class Album{
private:
char albumName[100];
Song* List;
int numSongs;
public:
Album(char*);
~Album();
[Code] ....
And everytime I create the class it can have only one song because I set numSongs to zero.
Please consider the following code :
#include <iostream>
using namespace std;
class superclass;
class subclass1;
class subclass2;
[Code] ....
As you can see I want to create a dynamically allocated storage of references to a parent class each of which can then point to a child class, how ever I do not know how to extract the child class out again from that array so i may access its variable b.
I am trying to make a double array, but I keep getting an error Segmentation fault (core dumped) when I make more than 105 elements in the array. I need to make 114 elements.
I am building my array with myarray[999] and increasing the number doesn't seem to do anything.
How can I store more elements in my array?
I am new to programming all together but i have been writing a program in c++ and im coming up against an issue with my array.
#include<iostream>
#include<iomanip>
#include<string>
using namespace
int main () {
int a ;
int b ;
char answer ('Y') ;
[Code] ....
I am trying to get the program to increase say year one by 1 when the condition is met i have tried
if ( a >= 70 && a <= 100 && b == 1)
{grade [0][0] = 0 + 1;}
and
for (grade[0][0] = 0 ; a >= 70 && a <= 100 && b == 1 ; grade [0][0]++)
{grade [0][0]= 0 + 1 ;}
Now all that i want is that the array will take the information from int a and int b and then add 1 to the appropriate part of the array . I have tried putting it in deferent places but its not working for ether. the program will run but it will not add to the array.
Working on a console application and I am trying to figure out a way that allows users to enter an object property along with a value. For example
class Box{
public:
int height;
int width;
int length;
[Code] .....
For example if a user inputs "height" for Name and "13" as value I would like to find a way to change ab's height to 13. I want to make this work so that one can add another class and get the same functionality.
I tried looking online and I think maps are a way to do this and I tried doing that but I don't know how to proceed after/what code to write that would allow me to change it.
Note: I can't use if else statements or hardcoding to match the input to member as I want to make this extensible.
regarding dynamic vector.
Shape2DLink.cpp
void Shape2DLink::InputSensor()
{
string shape,type;
[Code]....
So i'm actually using polyphormism for calculating the area of the cross and other shapes. so how do I actually make use of dynamically create an object this way?
do I create them in my Shape2DLink or in my individual child classes?
I'm trying extremely hard to understand pointers and I have the basic concept down.. I feel as though my knowledge of dynamically allocated pointers and pointers in general is not enough to understand the logic behind what I'm trying to do. The problem is that the donations array must be able to accept any number of donations. I've made it do just that, but there is also an array of pointers which must each point to the same element in the donations array. The program works if I assign int *arrPtr[100] for example, but it does not work if I try to dynamically allocate it to accept the same number of elements for donations entered by the user. Here it's the snippet
#include <iostream>
using namespace std;
//Function Prototypes
[Code]....
Consider the following:
Code:
int *p;
p = new int[5];
for(int i=0;i<5;i++)
*(p+i)=i;
Now suppose we want to add a 6th element (without using vector)
One way is to copy it across to a larger array:
Code:
int *p;
p = new int[5];
for(int i=0;i<5;i++)
*(p+i)=i;
// realloc
int* temp = new int[6];
std::copy(p, p + 5, temp);
delete [] p;
p = temp;
This looks like a very expensive operation and im looking for other ways.
Three questions regarding the above: Not using vector, is this the best way to do this?What about using realloc? How would I use realloc in this situation?Any other ways apart from realloc or vector?
I would like to realloc a 2D array. I have a counter, itime, it increases each step. Each step, I would like to reallocate my array, keeping the old values, and add new values to the array. When itime=1, I use only malloc, because it is allocated for the first time. When itime increases (e.q. itime=2), realloc comes into process. In the realloc process the GUI crashes.
int itime;
char ** solpointer;
itime = 1;
do {
if( itime == 1 ) {
solpointer = (char**)malloc(sizeof(char*) * itime);
solpointer[itime-1] = (char*)malloc(sizeof(char) * 32);
[code]....
