C++ :: Class Instances To Text File
Mar 29, 2015
Code:
#include<iostream>
#include<conio.h>
#include<string.h>
#include<ostream>
#include<fstream>
#include<iomanip>
using namespace std;
class MathProblem {
[Code] ...
So my program is quite simple, have the user answer the answer to a question, and then compare with the correct answer. I needed to implement an inheritance of MathProblem in my second class aswell.
The program runs as I intend but I wish to have the data forwarded to a text file. After that I must read back to the command prompt the text file contents. It's fairly easy for simple statements but I don't understand how to forward all my data from my classes.
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Nov 10, 2014
I am trying to do some exercises but am struggling at the moment. The first task was to create a class (Planet), then allow the user to edit their entry or view it.
The second one is to create class instances from a text file. The file contains a new planet on each line in the form: 'id x y z' where x/y/z are its coordinates. As the file can have more then one lines, it has to dynamically create an undefined amount of class instances.
To do this I used 'new' and it works ok - it prints each one out to the screen as you go so you can see it working. However... I'm trying to get into good habits here and am encapsulating the class which is where I am getting stuck. I can read from the class but cannot put the values from the file into the class.. ..using the member functions I have created anyway.
My code so far is:
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
class Planet {
private:
int id=0;
float x_coord=0.0, y_coord=0.0, z_coord=0.0;
public:
int GetID(){return id;}
[code]....
If I change the SetID etc to just p->id, p->x_coord etc it works fine. But I'd rather find a way to do it that keeps the encapsulation. Using p->z_coord etc requires that you change the class variables from private to public.
The question I have been given is this:
Define and implement a function, generate planet, that takes a stream argument that has already been connected to a file (i.e. the argument is istream& fin). The function must create a new instance of planet using new and read its details from the next line in the file.Each line of the file is in the format id x y z.The function must return the newly created planet.
Also, how would you go about 'viewing' one specific class instance once they've been created? So say the file had 5 lines, line three was '4 6 2 6'. How would I go about viewing that planet afterwards? I don't think thats required but... I'm just wondering Although I'm also wondering, are we actually creating a new class instance for each line here? Or just destroying the previous one?
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Aug 22, 2013
I can't get my code to compile, i need to read in lines from a file and store them in variables. Then i have to construct instances of my class for how many lines there are in the file and take those variables into them.
I'm getting this error :
"a2.cpp:40: error: cannot convert `Employee' to `Employee*' in assignment"
#include<iostream>
#include<string>
#include<fstream>
void displayInfo();
using namespace std;
class Employee{
[Code] .....
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Feb 1, 2015
I am struggling to understand what the correct way to initialize instances of a class for object orient programming is.
If I am not mistaken, there are 2 methods to initialize an instance "instance_name" of CLASS1 by calling the constructor:
(1) CLASS1 instance_name(argument);
(2) CLASS1 instance_name=CLASS1(argument);
As it turns out, I cannot use method (1) when I try to initialize a private instance inside another class. But I can use it in the main() code. I hope the code below will explain what I mean. Why only method (2) will work inside another class? Or is there another fundamental mistake I am making?
(BTW: I used CodeBlocks 13.12 with GNU GCC compiler for this example)
#include <iostream>
using namespace std;
class CLASS1{
[Code].....
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Jun 17, 2012
i have this rather large class, which (in a way) somehow resembles a custom dialog control). This control is supposed to display data, which it does just fine. To do so, it maintains a
byte settings[10];
array, which holds information on how to display the data.
There are multiple ways to represent this custom set of data.In order to remain flexible in representing it, i thought of implementing some sort of DisplayProvider, which can be registered to the base class and provides that settings byte array.
Preferably, i would now have a set of static const instances of this provider.Using a struct would work nicely here:
PHP Code:
struct DisplayProvider
{
int settings[10];
}
static const DisplayProvider prov1 = {1,2,3,4,5,6,7,8,9,0};
The problem: The DisplayProvider would have to do some pre-processing, before handing over control to the base class, which then does the main work.I would end up with something like this:
PHP Code:
class DispalyProvider
{
baseclass* owner;
int settings[10];
void PreProcessing(...);//ends up calling the owner.Processing(...) function
};
The main thing here is, that i dont really see a way to create a stock of default "static const DisplayProvder = {...}"s, as i could when using a struct.
