C++ :: Returning Datatype Other Than The Declared Function Header Datatype
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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Nov 27, 2013
I have made a new data type which named LongDouble
it takes 16 byte to save the number
the first bit for the sign
the next 15 bit for the exponent
the other 112 bit for the mantissa
I have to apply four operation on these numbers , but i have a problem in addition , when the sign for any of the numbers is negative ,how i can perform the operation , also if there is a Mantissa how i can also perform the operation?
if i try to save mantissa in a variable there would a loss of precision ... Here's my code
LongDouble LongDouble::operator+(const LongDouble& olong) {
LongDouble temp;
if (this->sign == 0 && olong.sign == 0) {
temp.exponent = this->exponent + olong.exponent;
[Code] .....
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Nov 30, 2014
I just wanted to know a way to cut off any remaining zeroes from a double data type. I' trying to calculate cost and output it but it keeps adding a bunch of zeroes on the end. I know there must be a way to
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Mar 31, 2013
the compiler doesnt accept void functions used with threads (for the first time and all of sudden!?)
#include <cstdlib>
#include <thread>
#include <windows.h>
[Code]....
this is a sigment of my code. Compiler says that the error occurs in line 47 (marked by ***). Leaving out the braces makes it even worse.
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Nov 11, 2014
My code:
#include<cstdio>
#include<iostream>
using namespace std;
main() {
long double j;
scanf("%Lf", &j);
cout<< j;
return 0;
}
If I give any number as input, the output is always 0. why? where's the problem ? p
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Feb 28, 2013
coming from Java, my experience with the Classes in C++ is quite limited.
Thats why I am having trouble converting the following (simple!) Java-Program.
Most examples with linked lists I found on the web describe how to implement the LinkedList class itself. But my problem is different: I want to use such a Class (I have a LinkedList class available on my system which is presumably OK).
Code: package main;
import java.util.ArrayList;
public class Main {
public static void main(String[] args) {
BoxList<String> sl = new BoxList<String>(
new ArrayList<ABox<String>>());
sl.getList().add(
new BoxPair2<String>(new BoxPair2<String>(
[code].....
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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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Aug 11, 2014
How you would overload an operator for Common Data-types like "char" and "int".
I often use bool arrays to create a multilevel-trigger-systems, when iterating over multiple containers or waiting for two events to occur at the same time.
For example:
I would define..
bool trigger[2] = {0, 0};
And when doing work via a loop, I use it like so:
while(trigger[0] != 1 && trigger[1] != 1)
You can probably see where I'm going with this. I want to be able to use my bool array with the "!" operator.
So if "trigger == 0" (as a whole), it returns false.
How can I achieve this?
Can you create custom operators? Say if I wanted to create "or-gates" or "xor-gates" etc.
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Apr 3, 2013
How to use static in a class, function and variable.
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Mar 16, 2013
I am need to compare 2 items from 2 separate drop down lists. These values are of int type. Say for example 2 drop down lists showing years. Now i need to find out these 2 years selected is greater or nearer to the current year.
I tried converting the values i receive from the drop down lists to int variables. But i am getting error then. I gave it like below.
int tmp = Convert.ToInt32(ddl_1.SelectedItem.Text);
this gives an error like this - Input string was not in correct format.
I need to know how to put an item from a drop down list to a variable of int data type.
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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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Dec 20, 2014
I have the codes for such a problem where, to create a program that counts how many times the second string appears on the first string. Yes it counts if you put 1 letter only, but if you put 2, it is an error. As an example. If the first string is Harry Partear, and the second string is ar, it must count as 3. Here's the code:
Code:
#include <iostream>
#include <conio.h>
using namespace std;
int main ()
[Code] ....
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Feb 10, 2015
I have a header file that declares some fields as private, I then have a class that I need to compare two of the objects' information for equality but neither of them are the calling objects. I cannot alter the header file. How would I go about comparing private data fields? I will enter a brief bit of code for clarity.
