C++ :: Static Constant Datatype For Fraction Class
Aug 4, 2013
My Fraction.h class looks like :
class Fraction {
int num;
unsigned int den;
public:
Fraction(int = 1,int =1);
//Constants of Datatype
[Code] ....
The implementation Fraction.cpp is as follows :
#include "Fraction.h"
Fraction::Fraction(int n, int d):num(n),den(d){
cout << This is double param constructor <<endl;
}
And the application main.cpp is
int main(){
Fraction f1(3,9);
f1 = Fraction::sc_fUnity; // how to implement this ?
}
How can I write the Fraction.cpp for the constant static member ?
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Apr 3, 2013
How to use static in a class, function and variable.
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Jun 6, 2013
I have designed a class called matrixType that has some overloaded operators (+, -, *, and <<); the arithmetic operator functions of which are overloaded as member functions of the class. As an alert mechanism, I want a message displayed when two matrices of dissimilar sizes are added/subtracted OR when two incompatible matrices are being multiplied. Displaying this error message is not the problem. However, I want a scheme where on detecting two matrices’ incompatibility, the operator function returns the error message (a string datatype) instead of what would be an erroneous result (the expected matrixType object).
In other words, what I may be essentially asking is: Is it possible for a function, say,
matrixType matrixType::operator+(const matrixType& otherMatrix) const
{
.
.
.
}
to return a dataType (like a string) other than the expected matrixType?
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Jun 5, 2013
I am having a problem concerning a static const member variable I want to use to set a certain property of my class during development time. The question actually concerns proper implementation as I do have a solution that "works" at least. The variable should denote the size of a member array which I don't want to allocate on the heap due to serious performance issues. So here is my code:
//MyClass.h
class MyClass{
public:
static const int MyArraySize = 256;
private:
int MyArray[MyArraySize];
};
This works but it's not nice for two reasons:
1) It doesn't separate interface from implementation. I would prefer to define the variable in the corresponding .cpp file but it doesn't work:
//MyClass.h
class MyClass{
public:
static const int MyArraySize;
[Code] .....
If I delete the line int MyArray[MyArraySize]; the above code works but when I use it to define the size of the array I get a "constant expression expected" error for the line int MyArray[MyArraySize]; which makes sense as the compiler does not know the value of MyArraySize when he reaches int MyArray[MyArraySize]; and therefore can not allocate the memory. Of course I can move MyArray to the heap like that:
//MyClass.h
class MyClass{
public:
static const int MyArraySize;
static const int MyValue;
[Code] .....
But as I mentioned before this causes a remarkable loss of performance.
Something like the following does not work:
//MyClass.h
class MyClass{
public:
static const int MyArraySize = (int) pow(2, 8);
private:
int MyArray[MyArraySize];
};
This gives a "constant expression expected" error for the line static const int MyArraySize = (int) pow(2, 8);
Interestingly the following code works:
//MyClass.h
class MyClass{
public:
static const int MyValue;
};
//MyClass.cpp
#include "MyClass.h"
const int MyClass::MyValue = (int) pow(2, 8);
So if I use pow outside of the class definition I get no errors. Is there any solution to those problems? So what I want is:
1) Don't allocate the array on the heap
2) Separate interface from implementation
3) Being able to use functions like pow to define MyArraySize
4) Not use global variables
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Jun 6, 2013
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;
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Nov 25, 2013
Write a class definition for a Fraction class. Its member fields are num and den, both of type int. The constructor builds the default fraction 1/1. It has the following operations:
void plusEquals(Fraction second);
//Adds the second fraction to this fraction like the operator += void minusEquals (Fraction second);
//Subtracts the second fraction from this fraction void timesEquals (Fraction second);
//Divides this fraction by the second fraction void dividesEquals (Fraction second);
// Divides this fraction by the second fraction void reduce();
// Reduces this fraction to lowest terms double todecimal();
//returns the decimal value of this fraction void scan(istream&);
//scans a fraction written with a slash as in ¾ void print(ostream&);
//prints a fraction using a slash Fraction();
//constructs a default fraction with denominator 1, numerator 0 Fraction(int n, int d); //constructs a fraction given value for num and den