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Feb 10, 2015
Using SFML, I had a Board class which held multiple vectors of all of my object types in the game, and then it also held a vector of pointers to the memory addresses of these object instances, like this
class Board{
//...
std::vector<AbstractObject*> GetAllLevelObjects(){ return allLevelObjects; }
//so these are used to hold my object instances for each level
[Code]....
When looping through this vector and drawing the sprites of the objects, I get the runtime error 0xC0000005: Access violation reading location 0x00277000. I solved this error by storing the vector of pointers in the class that holds my Board instance, but I'm wondering why only this solution worked? Why couldn't I just have my vector of pointers in the same class that the instances of those objects were in?
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Mar 24, 2012
I'm trying to search a specified file for all instances of substring "abbaa."
The professor is making us use a 6x3 array in order to understand finite state machines.
Well the code I wrote runs perfectly, but the case for '/n' doesn't catch. It just flows through without it.
Significant portion of code:
Code:
if(fin) {
fin >> inChar;
while(fin) {
switch(inChar) {
case 'a':
currentState = state[currentState][a];
[Code] .....
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May 22, 2014
I'm having trouble in getting my program to read from a file and put all the proper data into its proper class variables. I have a class (called Champion) that has string variable for a name and a vector of strings for items. I also have a vector of Champion that holds multiple champions. Here's my code:
Champion.hpp
#ifndef CHAMPION_HPP_INCLUDED
#define CHAMPION_HPP_INCLUDED
#include <iostream>
[Code].....
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Apr 20, 2014
I need to make a program which reads multiple lines from a text file and stores that information in a vector of structs(the vector class template also needs to be custom made).
One of my requirements is to have a class dedicated for I/O for the text file. At the moment I can't seem to get a way to input the data from a file into a vector from an InputOutput class. This is my code:
InputOutput.h
#include <ostream>
#include <fstream>
#include "Share.h"
#include <string>
#include "Vector.h"
class InputOutput {
[Code] ....
This is the menu selection function in the menu.cpp where i figured i would call the Input file and store it from case 1. I think I'm doing it wrong though. Is there a better way of doing this because at the moment i am getting some errors such as error LNK2019.
void Menu::UserMenuSelection() {
Vector<Share> shares;
std::ifstream infile;
switch (menuOption) {
[Code] ....
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Jan 15, 2014
I need to a simple example for writing class' objects to a text file using fstream , I tried to search the forums and I found binary examples but not for to a text file.
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Jan 21, 2014
So I'm rewriting an old project of mine, and I'm trying to determine if there's truly any better way to map the data taken from a text file "dictionary" into the correct class fields for further processing. For example:
FNAME=MY_FIRST_NAME
ADDR=123 SOMEWHERE LN, NOWHERESVILLE, TX 01234
LNAME=MY_LAST_NAME
TOTCALLS=47
In each of these, I'd need the "value" (MY_FIRST_NAME, MY_LAST_NAME, etc) from the "keys" (FNAME, LNAME, etc) to be mapped to the proper class fields. Say, for example, I had this:
Class DataProcessing {
public string Address;
public string FirstName;
public string LastName;
public int TotalCalls;
...
}
I would need DataProcessing.Address to be set to the value in the ADDR key/value pair. The same would be true for each other field. The problem is that based on the text file's source (which isn't under my control, and won't be changed anytime soon), the key/value pairs are not always in the same place...so a second file could have the data as such:
TOTCALLS=47
ADDR=123 SOMEWHERE LN, NOWHERESVILLE, TX 01234
LNAME=DARKPOETCC'S LAST NAME
FNAME=DARKPOETCC'S FIRST NAME
Any smarter way to do this than looping through each line that was read in from the file, and determining where it belongs, such as (pseudo code follows):
IF FieldName == "TOTCALLS" THEN
//Assign to TotalCalls field
ELSEIF FieldName == "ADDR" THEN
//Assign to Address field
ELSEIF FieldName == (You get the picture...)
//Do thing N_Field
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Nov 29, 2014
Code software that, from an original text file, generate another file with the text content in upper case.For exemple:
entrence:
luke
tom
alex
outings:
LUKE
TOM
ALEX
My code so far:
Code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
}
[code]....
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Oct 29, 2014
Code:
cout<<"Enter Filename for input e.g(inp1.txt .... inp10.txt):"<<flush;
cin>>filename;
ifstream inpfile;
inpfile.open(filename,ios::in);
if(inpfile.is_open())
[Code] .....