Code: // Header File
// stuff.h
class stuff
{
private:
int* arr[20];
int size;
};
bool equal (const stuff& a, const stuff& b);
[code].....
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Mar 4, 2014
I need writing my header files for my program of hangman. I've written what I could, but when I try parts out on their own to see if they work, I get errors. I haven't written my driver yet since I wanted to get this header working first. The first function needs to take the name of the file and read in its contents into the globally declared array. The second function takes no arguments and returns a word from the word list chosen at random. I guess my question is, would what I have so far work, or am I completely off? Here's what I have so:
randword.h
#ifndef _randword_h
#define _randword_h
//static char words[100][50];
/*
*Function: InitDictionary
*This function reads in the dictionary of words and puts them into an array. */
void InitDictionary(void);
[Code] ....
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Apr 1, 2014
I am currently doing the assignment about linked list. Here are some details information about what I am doing.. This program is C++ and should run on Visual Studio 2010. And it contains three file, two datastructure header and one main cpp file.
This program is trying to arrange and show some sports records. The main program which contain the functions such as reading the result text file(each result text file contain several records of athletes), removing a file, arranging the totalresult and printing it out. And the main program is already given and I cannot overwrite it.
But when I finished and try to build the solution and run it, I am not able to run the program and it give me somethings like these...
warning C4172: returning address of local variable or temporary
error C2248: 'Datastructure1::Datastructure1' : cannot access private member declared in class 'Datastructure1'
see declaration of 'Datastructure1::Datastructure1'
see declaration of 'Datastructure1'
This diagnostic occurred in the compiler generated function 'Result::Result(const Result &)'
And I have tried to comment each function part of the header file and see if can run or not. But I still fail to do so. Here are my codes...
#ifndef DATASTRUCTURE1_H
#define DATASTRUCTURE1_H
class Datastructure1 {
Public:
Datastructure1( );
[Code] ....
There are two header files and look quite long. They are all some linked list functions . I have read and learn linked list data structure before I complete this programs. However, when I complete the functions required, the function cannot be compile....
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May 16, 2014
I'm doing a compiler, and I'm using writing everything in headerfiles.
at the moment I have lexer.h, token.h and for this case I need reservedWords.h
reservedWords.h is made up of enums showing the needed words
in token.h I have a function called reservedWords reservedLookup(string str) which returns a reservedWord (enum)
now in lexer.h I have a function called Token* getNextToken() in which I need to make use of the function reservedLookup found in token.h
note that all of them are classes apart from reservedwords as in
class Lexer
{
public: .....
}
class token
{
public .....
}
how I can call that function?
I tried declaring reservedWords reservedLookup (string str) BUT obviously it's directing me as Lexer::reservedLookup and not as Token::reservedLookup
When I tried using Token::reservedLookup it gave me
E:Universitycompilerslexer.h|65|error: cannot declare member function 'Token::reservedLookup' within 'Lexer'|
N.B I use namespace std, that's why I didnot write std::string str
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Aug 20, 2013
MCLoad.h - MCLoad.cpp
bool MCLoad::Load(SDL_Surface* Name, std::string File){
Name = NULL;
Name = SDL_LoadBMP(File.c_str());
if(Name == NULL){return false;}
else{return true;
[code].....
compiler gives me the error bg was not declared in this scope. i googled it.
in MCInit #include <SDL/SDL.h> #include "MCLoad.h"
in MCLoad #include <SDL/SDL.h> #include <string>
in MCClean #include <SDL/SDL.h> #include "MC.h"
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Jan 30, 2013
struct x
{
y *GetY(); //error: what is "y"?
struct y
{
};
};
Why does GetY have to be declared after struct y is declared? I thought order of class members in C++ did not matter? Does it have to do with the way parsing is done?
EDIT: It also doesn't work if I typename x::y *GetY();, which makes even less sense to me.
EDIT: It works if I forward declare, but this goes against everything I know about C++ classes...
