, and when I read up I found that such variables are static across all instances. Is there any way around this?
View 3 Replies View RelatedIs it possible to initialize class member variables in their definition statement instead of using a constructor?
Is the code bellow correct?
class rectangle
{
float a=0;
float b=0;
public:
string color="Red";
...
};
Which C++ Standard allows it?
I've created a class called Voter with a private member variable ID, also I have a variable in my main function to be ID as well. I'm trying to compare the two ID's but when I do so:
if (ID == V.ID)
I get the error - 'std::string Voter::ID' is private within this context.
I know that because it's private I can't access it, but how do I?
So, one can do stuff like this using #defines:
#include <iostream>
#include <array>
#define x arr[0]
#define y arr[1]
#define z arr[2]
class Point {
[code]....
... that is, to be able to reference the same data by "member variables" as by referencing a stl container. But defines are the devil's work - adding in a "#define x arr[0]" is a dangerous statement. I'd really like some nice clean C++ method (C++11 or C++14 are just fine) to do this without defines, but so far I'm drawing a blank. If arr wasn't an STL container, if we just wanted a pointer-based array, I could do it this way:
class Point
{
...
float x __attribute__ ((aligned (sizeof(float))));
float y __attribute__ ((aligned (sizeof(float))));
float z __attribute__ ((aligned (sizeof(float))));
float*const arr = &x;
};
... but you obviously can't do that if arr is an STL container.
The best I've come up with is to make x, y, and z function pointers, but then you can't call them like p.x, you have to call them like *p.x(), it's not very clean and I'd expect some added overhead. One could go even uglier and make x, y, and z be instances of some custom class with overridden operators that reference arr[], but that seems like it'd be just getting ridiculous in terms of overhead (both coding and performance)
What is the problem with the following code is? It compiles with Visual C++ 2012 but does not with g++:
//a.h
#ifndef Loaded
#define Loaded
using namespace std;
class MyClass{
public:
static const int MyStaticValue = 200;
[Code] ....
If I try to compile this using the command
g++ a.cpp b.cpp
I get an "undefined reference to 'MyClass::MyStaticValue'" error for the line "A = MyClass::MyStaticValue;" in main(). The strange thing is that if I change the line to "A = (int) MyClass::MyStaticValue;" it works fine and the output is
200
200
as expected.
The code also compiles under g++ if I move the defintion of MyStaticValue from a.h to a.cpp by const int MyClass::MyStaticValue = 200;
I have a this program of storing students in a 2-3-4 tree. I have a template class called hw6_234tree and another class called Student. Now my private member variable (m_root) keeps being reinitialized every time I process a new line. For example the first student I run through my m_root->A = Student A...(m_root is a private variable of type Node* inside of the 2-3-4tree class).The next pass through now my m_root->A == Student B. So essentially my first run through m_root->A = Student A. Then the next run m_root->A = Student B. My question is how can I keep this variable the same and stop it from reinitializing m_root->A to student B.
Here are a few snips of the code:
Function in main:
void ProcessLine(string line, hw6_234tree<Student>& tree)
Function call:
tree.Add(Student(id, name));
Private Variable:
Node* m_root;
A function for a struct named (Node) in the private section of class hw6_234tree that assigns variables in the struct to values:
Node(T* valueForA)
{
A = valueForA;
B = C = NULL;
L = M1 = M2 = R = NULL;
}
The start of my Add function:
bool Add(T& toCopyAndAdd)
{
if (m_root == NULL)
{
m_root = new Node(&toCopyAndAdd);
return true;
}
return false;
}
I have been playing about with Vertices and Colors and have ended up with this:
template < std::size_t SIZE, typename T >
struct Pack
{
[Code].....
Is there anyway to make an alias for Pack's data field? Something that would allow me to write:
Color3f my_color;
my_color.red = 0.1f;
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 ?
Say 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?
In C++, how do i call a method member of class A from a class B, using a pointer. By the way Class A and B are of different types.
I read that when a pointer is pointing to member function it can only point member functions within the class. But how can i point to a member function outside the class.?????
for example
class A {
public:
int add(int x) {
return x+x;
[Code] .....
I have a small class and a vector to hold the objects.
Code:
class result_holder {
public:
// initialize class members
[Code]....
