let me start by saying I know this is a funky way to program, but my teacher is requiring us to go about it this way.
also:
I CANT use std::string, classes, constructors for this project.
I am required to use this archaic method of c-style strings with dynamic memory allocation occuring outside the struct.. i know its not the best way to go about this, but theres nothign i can go. :(
Im stuck with the structs, I cant figure out whats wrong..
I have a struct
#include <iostream>
#include <fstream>
#include <ctime>
#include <stdlib.h>
#include <string>
using namespace std;
//global constant(s)
const int maxCards = 52;
//Structs
struct card
{
char *suit;
char *rank;
int cvalue;
char location;
};
//Function List
void readPlayers(player *peoplePointer);
void shuffleCards(card *unshuffled, card* shuffled);
//program
int main()
{
//create pointer and set initial value
card * deckPointer = new card[52];
card *deckHome = &deckPointer[0];
for(int i=0;i<maxCards;i++)
{
(*deckPointer).suit=new char[8];
(*deckPointer).rank = new char[7];
deckPointer++;
}
deckPointer = deckHome;
cardInit(deckPointer);
readDeck(deckPointer);
//sets default values for the card arrays
for(int i=0;i<52;i++)
{
strcopy((*deckPointer).suit,"suit");
strcopy((*deckPointer).rank,"rank");
(*deckPointer).cvalue = 0;
deckPointer++;
}
deckPointer = deckHome;
return 0;
}
//Functions
void cardInit(card *deckPointer)
{
card * deckHome = NULL;
deckHome = &deckPointer[0];
//set up card file to be read in
ifstream fin;
char *finName = new char[13];
//get file name from user
cout << "Enter file name...(cardFile.txt)" << endl;;
cin >> *finName;
//open the file
fin.open(finName);
//check if cardFile.txt opens correctly
if(!fin.good())
{
cout << "Error with card file" << endl;
}
else
{
deckPointer = deckHome;
while(fin.good())
{
for(int i=0;i<50;i++)
{
fin >> (*deckPointer).suit;
fin >> (*deckPointer).rank;
fin >> (*deckPointer).cvalue;
deckPointer++;
}
}
}
delete [] finName;
}
//Its a pretty simple program..and my dynamic memory works for
//the file name, but I cant figure out why it doesnt work for structs?
For your code to work, you will need a typename card.
to this end you will need to setup the following:
struct cardstruct {
char *suit;
char *rank;
int cvalue;
};
typedef struct cardstruct card;
otherwise, when you declare the pointers, you would need to use the "struct" keword first. E.G.:
struct card *deckPtr = new struct card[52];
Related
I am trying to dynamically allocate an array and whenever it gets to the part where it dynamically allocates the program exits. I would rather not use vectors as I am trying to learn how to do this using dynamic arrays.
This is the simplified code:
#include <iostream>
#include <string>
using namespace std;
class Student
{
private:
double calcAverage(double* testArray);
char calcGrade(double average);
public:
int nTests, sameTests, idNum;
string name;
double average, *testArray;
char grade;
};
int i;
Student fillStudentArray(int nStudents);
int main()
{
*studentArray = fillStudentArray(nStudents);
return 0;
}
Student fillStudentArray(int nStudents)
{
Student *newStudentArray = new Student[nStudents];
cout << "If you can see this I worked. ";
delete[] studentArray;
return *newStudentArray;
}
I have tried the solution posted here Creation of Dynamic Array of Dynamic Objects in C++ but it also exits in a similar way. The main for the code looks like this.
int main()
{
int nStudents = 3; //this number is just for testing, in actual code it has user input
Student** studentArray = new Student*[nStudents];
cout << "1 ";
for(i = 0; i < nStudents; i++)
{
cout << "2 ";
studentArray[i] = new Student[25];
cout << "3 ";
}
return 0;
}
close (heres a cigar anyway)
Student* fillStudentArray(int nStudents); <<== function must return pointer to students
int main()
{
int nStudents = 3; <<<=== declared nstudents
Student *studentArray = fillStudentArray(nStudents); <<< declare studentArray
return 0;
}
Student *fillStudentArray(int nStudents) <<<== return pointer
{
Student* newStudentArray = new Student[nStudents];
cout << "If you can see this I worked. ";
// delete[] studentArray; <<<== what were you trying to delete?
return newStudentArray; <<<=== return pointer
}
the second code you showed is not relevant, its creating a 2d array
I have been working on a project for my computer science class and have encountered an issue with the code working. I am shown no error except when I try to compile and I get an error that reads:
Exception thrown: write access violation.
_Left was 0xCCCCCCCC.
The purpose of my project is to take a list of names from an external file, read them into an array, sort said array and then output the sorted list all while using a class for the code.