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Mar 6, 2015
I have seen functions that declare arrays in the function input even thou the arrays is already declared in main. Why do you do this?
For example:
int ova(int antal, char glosorSv[][MAX], char glosorEn[][MAX])
int main(void)
char glosorSv[][MAX]
char glosorEn[][MAX]
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Apr 20, 2013
I have this code:
const BYTE original[2][4] = {
{0x00, 0x00, 0x00, 0x00},
{0xFF, 0xFF, 0xFF, 0xFF}
};
void function(const BYTE** values){
[Code] ....
You might notice that the above code doesn't compile, this is the error:
cannot convert parameter 2 from 'BYTE [2][4]' to 'BYTE *'
1>
Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast
Even after some search I couldn't really find an answer to my problem, how do I pass the const BYTE array which I declared above in the function as a parameter (or what structure do I need to set for the function as a parameter)?
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Feb 20, 2015
I am making a game commonly know as the Hangman using C++.
Now I am trying to add a man in it like this:
0
|/
|
/
Now the problem i am facing is that i am using a check that if a function returns the value 0 "return 0" it means the guess is wrong and it will not update the man but if it returns any value there will be a function called which will update the man.
I just wanna know that how i am going to use the check, the kind of thing that i am trying to use is, in general words "if(function returns a value) then update the man"
int main() {
return match;
}
How are we going to use it in check that if int main is returning 'match' in the check...
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Jan 22, 2014
This simple little program is not returning a value. The output is
" (string) contains characters" (The number of characters is supposed to display between the 'contains' and 'characters.'
However, if I go to the function and cout the length, the cout in the main body displays just fine.
Here's the main portion :
cout << "'" << input << "' contains "; //Output of character count.
charCount(input);
cout << " characters, including any spaces.
"; //Output of character count.
and here's the function.
int charCount(char *string) {
int length = 0; //Variable to hold the number of characters.
//Gets the number of characters contained in *string and puts that number into length.
[Code] .....
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Nov 21, 2014
As the title says, i'm using a function which returns a pointer to a struct:
the struct is the following:
Code:
typedef struct POINT
{
uint16_t x;
uint16_t y;
}
Coordinate; the function i'm using:
Code:
Coordinate * Read_XTP2046(void)
{static Coordinate screen;
//calculations to determine the coordinates
screen.x=(temp[1]+temp[2])/2;
screen.y=(temp[0]+temp[2])/2;
// and so on...
return &screen;}
The question is: how do i catch this pointer and make it into a Coordinate struct in which i can read the x and y.
In my main program i would do the following:
Code:
Coordinate cor;
cor = Read_XTP2046();
This does not work, as the function returns a pointer, but how to transform this pointer into a Coordinate struct.
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Mar 7, 2014
Here's a small portion of my program:
Code:
int choice(void) {
char buffer[BUFSIZ];
char answer;
printf("
[Code] .....
I am wondering which is correct to use
Code: return choice();
or
Code: choice();
return num;
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Mar 31, 2013
I need to create a function which will print a list from 100Hz to 1000Hz then 1000Hz to 9000Hz. I have created a function in order to calculate and set up the frequency values from 100Hz to 9000Hz using two for loops as shown below. However I am unsure how to return this to the array at the main.
int main(void) {
double Frequency[18];
system ("PAUSE");
return(0); } double Frequency (void)
{
int count;
[Code]....
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Apr 15, 2013
I am using two threads and i want to take value of a function from one thread and use it in other. I am not good at the concepts of threads. Here is the following code:
Code:
void ThreadA(void const *argument){
uint32_t status = I2S002_FAIL;
status = I2S002_Config(&I2S002_Handle0, &I2SConfig_U0C1_A);
if (status != DAVEApp_SUCCESS) {
[Code] ....
So, i want to use the return value of temp_buffer from ThreadB into Thread C and want to put this value to TXBuf in ThreadA...
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