I am working on expanding an array and my approach was to do this by copying the array into a bigger array. For this problem I cannot use vectors so what I did was the following:
int *a;
a = new int[5];
for(int i=0;i<5;i++)
*(a+i)=i;
// reallocating array
int* temp = new int[6];
std::copy(a, a + 5, temp);
delete [] a;
a = temp;
Is this approach correct, also how could I implement this on a program to expand an array to double its size or could I not use this to expand an array to double its size?
Working on this one from the Jumping into c++ book. The book asks that I create a multidimensional array at run time based on user input and fill it with a multiplication table
My code compiles fine but throws an uninitiated error for p when I try and run it.
Code:
void multiDimentionalMultiplication(int x, int y, int z){
int ***p;
**p = new int[x];
std::cout << "Allocating array.
[code]....
I want to access the elements of my array dynamically. So far I've only figured out how to do this manually. if I tried it like this my code would work but there should be a better way right?
View 10 Replies View RelatedI have declared an array like:
/***********Creating an m*p array**********************/
B = new int *[m];
for(row=0;row<m;++row)
B[row] = new int[p];
How to find the number of elements in it?
The statement
cout << "number of elements in array B equals " << sizeof(B) << endl;
returns 4 each time the program runs
I am trying to figure out the syntax to dynamically allocate a single dimension of a triple dimensional array. Basically i have a 2D array of structs. but each struct is an array (basically rows of the information). The rows of this structure need to be allocated dynamically, but the height and width of the overarching structure are static.
Basically: Struct * ts_FieldInfo[100][100] = new Struct[Class.returndataitems()];
I know I can allocate it this way, on the stack:
char* str[5];
for(i = 0; i < 5; ++i) {
str[i] = new char[STR_SIZE];
}
But if I want to allocate array size through 'new', what's the syntax for that?
I thought this might work, but it gives error: "Initialization with {...} expected for aggregate object"
char* newString[] = new char[5][ARRAYSIZE];
I have changed my const global int NUMLABS to a non constant variable so that the user can decide how many labs to input. I adjusted the parameters of each function to add NUMLABS becuase the variable is no longer constant. But now main() returns 0 right after the user chooses how many stations to put in each lab. I am having difficulty understanding these dynamically allocated arrays.
/*********************************************************************
Lab4.cpp
This program uses dynamic arrays to store login information for four labs. Each of the four labs is referenced by the labs[] array which is indexed from 0-3. A pointer in the labs[] array then references a dynamic array that is of size for however many computers are in that lab.
Written by: Luca Del Signore
Last modified on: October 3rd
Known bugs: N/A
*********************************************************************/
#include <iostream>
#include <cstdlib>
using namespace std;
[Code]....
so I have this code that dynamically allocates a pointer array increasing and removing elements of the array as its operated on.then it sorts and prints out the array when the user is finished operation on the array. i get this error message when running the program though.
"Unhandled exception at 0x0F474F98 (msvcr110d.dll) in Lab10_VarArray.exe: 0xC0000005: Access violation reading location 0xCCCCCCC0."
this is my code
#include <iostream>
#include <cstdlib>
#include "Header.h"
using std::cout; using std::endl; using std::cin;
int main(void) {
char op='x';
[Code]...
I have a structure, containing a pointer as a member. I dynamically create an array of that structure type, and then need to dynamically create an array for its pointer member.
#include <iostream>
#include <string>
using namespace std;
[Code]....
There is more of my program afterwards, but it shouldn't matter. The errors I am getting at compile time are that I cannot convert an int pointer to an int (line 29) and that test is not a member of CourseGrade (lines 44/45).
My thought is I might be using the * operator incorrectly. My code before hand in line 29 was
for (i = 0; i < numberStudents; i++)
*studentPtr[i]->tests = new int[numberTests];
but the compiler suggested a '.' rather then the '->'
Write a program that dynamically allocates an array large enough to hold a user-defined number of test scores. Once all the scores are entered by the user, the array must be passed to a function that sorts them in ascending order. It must use another function that calculates the average score. The program should display the sorted list of scores and average with appropriate headings. The program must use pointer notation instead of array notation. Validation: Do not accept negative numbers for test scores; keep prompting the user for a new grade. Do not accept negative numbers for the number of scores the user wants to enter.