2. Write a menu-driven driver program designed to allow thorough testing of your Fraction class.
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May 27, 2014
I'm having a problem when i convert from fraction to string. When I run my program it runs fine I'm supposed to get an output of the fraction ex (2/5) and the decimal 0.4 the problem is that it does not output the fraction all I get it / and 0.4
the code for converting from fraction to string is the following
std::string string;
char numerator[100]/* = {0}*/;
char denominator[100]/* = {0}*/;
_itoa_s(numerator_, numerator, 10);
_itoa_s(denominator_, denominator, 10);
[Code] .....
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Oct 20, 2012
I have a class that is a template, I have to declare it in my main but i want the user to choose what type of data they will use in the class, I cant just declare myclass my, i have to use myclass<int> my, how can I change so user can select the proper datatype to use in the class.
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Apr 17, 2013
From my book:
"A static function might have this prototype:
static void Afunction(int n);
A static function can be called in relation to a particular object by a statement such as the following:
aBox.Afunction(10);
The function has no access to the non-static members of aBox. The same function could also be called without reference to an object. In this case, the statement would be:
CBox::Afunction(10);
where CBox is the class name. Using the class name and the scope resolution operator tells the compiler to which class Afunction() belongs."
Why exactly cant Afunction access non-static members?
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Jul 28, 2013
I am trying to write a Fraction class and getting the following warning when compiling my code :
Fraction.cpp: In constructor 'Fraction::Fraction(double)':
Fraction.cpp:8: warning :converting to 'int' from 'double'
My Fraction.cpp class looks like :
#include "Fraction.h"
Fraction::Fraction(int n, int d):num(n),den(d) {
cout << This is double param constructor <<endl;
}
Fraction::Fraction(double d):num(d),den(0)
[Code] ....
How can I get rid of the warning ?
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Sep 25, 2013
the question am having problems with..
1.Write a class function that defines adding, subtracting, multiplying and dividing fractions by overloading standard operators for the operations.
2. Write a function member for reducing factors and overload I/O operators to input and output fractions. how would i set this up?
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Jan 7, 2014
I need an implementation for the array index operator overloading of my Fraction class . The Fraction.h looks like :
#include <iostream>
using namespace std;
class Fraction {
public:
Fraction(int = 1, int = 1);
[Code] .....
I am not able write the Array index operator overloading functions.
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Aug 22, 2014
Have following code:
class Program
{
static void Main(string[] args)
{
[Code]....
My question according to what i just wrote:
1. Is that mean that Do() is only available for use by Dog itself because Dog is 'oryginal' Dog, and if i create new dogs - instances of oryginal Dog (dog1, dog2 ...) they cant access because Do is only available fo 'oryginal' one? Is that correct thinking?
2. If i would want to have something common (e.g value) for all dogs is that good way to create static field/method for Dog instead of non-static once then all instances of Dog would access Dog static member to get/change it? Just stupid example: static method GetAmountOfLegs() which return 4 Then all instances can take/call that value from Dog. Is that correct thinking?
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Mar 15, 2015
We're assigned a project working with classes and fractions. My goal is to display a fraction in proper from based on 2 arguments passed to a class member function proper();
My strategy was to utilize the greatest common factor between the 2 arguements, then divide both the numerator and denominator by that number and then it would display.
The program actually runs, but only seems to divide the numerator and not the denominator. This in return makes my other class member functions have incorrect comparisons and sums.
Code:
#include<iostream>
#include<conio.h>
class Fraction {
friend void compare(Fraction a, Fraction b);
friend void sum(Fraction a, Fraction b);
[Code] ....
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Oct 7, 2014
How to initialize a static member of a class with template, which type is related to a nested class?
This code works (without nested class):
#include<iostream>
using namespace std;
struct B{
B(){cout<<"here"<<endl;}
};
template<typename Z>
[Code] ,....
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Dec 17, 2013
it seems everytime i use statics in a class i come across with a porblem.
this time i wanted to make a class i created static inside another class.
