C/C++ :: Overloading Comparison Operators
Aug 28, 2014
I made a program that allows the user to enter information of credit cards on an array of size 5, however I need to allow the user to compare the five credit cards with each other and I am having problems with this particular part. I made my bool operator functions for the operator< and the operator> but how to make the user be able to select which cards he wants to compare and how to compare them. My code is the following:
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
const int SIZE = 5;
enum OPCIONES {CARGAR=1, ABONAR, NADA};
[Code] ......
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Oct 30, 2014
I have a small piece of code that used the set::insert function on a set of myClass. For that, I need to overload the < and > operators, which I have, but I still get a huge error saying it can't compare.
set<MyClass> mySet;
MyClass myClass
All the class information gets filled in. Then, I try to insert...
mySet.insert(myClass);
bool operator<(MyClass &lhs, MyClass &rhs) {
return lhs.name < rhs.name; //name is a string
}
The error says
...stl_function.h:230:22: error: no match for 'operator<' in '__x < __y'
MyFile.h:80:6: note: candidate is bool operator<(MyClass&, MyClass&)
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Nov 7, 2014
I have two class GameOfLife and Cell and i want to overload square braket for class GameOfLife."if g is a GameOfLife object, g[10][5] will return the Cell at row 10 and column 5. If there is no such Cells, then it will return a new Cell with position (-1000,- 1000)."
but if g[10][1000] and 1000>cols,then it returns different Cell exp (3,2) How i do control the col ( [row][col] )?
Code: vector<Cell> GameOfLife::operator [](const int row){
vector<Cell> rowCell;
for(int i=0; i<cols; ++i)
{
if( isLive(row,i) )
rowCell.push_back( Cell(row,i) );
else
rowCell.push_back( Cell(-1000,-1000) );
}
return rowCell;
}
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Nov 24, 2013
I must overload [] but at the same time I must use polymorphism. I wonder if using polymorphism affects operators overloading since when I modified the first class by writing "virtual":
virtual void mostrarDatos(char*, char*, char*);
virtual void calcularEdad(int);
So I can do the polymorphism, it affects the part of the code where suppose to do an addition:
s=student1+=student2;
t=student3+=student4;
u=s+=t;
if I do that, it shows some strange numbers instead of the right ones. Here is the complete code:
.h
#ifndef PERSON_H
#define PERSON_H
#include <iostream>
using namespace std;
class persona {
[Code] ......
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Dec 20, 2013
I build a nice class that i need the output be possible in char * and in string. But how I can do for the compiler don't be confused between them?
Code:
operator char*() {
return (char *) result.c_str();
}
These works fine. and for string, i must casting it. but i want do anotherone for string... how can i do it? I tried:
Code:
operator string() {
return result;
}
But the compiler stays confused or something
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Apr 16, 2014
S I want to have different >> operators for several derived classes. Has I tested...
Code: class base{
friend std::istream & operator>>(std::istream & in, base & v);
public:
base();
[Code]......
I noticed that the base operator is the only one being called for all 3 objects. which makes sense and now that I think about it I am more surprised that the "derived operators" compiled at all.
Still, how would I go about declaring different overloaded operators for the different classes?
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Nov 11, 2014
I am stucked in a problem of overloading arithmetic operators such as "+,*" for a class in the form
class Point {
int N; // dimension of the point
double *Pos; // length of N
}
My assign operator is :
Point& Point::operator= (const Point& pt) {
N= pt.N;
if(Pos == NULL) Pos = new double[N];
memcpy(Pos, pt.Pos, N*sizeof(double));
[Code] ....
The add operator "+" is:
Point operator+( const Point& pt1, const Point& pt2 ) {
Point ptr = Point(pt); // this is a constructor
for (int i=0; i<pt1.N; i++) ptr.Pos[i] += pt2.Pos[i];
return ptr;
}
Based on the above overloading, What I am going to do is :
P = alpha*P1 + beta*P2; // alpha and beta are double constants, P1 and P2 are Points objes
It is ok with Intel C++ 14.0 compiler, but does not work with the microsoft visual c++ 2012 compiler in debug mode in visual studio 2012.