#include <iostream>
#include <iomanip>
using namespace std;
// Function prototypes
double getAverage(int*, int);
void sortScore(int *,int );
[Code] ....
I have no errors in my code but when i run it and i enter a positive interger it just goes into a loop to enter a positive number.
Im having trouble on getting the quantity up of the variable "item.iqty". For example the current quantity is 5 and in this function, the user inputs a number and it should add to the variable "item.iqty". So if if the user inputs 2 then the current quantity should be 7 now but in my program it hasnt changed. its still 5
void addQty(FILE *fp)
{
int num, qty, r, c, n;
bool found;
[Code]....
I'm trying to implement a linked list using my own node class. I've created functions to add to the head and tail, return the size of the linked list as well as the value stored within the current pointer.
However, my problem is that when I wrote a test program to see whether my list worked, my list did not appear to increase in size past 1 item in the list.
this is the test program I wrote:
int main() {
int counter,
data;
linkedlist *my_list = new linkedlist();
cout << my_list->size() << endl;
for (counter = 0; counter < 5; counter++) {
[Code] ....
I'm sure it's probably something simple that I've overlooked . But I'm still relatively new to the concept of dynamic memory allocation.
Code:
#include <iostream>
using namespace std;
int j;
int n;
int recursive ( int arr[j] );
int main() {
int i;
int arr[10000];
[code]....
This is how I tried making the program..
I want it with a recursive function
I want if the sequence is non decreasing return true else return false
I'm working the 4th problem in chapter 14 of the Jumping into C++ book. In the book, he gives an example program for dynamically resizing an array while the program is running. It works fine for integer types but i need to do the same with a string type array. Right now my program is crashing because the string array is not resizing itself. Here's the part of the code im trying to figure out. The part for the int array has been ignored using // since it works fine and I'm trying to figure out whats wrong with the string array.
Code:
#include <iostream>
#include <string>
//Write a program that lets users keep track of the last time they talked to each of their friends.
//Users should be able to add new friends (as many as they want!) and store the number of days ago
[Code]......
This is a homework assignment where I have to read a file into a dynamically allocated 2d array. The file format is
10
Jim 3.6
Jake 4.0
Will 3.0
Sara 3.4
Mike 2.5
Ellen 2.9
Melissa 3.9
Eric 3.8
John 3.5
Beth 3.9
where 10 is the number of students followed by the students and the gpa's. There is more to the program but I have not implemented it yet because I am getting a segmentation fault. The output I am getting when I print the array is
Jim 3.6
Jake 4.0
Will 3.0
Sara 3.4
Segmentation fault
I can see where the problem lies. If I raise value for row when I am allocating the rows of the array, all of the names print. I just do not see why I need to. From my understanding the row * sizeof(char*) should give me enough room for 10 entrie.
Code:
#include <stdio.h>
#include <stdlib.h>
void sort();
int main()
[Code] .....
Suppose I wished to initialize a dynamically allocated array of integers to zero. Would I do better to use calloc() or malloc + iterate over all entries setting each to zero? Which one is regarded as a better approach?
View 12 Replies View RelatedCode:
void readFile(struct course *d, char* filename){
FILE* fp;
char buffer[100];
int i = 0, array_size = 100;
struct course *temp;
[code]....
I will be using this to read data from a file. I start with an array of 100 structures being passed to the readfile function. Once it reads 100 lines (i == array_size), I want to double the array size until I have finished reading the file.
Two questions.
1)My initial thought was that I needed to keep track of the lines read with my variable, i. However, is there a better way?
2)My program is crashing right now at the call to double_array_size function. What is wrong with my code? Never dealt with dynamically allocated array of structures and functions.
I read online that I should change my code in the following manner.
Code:
void readFile(struct course *d, char* filename) {
FILE* fp;
char buffer[100];
int i = 0, array_size = 100;
struct course *temp;
[code]....
I can paste the "error messages" if you like, but it is a page full of stuff I have never seen. glibc detected, Backtrace, Memory Map, and a bunch of numbers and hexadecimal stuff like addresses.