Here is a copy of my code and I would like to extend my gratitude to whoever can help me through my issue:
**Header File**
#include <iostream>
using namespace std;
class person
{
public:
person();
bool get(ifstream&);
void put(ofstream&);
private:
int capacity = 0;
string first_name[CAPACITY];
string last_name[CAPACITY];
int age[CAPACITY];
};```
**Header function definitions cpp file**
#include<iostream>
#include<string>
#include<fstream>
#include<cstdlib>
const int CAPACITY=20;
using namespace std;
#include "Person.h"
//Names constructor
//Postcondition both first name and last name initialized to zero
person::person()
{
first_name[CAPACITY] = "";
last_name[CAPACITY] = "";
age[CAPACITY]=0;
}
bool person::get(ifstream& in)
{
in >> first_name[CAPACITY] >> last_name[CAPACITY] >> age[CAPACITY];
return(in.good());
}
void person::put(ofstream &out)
{
out << first_name[CAPACITY] << last_name[CAPACITY] << age[CAPACITY];
}
**cpp file which holds main**
#include<iostream>
#include<cstdlib>
#include<fstream>
#include<string>
const int CAPACITY = 20;
using namespace std;
#include "Person.h"
void pop(string *xp, string *yp);
void sort(string name[CAPACITY], int count);
int main()
{
class person names[CAPACITY];
ifstream infile;
ofstream outfile;
string filename;
string name[CAPACITY];
int n = 0;
cout << "Enter the file name you wish to open" << endl;
cin >> filename;
infile.open(filename + ".txt");
outfile.open("Person_New.txt");
if (infile.fail())
{
cout << "The file requested did not open" << endl;
exit(1);
}
while (!infile.eof())
{
names[n].get(infile);
n++;
}
sort(name, CAPACITY);
for (int i = 0; i < CAPACITY; i++)
{
names[i].put(outfile);
}
cout << "The file has been created" << endl;
infile.close();
}
void pop(string *xp, string *yp)
{
string temp = *xp;
*xp = *yp;
*yp = temp;
}
void sort(string name[CAPACITY], int count)
{
int i, j;
for (i = 0; i < count - 1; i++)
{
for (j = 0; j < count - i - 1; j++)
{
if (name[j] > name[j + 1])
{
pop(&name[j], &name[j + 1]);
}
}
}
}
Once again Thank you for any support
It sounds to me like the compiler is getting upset that you are trying to write (i.e. assign a value) at an address that you do not have permission to access. I believe your constructor for the class person might be at fault because of how this class stores its variables, as well as the class header:
Constructor for the class person:
`person::person(){
first_name[CAPACITY] = "";
last_name[CAPACITY] = "";
age[CAPACITY] = 0;
}`
Class header for the class person:
`class person{
public:
//stuff
private:
int capacity = 0;
std::string first_name[CAPACITY];
std::string last_name[CAPACITY];
int age[CAPACITY];
//more stuff
}`
C++ is very specific about its naming conventions, so it makes a distinction between capacity and CAPACITY. Because of this, the variable CAPACITY is not defined within the Person.h file.
Also, because CAPACITY is set to a fixed value in your Person.cpp file, whenever you use first_name[CAPACITY], last_name[CAPACITY], or age[CAPACITY] to assign new values, you are only updating the values at the index equal to CAPACITY unless you update the value of CAPACITY itself. In the code you provided, CAPACITY is equal to 20, so your program attempts to update exclusively index 20 with each method call. This will likely cause issues since the person class only attempts to make its arrays on the runtime stack, with a size of 0 each.
Separately, it seems like you want an array of people, but it appears that you are attempting to use a single person object to store the names and ages of multiple people by making these all arrays. Instead, I would recommend making first_name, last_name, and age not arrays, but rather single variables. Then, you can manipulate an array of type person using your CAPACITY variable. You got pretty close, but you can instead declare it as person myPersonArray[CAPACITY] (no need to mention "class" in front of it -- just be sure that you have #include "Person.h" in your main.cpp file). When you want to update a specific person, you can perform an operation like myPersonArray[updateThisIndexNum].update(newFirstName, newLastName, newAge) or some logical equivalent.
As a final note, I almost always highly recommend against using !infile.eof() to control your while loop when reading any file because eof() only indicates whether you have tried to read past the end of an input file. I would highly recommend checking out this post on Stack Overflow where people far more knowledgeable than I explain exactly why this is usually dangerous and how to avoid it.
I am reading data from a file in a function and saving the data to a temporary array. Then I am passing the array to a pointer inside a structure. But when I check the output in the main function, the data that I am reading is compromised and there is memory leakage for some values.