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May 28, 2013
So I am wondering how I would go about calling a function for all instances of an object. I tried googling it, but all I saw was solutions like making an array of pointers to the objects. What if I don't know how many objects there will be? Isn't there an easier way?
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Sep 3, 2013
template <typename T> struct avl_tree {
T data;
int balance;
struct avl_tree <T> *Link[2];
static int (*comp)(T, T);
};
In main, I have a function like so:
int compare(int a, int b) {
return ( a - b );
}
Now how do I assign the function pointer in my avl_tree class to the compare function?
I did this:
int (avl_tree<int>::*comp)(int, int) = compare;
But I got the compiler error:
Tree_Test.cc: In function ‘int main()’:
Tree_Test.cc:27:42: error: cannot convert ‘int (*)(int, int)’ to
‘int (avl_tree<int>::*)(int, int)’ in initialization
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Dec 18, 2014
Understanding Fork() calls. I have to write a C program in UNIX machine, and make two Fork Calls Inside it and have these two instances run every five minutes all round the clock. How to achieve this.
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Oct 4, 2012
is it possible to have a global variable pointing to a different address depending on the thread?
Imagine one would like to use threads with the loop:
for (i=0;i<n;i++){
globalPointerVariable=getAddress(i);
DoThingsUsingThe_globalPointerVariable();
}
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Jun 5, 2014
I want to make a program that opens a text file and checks the usernames listed in the text files to see if the names are registered on a site such as twitter. How easy would this be to make, what things would I need to know?
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May 31, 2013
I am trying to get text file and read only first 100 lines of the text content using c/c++. how can i do it?
is it something like string line;
getline(stream,line);
??
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Aug 30, 2013
I have a huge text file in following format:
{Bunch of text
.
.
}
[Code].....
I want to extract Text1, Text2, Text3, Text4,..., Text600 in the output file. How can i achieve this?
/* BTW, I am not getting my homework done here. I am an ex-programmer, who has now moved to marketing for some time now, and today, I encountered this problem, which I believe can be solved easily through programming. */
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Aug 31, 2014
i want to create 100 gmail accounts instantaneously....what i want from you guys is i have written a program that create a text file i want that once i give the program the imput of 1 it should delete the first 3 lines from the file i.e. the first account details coz that is already been created and shift the rest of it 3 lines upwards after that i'll write a javascript that will automatically fill and create the accounts with those names in web browser.....my lil program is here:
#include <stdio.h>
#include <conio.h>
main()
[Code]....
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Mar 31, 2013
Here is what I have going on.
Code:
struct client {
char firstName[stnd];
char lastName[stnd];
long ID;
char email[stnd];
float funds;
float wager;
}
typedef client...I would like to have these fields filled with this function below and stored in an array... Basically Multiple users and this is my function for it, if I can get it to work proper -.- .... I don't get syntax errors but I do get warnings
Code:
void getct(client *cl, int *pclientCounter) {
char input[buff];
char *pinput = NULL;
int typef = 0;
int lengthf = 0;
}
[code]....
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Jun 23, 2014
I am getting an error with my while loop(feels dumb) when running this code that I am allowed to modify. It is to remove all instances of an element within the list.
The loop is whithin this function:
void arrayListType<elemType>::removeAll(int location)
I have attached both the header file and main function file in .txt format.
void arrayListType<elemType>::removeAll(int location)*
Attached File(s) :
header.txt (12.23K)
main function.txt (2.95K)
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Aug 2, 2014
I have a text file called (Test.txt) with the following text:
This is line one
This is line two
This is line three
How do I go about writing a program that will print a line of text (e.g. "This in line two" on the console screen?
All I can seem to do is display the entire text file.
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Sep 18, 2013
I am trying to compile a c program for sudoku. I have declare const instances as global variables, but when i try to compile the code it says that my declarations are not constant, here is some of the code.
#include <stdio.h>
#include <assert.h>
const int GRIDSIZE = 3;
const int GRID_SQUARED = GRIDSIZE * GRIDSIZE; //this line
const int ALL_VALUES = (1<<GRID_SQUARED)-1; //and this give//the error
int board [GRID_SQUARED][GRID_SQUARED];
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Mar 28, 2014
look at this code:
#include <iostream>
using namespace std;
class teste
[Code]....
Each time i call "x = new teste();" the previous object is deleted? Does this code cause any sort of memory leak?
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