I stepped in those operators and found that visual c++ compiler deconstructs the ptr in operators "*" and "+" before its return while intel c++ finished the operation P = alpha*P1 + beta*P2; and delete those ptrs at last.
Portability of my operator overloading is worse. How to get those arithmetic operators overloading for class with pointers in it.
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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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Feb 5, 2013
I am making a vector class and am having some problems creating the overloaded arithmetic operators and assignment operators.
Here is an example of my "+=" code as it stands the errors are similar/the same for the other operators except "=" operator which works fine:
Vector3& Vector3::operator+=(const Vector3 &rhs) {
Vector3 tmp = *this;
Set(tmp.getX() + rhs.getX(), tmp.getY() + rhs.getY(), tmp.getZ() + rhs.getZ());
return *this;
}
I have tried a lot of different approaches ad always get the error:
error: passing 'const Vector3' as 'this' argument of 'double Vector3::getX()' discards qualifiers
error: passing 'const Vector3' as 'this' argument of 'double Vector3::getY()' discards qualifiers
error: passing 'const Vector3' as 'this' argument of 'double Vector3::getZ()' discards qualifiers
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Feb 2, 2015
I need a program that can compare two xml files for equivalency using any XML Parser.
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Mar 6, 2012
I have to compare data in excel and csv based on the file name and update the status of file from CSV into excel file by creating a new column status on weekly basis.
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Jul 31, 2013
I'm making a simple game and I'm having trouble creating boundaries for the players movements. The map is a 2D vector. When I compare the vector with the players current position sometimes I get an error during run. When the error isn't occurring the behavior of the boundaries is bizarre. The error tells me that the vector is out of range.
Here is the where the map is created. It's within its own class constructor.
vector< vector<char> > map_parts;
map_parts.resize(25);
for ( int i = 0; i < 25; i++ )
{
[Code].....
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Jul 28, 2014
I have this statement - while(strcmp(x[i],"Stop")!=0); - is there anyway to compare x[i] to all the possible forms of "stop" (Stop, STOP, sTop, etc)?
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Jul 14, 2014
This is some code that simulates files and directories the same way an operating system does so. I commented out every std::string occurrence because I got the :
terminate called after throwing an instance of 'std::length_error'
what(): basic_string::_S_create
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Jan 21, 2013
I just would like to turn this into cpp:
string eg("azertyFTW");
if(eg[one of the letters contained in this string] == 'c') {
cout << "eg has the letter c in it";
} else {
cout << "not this time :(";
}
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Jan 8, 2012
so i have a std::map like this:
map<DWORD,DWORD> mymap;
now i want to sort it by the second DWORD value, and thus i have to implement my own comparison function and use sort() from <alogirthm>:
Code:
bool y(const map<DWORD,DWORD>::iterator& a, const map<DWORD,DWORD>::iterator& b)
{
if(a->second < b->second)
return 1;
else
return 0;
}
...
sort(mymap.begin(), mymap.end(),y);
...
but this throws thousands of errors at me, including C2784.
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Apr 27, 2013
bool simpleQuestion::checkAnswer(string guess) const {
for (int i=0;i<qAnswer.length();i++)
if (qAnswer==guess)
return true;
else
return false;
}
This is my code and what im trying to accomplish here is making the comparison of the two strings (qAnswer & guess) case insensitive. I know i need to loop through each character of each string and for each character i can use toupper and every char in each string will become uppercase and therefore case insensitive. However, im not sure how to go about this; if any technique used to loop through each character of the string and how to use to upper.
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Apr 21, 2013
I am trying to make a program that prints out an 8 by 8 board with 1 queen on each row.
For example, if the user enters: 0,3,4,0,0,7,6,7
the program should create following board and print:
Q.......
...Q....
....Q...
Q.......
Q.......
.......Q
......Q.
.......Q
I think I am doing it right but im getting a couple of errors that i cant fix ...
