Getting back into programming after a few years off and a bit rusty.
My question is: Is this going to initialize the size of the vector array's position and color properly?
#include <GLFW/glfw3.h>
#include <vector>
class TerrainClass {
private:
struct VertexType {
std::vector<float> position[3];
[Code]...
I am creating a class that has a private array on the heap with a constructor that takes the size of the array and initializes it on the heap. Later I have to make a deconstructor delete the space and print out free after.In my code, I was able to heap a private array and make a deconstructor, but I don't know how to take the size of the array and initialize it on the heap. My guess is this:
int* size = new int();
Also when you initialize size on the heap, don't you also have to delete it too? If so, where, in the code, do you do that? Here is my code so far.
Class Student {
private:
int size;
int* array = new int[size];
public:
Student(); // Constructor
~Student(); // Deconstructor
[code]....
How do you make a constructor that takes the size of the array and initializes it on the heap
Student::~Student()
{
delete[] array;
cout << "Free!" << endl;
}
Is it generally better to initialize string data members as nullptr or as a zero-size array?
I can understand the former is superior from a memory-use perspective and also not requiring the extra allocation step. However, many string management functions will throw an exception - wcslen for instance - if you pass them a null pointer. Therefore I am finding any performance gained is somewhat wiped out by the extra if(pstString==nullptr) guards I have to use where it is possible a wchar_* may still be at null when the function is called.
I want to save the char[8][8] // fixed size 2 dimension array
to a vector
such as
vector<?????> temp;
is there anyway to approach this?
I am trying to use an array of a size that will be determined by the user, therefore I must use a vector, right?
In class I was told that this is how I call a vector:
vector <int> x;
Is the vector called vector? Is it called x?
Can I do this?
for(int i=0;i<=10;i++)
{
cout<<x[i];
}
Some basic ways of implementing a vector? How it works or how I can do anything with it.
I want to make a class, named generation, having a vector<chromosome> type data member.
chromosome is also class name.
chromosome has a 'route' as data member, which type is class TArrayI defined in ROOT package.
the size of route is to be fixed according to parameters of generation class object.
class chromosome{
public: chromosome(){;}
....
protected:
TArrayI route;
};
class generation{
public: generation(int PopSize=300, int numCity = 36){
.........
}
vector<chromosome> Population;
};
I want each element, chromosome of Population, to have a numCity size of route.
What I have to do is write a small program in C++ to parse the symbols that are used on 5 different lines of text in each position until position 30 is reached on each line. The goal of the parsing program is to interpret the symbols (characters), if there are any per each position, on the 5 lines of text in order to output the actual data that the group of symbols represents.
My question for is this: Is there anything special from a C++ environment that should go in to something like this outside of using standard stuff like the math associated with the search algorithm that has to happen here? The symbols are located in a file, so I know I have to include "iostream" and a few other headers. But outside of header inclusions and the code necessary to iterate and streamline the search and interpretation process, am I missing anything special that I couldn't otherwise find through simple google searches?
For example, I have an empty vector of integer. If I keep calling push_back on vector, is it going to be out of memory?
View 8 Replies View RelatedTrying to define some global colors so I can use the one instance though-out my application. Here is my color code:
<Color x:Key="GlobalTextColor">#E0E0E0</Color>
But this color doesn't display in the list when I start to type {StaticResource ...}
This is the code where I'm trying to reference the color, see Stroke="{StaticResource GlobalTextColor}". GlobalTextColor doesn't actually come up in the list so won't work.
<Style x:Key="InputButton" TargetType="Button">
<Setter Property="Background" Value="#FF141414" />
<Setter Property="HorizontalAlignment" Value="Left" />
[Code].....
My program enters the size of the vector from the user and then creates a vector of vectors (lets say SIZE1). In addition the user enters the number of vector of vectors he needs (lets say SIZE2) as follows:
class Vectors {
// member functions goes here
private
vector<vector<int>> vectors;
vector<int>::iterator it;
[Code] .....