I want to know how I can read the data in the main function without causing memory leakage.
#include <iostream>
#include <fstream>
#include <string>
#include <cstdlib>
#include <cstring>
using namespace std;
struct myWeather
{
wchar_t *cityName;
float *temperature, *pressure, *direction, *wind;
myWeather *next, *prev;
};
myWeather *readData();
int main()
{
myWeather *location, *currLoc;
location = readData();
currLoc = location;
for(int c=0; c<49; c++)
{
cout<< "temp value"<< c+1<<": "<< (*currLoc->temperature+c)<<endl;
}
for(int f=0; f<1441; f++)
{
cout<< "pressure value"<< f+1<<": "<< *(currLoc->pressure+f)<<endl;
}
for(int g=0; g<720; g++)
{
cout<< "Dir value"<< g+1<<": "<< *(currLoc->direction+g)<<endl;
}
for(int h=0; h<720; h++)
{
cout<< "Wind value"<< h+1<<": "<< *(currLoc->wind+h)<<endl;
}
return 0;
}
myWeather *readData()
{
myWeather *headPTR;
char cityText[80];
wchar_t cityNym[80];
string myCity;
float tmpData[49], prsData[1441], winData[720], dirData[720];
int len;
ifstream weatherFile ("Data.txt", ios::in);
headPTR = new myWeather;
getline(weatherFile, myCity);
len= myCity.length();
myCity.copy(cityText, len, 0);
cityText[len]='\0';
mbstowcs(cityNym, cityText, strlen(cityText)+1);
headPTR->cityName = new wchar_t;
headPTR->cityName= cityNym;
weatherFile>> cityText;
weatherFile>>len;
for(int a=0; a<49; a++)
{
weatherFile>>tmpData[a];
}
headPTR->temperature = new float;
headPTR->temperature = tmpData;
weatherFile>> cityText;
weatherFile>>len;
for(int b=0; b<1441;b++)
{
weatherFile>>prsData[b];
}
headPTR->pressure= new float;
headPTR->pressure= prsData;
weatherFile>> cityText;
weatherFile>>len;
for(int d=0; d<720; d++)
{
weatherFile>>dirData[d];
}
headPTR->wind= new float;
headPTR->wind= dirData;
weatherFile>> cityText;
weatherFile>>len;
for(int e=0; e<720; e++)
{
weatherFile>>winData[e];
}
headPTR->direction = new float;
headPTR->direction = winData;
weatherFile.close();
return headPTR;
}
First of all in your case instead using an array you should use old std::vector<float> and wstring (for cityName). This is exactly what you need.
In case of next and previous you can use std::unique_ptr for next and raw pointer for previous.
Basically it may look like this:
struct myWeather
{
std::wstring cityName;
std::vector<float> temperature, pressure, direction, wind;
std::unique_ptr<myWeather> next;
myWeather prev;
};
But on other hand it looks like you are implementing double linking list which is already provided, so IMO this aproach is better:
struct myWeather
{
std::wstring cityName;
std::vector<float> temperature, pressure, direction, wind;
};
using WeatherRecords = std::list<myWeather>;
So in fact you do not need any fancy pointers or use new delete operators.
I am working on a C++ project for school in which the program will read in a list of numbers from a text file, store them in a dynamic array, then print them out to another text file. To be honest I'm a little lost with the pointers in this, and I am getting the error "A value of type "void" cannot be used to initialize an entity of type "int"" in my main source file.
Main.cpp (this is where I'm getting the error):
#include "dynamic.h"
int main
{
readDynamicData("input.txt","output.txt");
}
dynamic.cpp (the skeleton for the program):
#include "dynamic.h"
void readDynamicData(string input, string output)
{
DynamicArray da; //struct in the header file
da.count = 0;
da.size = 5; //initial array size of 5
int *temp = da.theArray;
da.theArray = new int[da.size];
ifstream in(input);
ofstream out(output);
in >> da.number; //prime read
while (!in.fail())
{
if (da.count < da.size)
{
da.theArray[da.count] = da.number;
da.count++;
in >> da.number; //reprime
}
else grow; //if there are more numbers than the array size, grow the array
}
out << "Size: " << da.size << endl;
out << "Count: " << da.count << endl;
out << "Data:" << endl;
for (int i = 0; i < da.size; i++)
out << da.theArray[i];
in.close();
out.close();
delete[] temp;
}
void grow(DynamicArray &da) //this portion was given to us
{
int *temp = da.theArray;
da.theArray = new int[da.size * 2];
for (int i = 0; i<da.size; i++)
da.theArray[i] = temp[i];
delete[] temp;
da.size = da.size * 2;
}
and dynamic.h, the header file:
#include <iostream>
#include <string>
#include <fstream>
#ifndef _DynamicArray_
#define _DynamicArray_
using namespace std;
void readDynamicData(string input, string output);
struct DynamicArray
{
int *theArray;
int count;
int size;
int number;
};
void grow(DynamicArray &da);
#endif
you have to add parenthesis to main or any function:
int main(){/*your code here ...*/};
2- you are using an unitialized objct:
DynamicArray da; //struct in the header file
da.count = 0;
da.size = 5; //initial array size of 5
so int* theArray is a member data and is uninitialized so welcome to a segfault
all the members of da are not initialized so you have to do before using it.