The purpose is to keep results and be able to sort the results on row_value while keeping the id and name values in registration with the row_value. I am running allot of tests and keeping the top n results. The idea is to sort the vector so that I can just examine the object in the last element to see if it should be replaced by a better result.
I know that this kind of thing is often done with an overloaded operator or a functor, but I am a bit out of my depth with that, especially determining what class variable will be used for the sort. sorting the above objects on the row_value variable?
I have a class that defines a window (a popup dialog of sorts), and I want the name of that window to be constant. The only problem is that the name of the popup needs to match the title of the parent window, and I get the name of the parent in the constructor. So how do I go about defining this member variable to be constant and initializing it with a value in the constructor?
I want to do something like this, but I know this isn't allowed:
/* class.h */
class foo {
public:
foo(*parentWindowPtr);
[Code] .....
I should mention that yes the name of the parent window is const char *, and I would like to keep it this way.
The question is: Define the class Counter. An instance of this class is used to count things, but the counter should never be less than 0 (non negative number). The member variable should be private. I realize what I'm suppose to be using but can't implement the member functions needed..
int main(){
int value;
cin >> value;
Counter myCounter(value);
for (int i = 1; i <= MAXLOOP; i++) {
myCounter.increment();
[Code] ....
I want define Variable that has all amount of between two integer example: 2-4
View 1 Replies View RelatedIn my program I'm trying to add 200 to the variable named "gold". I thought this would work, but I guess it's not:
int gold2=gold+200;
int gold=gold2;
Consider the below initialization of x.
int x = 0x01234567;
If x is stored in RAM as given below, what would be the address x in both case?
(if image is invisible please follow this link)
Assume that size of integer is 4 byte.
i want to store reference to a const object in my class as a member variable, as follow:
I basically want a readonly reference to |Data| in Device object.
Code:
class Device {
Device(const QList<QSharedPointer<Data>> & dataList) : _listRef(dataList) {
} protected:
const QList<QSharedPointer<Data>> & _listRef;
}
This does not allow me to initialize _listRef as something like NULL when it is not applicable.Also, i must change all my constructors and its child class to include an initialization of _listRef!!
What is the alternative? Is pointer the nearest? which of the following should be used?
Code:
const QList<QSharedPointer<Data>> * _listRef;
or
const QList<QSharedPointer<Data>> *const _listRef;
or
const QSharedPointer<QList<QSharedPointer<Data>>> _listRef; ????
I intend to reference this thread from another thread so I do not clutter that thread with code
/* This code is relied on by some of the functions I will post */
typedef unsigned long long zxumax;
typedef signed long long zxsmax;
[Code]....
I need to create a stack with the container being an unsigned int. I tried to put in numbers up to four bits each and have the program read the numbers individually. This is the code I am using:
void push(int n)//item n is pushed onto the stack, throw exception on full stack {
string str="Error";
if (isFull())
throw str;
[Code] ....
When I have tested it, the program is reading the numbers as one whole number. For example, I put in the number 2, and it displays the number 2. Then I put in 2 again, but this time it displays the number 10, instead of 2 2.
I already have the standard one that mimics the one taught in schools written but I've found that there is a faster formula that can be used however I not sure how to implement this. The formula is called the "Fast Fourier Transform", any simplistic example using this function base:
typedef unsigned int uint;
typedef unsigned char uchr;
uint umul( uint* src, uint val ) {
uint des = *src;
[Code] ....
If you're doing the buffer based functions then I have some pre-made functions you may need. [URL]
How can I use an integer variable in a http command example:
int num, canal;
for (num =0, num < 10, num++){
canal = num;
system( "wget http:'/'/192.168.3.4/channel.cgi?channel= canal");
}
On a controlled buffer of unsigned char it is possible to do subtraction faster than if you followed standard mathematical rules, here is an example:
typedef unsigned char uchr;
uchr num1 = 5; //00000101
uchr num2 = 3; //00000011
num2 = ~num2; // 11111100
++num2; // 11111101
uchr num3 = num1 + num2; // 00000010(2) - computer truncates result to fit char
Since you will be working with a buffer you don't even need to worry about truncating the final bit because the add function will not be able to reach it - unless it is given the ability to grow the buffer in which case you just set the bit to 0 yourself
