To get a value I would always use setter and getter. Would it be much better (performance) to use vector subscript operator overloading? And does vector subscription operator overloading require a size for the vector?
vector<int> v(10);
because otherwise, it doesn't work...
I'm trying to implement a vector class in C + +. However when I go to actually run the main, it generates an interrupt operating system.
MAIN.cpp
#include "header.h"
int main() {
// Definisco le istanze delle classi
vettore <int> vet;
vettore <int> vet2;
vettore <int> vet3;
[code].....
I keep getting this "Debug Assertion Failed" error that says:
expression: vector subscript out of range
I tried to make the loop the same as the vector size, but I'm still getting the same errors.
void Grid::output(ostream & out) {
vector<vector<int>> grid(4);
int rows, columns;
out << " 0 1 2 3 " << endl;
out << " +---------+" << endl;
for( rows=0; rows<grid.size(); ++rows ) // make each row
[code]....
When i build this program i get no errors, however a message appears saying vector subscript out of range. What does this mean and what can i do to mkae my program work
#include <iostream>
#include <ctime>
#include <cstdlib>
#include <iomanip>
#include <cstring>
#include <time.h>
#include <vector>
using namespace std;
[Code] .....
I will try my best to describe this problem I am having because I am not sure if I can reproduce the error in a small code example as this is part of a large code project.
I have a plain std::vector which contains pointers to objects.
When attempting to delete the objects, even if I know for a fact that the std::vector has at least one object in it as shown by the debugger, I get the "Vector Subscript Out of Range" error.
I'll even do a range for loop like so:
for (auto & e : CurrentObjects) {
delete e;
}
And yet I still get the "Vector Subscript Out of Range" error. The destructor is never called for the object represented by "e" so I am not sure why I get the error.
I have the following code. however, when I debug it gives an error saying" vector subscript out of range"
Vector based mufti-dimensional arrays
Vectors are a STL container that allow you to store pretty much anything in them. When used correctly they can be very powerful containers.
They provide an added benefit that they will automatically remove the memory they use when they go out of scope. This means that objects stored within a vector do not need to be de-allocated (but pointers to objects do). You can also do some interesting things with dynamic multidimensional arrays with vectors.
For example, if you only allocate the first dimension, then use the .push_back() to add records to the 2nd dimension it's no longer a grid, but an array with a dynamically sized 2nd dimension (much like a street of buildings each with a different amount of floors).
This functionality can be achieved using pointers, but is much harder to do.
#include <iostream>
#include <vector>
#include<conio.h>
using std::vector;
using namespace std;
[code]...
In this below example:
class Point {
private:
double m_dX, m_dY, m_dZ;
[code].....
In that situation, << does not call the overloaded function, but rather calls the << method defined in the i/o library, which prints a message to the controlling terminal. So once it prints the message to the terminal, it then returns the out instance. Why return the out instance rather than a boolean like true? As you can see from the example, once the message is printed to terminal, out is not used anymore.
My project's goal is to read some numbers from input file,then create a grid.my input file is:
2 3
3 4 5
1 2 4
first line is rows and colums. second and third line the grid location values.My code is
#include <iostream>
#include <fstream>
#include <cstdlib>
#include <string>
#include<vector>
using namespace std;
[code].....
I am working on this assignment...
Code:
#include <iostream>#include <iomanip>
using namespace std;
class Score
{
private:
// Value at which we'll shift digits from million_counter to billion_counter
static const int THRESHOLD = 1000000000;
[Code] ....
It gives the errors:
line 105 error: million_counter was not declared in this scope
line 106 error: normalizeScore was not declared in this scope
line 110 error: million_counter was not declared in this scope
and more of that until
line 170 error: no match for 'operator<<' in 'std:perator<< <std::char_traits<char> >((* & std::cout), ((const char*)"a+b is ")) <<operator+((*c(const Score*) (& a)), (*(const Score*)(& b)))'
I thought that because i declared friend functions, they would be able to access the private variables of the class.