#include <iostream>
using namespace std;
int main(){
int x [8] [8], r, c;
for(c = 0; c <= 8; c++){
cout << " Enter a number from 1 to 7 " << endl;
[Code] .....
these are the errors :
assignment15_meem.cpp: In function âint main()â:
assignment15_meem.cpp:7: error: no match for âoperator>>â in âstd::cin >> x[c]â
assignment15_meem.cpp:10: error: ISO C++ forbids comparison between pointer and integer
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Jan 30, 2014
I am trying to count the number of comparisons for each of the following sorting algorithms, Selection, Insertion, Bubble, Merge, and Quick sort. This is using an array of numbers that are sorted, reversed, and randomly arranged.
I currently increment the "number of comparison" variable before every conditional statement that compares two numbers and am getting the following results:
Number of Items in Array = 100
Selection: random = 5049; reverse = 5049; sorted = 5049;
Insertion: random = 2640; reverse = 5049; sorted = 99;
Bubble: random = 9207; reverse = 9900; sorted = 99;
Merge: random = 1221; revere = 988; sorted = 1028;
Quick: random = 690; revere = 587; sorted = 636;
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May 4, 2014
template <class ST>
bool OrderedSet<ST>::IsIn (const ST & value) const {
for (LNode * np = first; np != NULL; np = np -> next)
if (np -> next == value)
return true;
return false;
}
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Dec 27, 2013
I have std::vector of players and each player have its own value. The value is of the type double, but the original value are of the "XX.00".
Now what I'm trying to do is to insert a player into this vector. For that I need to find a place and to find a place I need to compare player value.
So lets say I have a player in the vector whose value is 24.00 and I am trying to insert a player whose value is 25.00. To my surprise MSVC 2010 tells me that:
24.0000000000000 == 25.00000000000
I do aware that comparing double type is not going to work like this, but I would expect not to have such big of a difference. ;-)
Why this comparison is true and how to eliminate such thing?
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Jan 27, 2012
Why I'm getting an error here. I've dumbed down my code for simplicity and removed irrelevant code.
PHP Code:
class Foo {
public:
bool IsNull() const;
private:
std::map<int, int*> test;
[Code] ....
I'm getting a "passing...discards qualifiers" error on my if statement and not sure why because I'm not changing anything. I know removing const or making test mutable fixes the issue. I've been taught to always make a function const if it doesn't change anything, in which case, have I finally come across an acceptable time to use mutable?
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Feb 10, 2013
How to compare two files(two texts documents) and display their similarity percentage by using C++?
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Sep 15, 2014
how to put comparision condition in order to caculate total number of comparision in selection sort
static void selectsort(int[] data, int n)
{
int i, j;
for (i = 0; i < n; i++)
[Code]....
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Feb 20, 2014
So I have started this program for class but am stuck on what to do next. Basically you need to create a function to compare 2 strings (case-insensitive). The strings shouldn't be altered and the return value should be similar to strcmp.
This is my main file
#include <iostream>
//#include <cstring>
#include <iomanip>
#include "rpstrings.h"
using namespace std;
int main () {
char Str1[20], Str2[20];
short result;
[Code] .....
I don't know if I labeled the files correct. what I need to do is to add 2 defaulted arguments which will allow the user to request that you skip spaces and/or skip punctuation when doing the comparison.
Also, how I can sort the numbers when they aren't justified with leading 0's and if they aren't in the lead string (kinda of like the natural sort).
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Nov 7, 2013
So I have an insertion sort function implemented that sorts through an array, but I'm having a problem showing the correct number of comparisons to work.
Each time I'm checking a value with another, the counter should update.
For instance, having an array of 10 elements going from 10-1 should give 45 comparisons, but I'm getting 54 comparisons.
void insertionSort(int a[], int& comparisons, const int& numOfElements) {
int j, value;
for (int i = 1; i < numOfElements; i++) {
value = a[i];
for (j = i - 1; j >= 0 && a[j] > value; j--)
[Code] .....
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