3- also you add parenthesis to grow function:
else grow(/*some parameter here*/); // grow is a function
4- using namespace std; in a header file is a very bad practice.
tip use it inside source
5- why making inclusion of iostream and string.. before the inclusion guard??
correct it to:
#ifndef _DynamicArray_
#define _DynamicArray_
#include <iostream>
#include <string>
#include <fstream>
/*your code here*/
#endif
main is a function so it needs brackets:
int main(){
// your code
return 0; // because it should return intiger
}
And. Your grow is also a function, so if you want to call it you write grow() and it needs DynamicArray as a parameter.
It is impossible to write working programs on C/C++ any programming language not knowing a basic syntax.
I want to add a theater object into a boxoffice object in a C++ code. When I try to add it in main code, first one is added successfully. But a segmentation fault occurs for second and obvioulsy other theater objects. Here is the add function;
#include <iostream>
#include <string>
#include "BoxOffice.h"
using namespace std;
BoxOffice::BoxOffice()
{
sizeReserv = 0;
sizeTheater = 0;
theaters = new Theater[sizeTheater];
reserv = new Reservation[sizeReserv];
}
BoxOffice::~BoxOffice(){}
void BoxOffice::addTheater(int theaterId, string movieName, int numRows, int numSeatsPerRow){
bool theaterExist = false;
for(int i=0; i<sizeTheater; i++)
{
if(theaters[i].id == theaterId)
{
theaterExist=true;
}
}
if(theaterExist)
cout<<"Theater "<<theaterId<<"("<<movieName<<") already exists"<< endl;
else
{
++sizeTheater;
Theater *tempTheater = new Theater[sizeTheater];
if((sizeTheater > 1)){
tempTheater = theaters;
}
tempTheater[sizeTheater-1] = Theater(theaterId,movieName,numRows,numSeatsPerRow);
delete[] theaters;
theaters = tempTheater;
cout<<"Theater "<<theaterId<<"("<<movieName<<") has been added"<< endl;
cout<<endl;
delete[] tempTheater;
}
}
And I get segmentation fault on this line;
tempTheater[sizeTheater-1] = Theater(theaterId,movieName,numRows,numSeatsPerRow);
This is Theater cpp;
#include "Theater.h"
using namespace std;
Theater::Theater(){
id=0;
movieName="";
numRows=0;
numSeatsPerRow=0;
}
Theater::Theater(int TheaterId, string TheaterMovieName, int TheaterNumOfRows, int TheaterNumSeatsPerRow)
{
id = TheaterId;
movieName = TheaterMovieName;
numRows = TheaterNumOfRows;
numSeatsPerRow = TheaterNumSeatsPerRow;
theaterArray = new int*[TheaterNumOfRows];
for(int i=0;i<TheaterNumOfRows;i++)
theaterArray[i]= new int[TheaterNumSeatsPerRow];
for(int i=0; i<TheaterNumOfRows;i++){
for(int j=0;j<TheaterNumSeatsPerRow;j++){
theaterArray[i][j]=0;
}
}
}
This is header file of Theater;
#include <iostream>
#include <string>
using namespace std;
class Theater{
public:
int id;
string movieName;
int numRows;
int numSeatsPerRow;
int **theaterArray;
Theater();
Theater(int TheaterId, string TheaterMovieName, int TheaterNumOfRows, int TheaterNumSeatsPerRow);
};
And this is how i call add functions;
BoxOffice R;
R.addTheater(10425, "Ted", 4, 3);
R.addTheater(8234, "Cloud Atlas", 8, 3);
R.addTheater(9176, "Hope Springs",6,2);
The problematic lines are these:
if((sizeTheater > 1)){
tempTheater = theaters;
}
First you allocate memory and assign it to tempTheater, but here you overwrite that pointer so it will point to the old memory. It does not copy the memory. Since the code is for a homework assignment, I'll leave it up to you how to copy the data, but I do hope you follow the rule of three for the Theater class (as for the BoxOffice class) which will make it very simple.
Also, there's no need to allocate a zero-size "array", just make the pointers be nullptr (or 0).