Well... I observed, as a non-professional programmer that "overloading operators" has some strict rules and some conventions... so any operator can differ from another. In order to have a clearest idea, I'd like to ask you to specify, for every operator, the correct (or best) way to overload it.
There are cases where you define &operator and cases where you define operator (without "&"). There are cases where operator are defined as "friend" inside class, and other cases where operator is declared externally.
example: ostream &operator<<
(why it uses & ??)
So can we have a summary for all kind of operators?
I'm trying to overload operator<<, but I get an error saying 'ostream' does not name a type. Am I forgetting to declare something else? ostream& operator<< (ostream& out, Struct &b);I made sure to #include <iostream> too.
View 1 Replies View RelatedI am having a bit of an issue figuring out how to operator overload with chaining. I have this as my operator= function (Its for linked lists)
WORD & WORD::operator=(const WORD & Org){
cout << "
operator= has been called WITH CHAINING
";
character *p = front;
[Code] ....
I want to be able to do X = X = X where X is of class WORD, but it errors when that line is called. And by error, I dont mean a written error, it just compiles, then says 'MSVC has stopped working' on a new pop up.
I want to implement operator overloading for +=, so that the following arethmetic is possible for matrices: matrix += matrix
Here is how I have defined it in matrix.h
#ifndef MATRIX_H
#define MATRIX_H
#include <cassert>
#include <iostream>
#include <iomanip>
using namespace std;
template <class T> class Matrix;
template <class T> Matrix<T> operator+= (const Matrix<T>& m1, const Matrix<T>& m2);
[code].....
How do I implement this correctly?
How to finish these two remaining operator overloading functions
Also, "contents and NumItems are private"
Code:
Bag operator+ (const Bag& b1, const Bag& b2);
//Postcondition: the bag returned is the union of b1 and b2.
ostream& operator<<(ostream&, const Bag&);
//Overloading operator <<
[Code] .....
I have a date class and i overloaded operator >> to accept input in dd/mm/yyyy format. if i enter the wrong date format my program will crash. How do i do exception handling for this? How should i do the try part? and for catch, I'll just catch a date class variable?
Code:
void operator >> (istream &is, clsDate &date) {
string inputDate;
is >> inputDate;
int mm = stringToNumber(inputDate.substr(3,2)); // read 2 characters from character number 3 start
int dd = stringToNumber(inputDate.substr(0,2)); // read 2 characters from character number 0 start
int yy = stringToNumber(inputDate.substr(6,4)); // read 4 characters from character number 6 start
[Code] .....
i have 1 nice write() function:
void write() {
cout <<"";
}
template <typename A, typename ...B>
void write(A argHead, B... argTail) {
cout << argHead;
write(argTail...);
}
these function works. but if i concat literal strings with '+', i must use '(string)'. so i'm trying overload the operator + for concat literal strings, but without sucess:(
string operator + ( char *value1) {
string value2;
value2=(string) value2+value1;
return value2;
}
(these functions are inside of my Console class)
What is the role of friend function in this program? Is it even executed here?
#include <iostream>
using namespace std;
class loc {
int longitude, latitude;
public:
loc() {} // needed to construct temporaries
[Code] ....
I have a class A, from which three classes Aa Ab and Ac are inherited. In class A I have defined some functions by virtual foo()=0, which I implemented in each subclass. Each class is written in a separated .h and .cpp file.
However, now I think it is possible to overload the operator+ INSIDE each class (including pure virtual in class A), such that something like
int main() {
A *value = new Aa();
A value2 = *value + 1.0f;
}
This should be realizable, because the operator+ is part of the Aa class. Now, I would like to do something like
int main() {
A *value = new Aa();
A value2 = 1.0f + *value;
}
This time, I expect I cannot overwrite the operator+, because it is not part of either class A or class Aa.
1st Question: I have three different classes A, B, and C; and correspondingly overloaded the insertion stream operator(<<) for all three classes. Classes A and B each have objects of class C as private data members. I am seeking a scheme whereby the << operator behaves differently for class C objects when an object of class A is to be printed from when an object of class B is to be printed. In other words, I want to have one << operator function invoked for class C when the object in question is of class A and another << operator function called for class C when the object in question is of class B. Is this realizable?