MainVariables.h file
static fge::window mWinMain;
if someone ever wants to reach it
MainVariables.cpp file
fge::window MainVariables::mWinMain;
...
...
fge::window MainVariables::GetWinMain()
{
return mWinMain;
}
but when i created some other MainVariables classes at other places instead of them reaching to the same window two window is being created.
yes i know maybe there are better methods but currently i m working on polymorphism and i need some static members.
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Oct 17, 2014
I've been given specific instructions to create an array inside a Class Matrix using a constant n. This is my class but I am getting errors. I thought that maybe I had to initialize the const and the array using the constructor function Matrix() instead of directly in the class, but I didn't have any luck with that either.
class Matrix
{
public:
Matrix();
private:
const int n=3;
int e[n][n];
};
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Oct 2, 2014
I 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.
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Jul 29, 2013
I wanted to add that the template argument is needed because its a "special case" but if that doesn't work what would be the next best way to solve this problem. I want to be able to declare the const size of the array outside the class far removed from it actually. I'm actually going off this page
[URL] .....
Heres the code
#include <iostream>
template <int F>
class C
{
[Code]....
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Jan 29, 2013
I wrote a template class for Matrix manipulation. The compiler cannot compile the source and complains
Matrix.h:144:41: error: expected initializer before ‘const’
What is the problem of the code enclosed below?
#ifndef MATRIX_H
#define MATRIX_H
/**
* @file Matrix.h
*The Matrix template class written for simplify the matrix manipulation.
*/
#include <cassert>
using namespace std;
template<typename T>
class Matrix {
int rows,cols;
[Code] .....
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Nov 17, 2014
I have a class containing a map member that I want to initialize at declaration time. I know I can do it in the cpp file but I'm having a problem with the order of initialization (static initialization order fiasco).
My questions are:
Is it possible that the scenario in which, the Test's constructor's implementation and the map initialization instruction are in the same cpp file and constructor is called when the map is not initialized yet, could happen?
Is it possible to initialize the map in class like I did? I get these errors:
in-class initialization of static data member 'std::map<std::basic_string<char>, Test*> Test::a' of incomplete type
temporary of non-literal type 'std::map<std::basic_string<char>, Test*>' in a constant expression
If yes, does this initialization resolve the static initialization order fiasco?
class Test {
public:
static std::map<std::string, Test*> a = {};//this is an error
Test(std::string ID) {
[Code] ....
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Jul 27, 2013
What is the purpose of having static object of the same class.
E.g.
class someObj{
public:
static someObj obj;
};
how the compiler treats this object
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Mar 14, 2014
I am developing logging class and it loos like below now, my question here is I would like to avoid situation to call this class methods multiple times in same time - as I've read when I have static class or even static method (not exactly whole class) it can be call only once in time. Is this true and whether my class would pass the concept to avoid multi accessing - lets say in case of multithreading case - if one task would try to call statuc method when there is already some other trad using it.
public static class Log {
public static string EngineName { get; set; }
private static List<String> logdata = new List<string>();
public static void LogMessage(string msg, ELogflag flag, string title = "") {
StringBuilder sb = new StringBuilder();
[code]....
And my new Enum:
enum ELogflag {
LOG,
ENGINE,
CRITICAL,
CUSTOM
}
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Oct 14, 2012
I am studying the use of static data into classes and the code below is returning an error ...
#include <iostream>
using namespace std;
class REC {
private:
static int n; //Dado que sera unico na classe e alterado por todos os objetos
[Code] .....
The error:
main.obj:-1: error: LNK2001: unresolved external symbol "private: static int REC::n" (?n@REC@@0HA)
Note: I'm using QT Creator
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Feb 20, 2015
Can distinguish between character constant and string constant giving examples
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Oct 10, 2013
If I need a static pointer to a class that is used globally(multiple files), and I only want to allocate memory once.
One way is to create a function that returns a static pointer of type class and call it where ever you need this pointer. My question is there another way to do this like with a header file and include the header file where you need to use the object of type class.
static class* function
{
static class c;
if (c == NULL)
{
c = new class;
}
return c
}
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