With a few calculations and insertions to my vector (vector of vectors)... the program works fine and gives me the results...
However, with huge calculations and insertions the program stops working and gives me this message
"Unhandled exception at at 0x770DC41F in Test.exe: Microsoft C++ exception:std:bad_alloc at memory location 0x001CEADC"
Thus, it seems that the vector reached it's maximum size... I tried to use reserve() but did not work
I read that "By default, when you run a 64-bit managed application on a 64-bit Windows operating system, you can create an object of no more than 2 gigabytes (GB). However, in the .NET Framework 4.5, you can increase this limit"
What do you think would be the best option for me to do (note my program is very long and complex)(I'm currently using Microsoft Visual Studio 2012 32Win application):
1. convert my program to the .NET Framework (C++)
2. convert my program to C# in case c#
3. do any settings on my computer (my workstation has a 3.6GHZ xion processor with 32RAM
4. convert to another version of C++ that does not have any restriction on the size of the array (if available)
Please note that I never worked neither with the .NET framework nor C#
I had a question about memory allocation/how iterators work for a std::vector<foo> of a user defined class 'foo'. Say foo contains variables of variable size, so that each member of the std::vector<foo> does not require the same amount of memory space.
Does c++ allocate the same amount of memory for each element, equal to the amount of memory required for the largest element? Or does it use some sort of array of pointers pointing to the location of each element in the vector to make the iterator work? Or does it use some other method? I am wondering because I wrote a code which reads data from a binary files and stores most of it in std::vectors.
The code seems to be using significantly more memory than the sum of the size of all the binary files, and I am using vectors made up of the datatype within the binary files (float). So I was wondering if internally the code was allocating space for each vector element which is the size of the largest element as a way to handle indexing/iterators. I ran my code through a memory leak checker and it found no errors.
I'm trying to do is write a program that fits to a separate test program. The test program provides different size vectors that my function should try and binary search. If the element is found, the function should return 1, and if the element is not found, it returns -1.
Here is the code:
int binSearch(const vector<double> & data, int elem, int & comps) { {
int beg=data[0];
int end=data[data.size()-1];
int mid=(end+beg)/2;
[Code] ......
The problem is that one of the vectors my function is supposed to binary search is a vector of size 0. I tried to throw in an if statement that would return -1 if the size was == 0, but then the program never fully completed and just kept running. So, how can I account for a size 0 vector in my function?
My program takes the values from one array and searches for their index position in another array (linear search algorithm). This is an example of the issue im having(its not part of the actual code below)
a[]={1,2,3,4,5,6}
Arr[]={1,2,2,3,4,5}
If it finds 1 in arr, it returns 0, which is fine but if it finds 2 in arr it return 1 and 1 instead of 1 and 2.
for (int q=0; q=size2;q++) {
int rs=secfunc(array1;size1;array2[q])
if(rs>=0) {
cout<<rs << "";
[Code] .....
Example :
Code:
struct x {
int v[4];
};
const x test = { 0, 1, 2, 3 };
Why can I do this? How does the compiler know to write to this in the proper way? I get that v would be contiguous. Does that have something to do with it?
I am trying to initialize an array of pointers to an array of characters, I can do it in 3 lines but I really want to do it in one line at the same time keeping the #define.
3 lines initialization (can compile)
======================
#define A 1
#define B 2
char row1[] = {A|B, B, A};
char row2[] = {B, A};
char *test[]= {row1, row2};
1 line initialization (failed)
===============================
char *test[] = { {A|B, B, A}, {B, A} }; // <- how do i do this??
I do not want this because it waste ROM space
=============================================
char test[][3] = { {A|B, B, A}, {B, A} };
There are two class.How can I initialize an array of different class in a constructor?
class Ticket{
private:
int ID;
[Code]....
I have to provide a no-argument constructor (Cinema();)to initialize the ticket array and give the right ticket ID.
imagine you have a world class. Than you have a tile class. Now, in the world class is a array with a lot of tiles and I want to initialize them with my imagination(For example I want a grass floor). But how I can do this, the array can only be create with the standard constructor. But it would be stupid and not very fast, that the tiles are first initialized with the standard constructor and than overridden to build the world. Whats the best way to initialize such a array ?