2nd Question: I have a derived class that uses a search function defined in an 'inaccessible' linked-list base class. By inaccessible, I mean I cannot change the contents of any of the member functions of this base class. The search function has three cout statements that print string literals showing results of the search operation if:
a. list is empty
b. search item is found in the list
c. search item is not found in the list upon searching
I am seeking a scheme whereby, instead of displaying the results of the search operation on the standard output (i.e. screen), a function I write can capture these string literals as input parameters, and process them for a Boolean value return. Is it possible to preclude the printing of the literals on the screen in this manner?
I have a class:
class Foo {
private:
MyType* things[10];
};
While I would like to overload the [] operator for the use as this:
Foo myFoo;
myFoo[0] = myFoo[1];
Right now I am getting ugly:
MyType** operator[](size_t idx) { return &(things[idx]);
//...
*(myFoo[0]) = *(myFoo[1]);
Anything to fix that up a little?
I wrote a class that can display fractions ex. 1/4 and I cannot figure out how to get >> to process 1/4 and separate them into variables numerator and denominator.
my program just constantly creates RationalNumber Objects when it reaches cin >> A .
my overloaded stream extraction function:
istream& operator >> (istream& in, const RationalNumber& rn)
{
char L;
[Code].....
I have a program written to add 2 complex numbers. Everything is working, except when the sum gets written, it gives me a number that is way off.
#include <iostream>
#include <complex>
#include <fstream>
#include <cstdlib>
#include <math.h>
class complex {
public:
complex();
complex(double r, double i){
[Code] .....
And my output ends up being Enter a complex number (a+bi) :
1+2i
Enter a complex number (a+bi) :
2+3i
x 1+2i
y 2+3i
4.8784e-270+4.85593e-270i
I'm working on a project and I'm not quite sure how to implement the Copy constructor and Overloaded assignment operator.
This is what the instructions say if that matters at all: Since you have dynamic variables in your class, you should make sure that the big three are implements. You already have the destructor, but you will need to add a copy constructor and the overloaded assignment operator. This is simpler than it sounds, but it requires some thinking. You need to make sure that both the copy constructor and the assignment operator create new containers.
Here is my header file:
#ifndef CANDIDATELIST_H
#define CANDIDATELIST_H
#include "CandidateType.h"
#include <iostream>
[Code].....
I know I don't have much in these functions but I'm not sure how to apply them or if I'm even headed in the right direction.
#include <iostream>
using namespace std;
class Date {
private:
int month, day, year;
public:
// class constructors can be overloaded
Date(int m, int d, int y) {
[Code] ....
Actually ,I'm not sure whether my understanding of operator>> function is correct. Here is my understanding of operator>> function.....
operator>> function takes Date object as argument from main function and it reads data from the console using istream(This is all I know about istream) into the new Date object which is created by operator>> function..
This is all I know about operator>> function...I really don't know why it has to return istream reference(I know the return type is istream, but other than that ? I want to know why operator>> function creates new Date object ? It already has a reference to Date object ....why not simply set the values of the already existing Date object instead of creating one..?
Can an overloaded operator be a friend function?
View 7 Replies View RelatedSo i am having troubles with operator overloading in inherited class. Basically, it doesnt work. Consider this:
Code:
class A {
public:
A() {
x=0;
z= new int;
[Code] ....
Some how the copy constructor of a is improperly executed - the pointer is copied over, not re-created. As a result, the destructors crashes due to double-free.
*/
B bb = b; //doesnt work
B bbb(b); //doesnt work
B bbbb(b, 0); //works
}
Above code shows the problem well. The "official" copy-constructor wont work - it copies over the pointer directly, and doesnt create a new one as it should. However, if i provide my own pseudo-copy-constructor that works. But ofcourse it's just a cheap work around - and wont actually work in real code (STL).
compiler is VS2008SP1.