View 12 Replies View RelatedI am writing a raytracer, and currently I'm working on creating a bounding volume hierarchy to accelerate the process. To do this, I am first creating a vector that holds each of the objects in the scene, and passing this vector to the constructor for my BVH.
Code:
//in header
BVH_Node* bvh;
//in main raytrace function
[Code] .....
I am testing a scene that has only 2 objects, and so it goes to the size == 2 check. The first time it hits makeLeaf(), I segfault. I've used both gdb and valgrind, and of course it's a memory mapping error. gdb's backtrace tells me that the length of the vector I've passed in is -805305610 and the capacity is -21, and that it is inside my makeLeaf() function that the error occurs.
Here's the function:
Code:
BVH_Node* BVH_Node::makeLeaf(GeomObj* v){
BVH_Node* node;
node->obj = v;
node->isObj = true;
return node;
}
The segfault happens at
Code: node->obj = v;
If I run my raytracer without a BVH, the objList works perfectly.
So for a project I'm working on, I'm using an array and generating it's values randomly but unique. Currently I'm working on a 3X3 array and the generated values are in the range from 1-9. So I wrote a function that will tell me the position of the cell whose value is 9. This is the function I wrote:
Code: void Llogaritje1(int t[3][3],int &i, int &j){
int y,l;
for(y=0;y<3;y++){
for(l=0;l<3;l++){
if(t[y][l]==9){
i=y;
j=l;
break;
}
}if(t[y][l]==9) break;
}
}
But it doesn't work on all cells. Seems like at cells t[1][0] and t[2][0] the values that i and j take are 0 0 since when I print them after excecuting the function that's what it returns. I really don't understand why.
I am currently practicing designing classes. In one exercise, I am trying to store 15 words in an array, and randomly print one (using the rand() functions and seeding it with crime. I have a header file, a respective .cpp file, and a main .cpp file. When I try to compile the code using g++ GuessWord.cpp UseGuessWord.cpp -o UseGuessWord, I get the following error in my constructor: expected primary-expression before ‘{’ token
Here is my code:
header file (GuessWord.h):
#ifndef GUESSWORD
#define GUESSWORD
#include <string>
using namespace std;
[code].....
We can initialize normal function prototype's parameters with zero like this:-
void output(float = 0.0, int = 0);
or
void output(int = 0, int = 0, double = 0.0);
But how do you do the same for a pointer array or simply an array?
Assume that second parameter has to be an array.
I have tried the following and it does not work:-
void output(float = 0.0, int = 0);
void output(float = 0.0, *int = 0);
void output(float = 0.0, int* = 0);
void output(float = 0.0, int[] = 0);
void output(float = 0.0, int []);
But if I skip the default declarations altogether, it works.
like:
void output(float, int []);
or
void output(float, int*);
how can I do it by explicitly writing zero, just like the first cases?
I'm a newbie to C++ and I am writing a code that searches strings and checks their value. I'm mostly working with if statements.
My code tends crash on Dev C++, even when I haven't recently saved any changes or compiled it, citing "memory access errors".
I recompiled in visual studio, and visual studio told me I have string out of bound errors.
My code is very long... but most of it is copy and pasted with slightly different conditions.
I believe the problem lies in how I initialize arr[4] ??
#include <cstdlib>
#include <iostream>
#include <string>
#include <sstream>
using namespace std;
int main() {
cout << "Hall symbol -- generator matrix program" << endl;
// Setting up a data structure bc a normal array cannot handle the data for the spacegroups
[Code] ....
Need a C++ constructor to initialize each members of an array. how to give value for for each elements of an array declared as a class object according to the users input.
View 1 Replies View RelatedI somewhere read "You cannot initialize a structure like that at run time."
Example:
struct item_info {
char itemname[15];
int quantity;
float retail;
float wholesale;
[Code] ....
But if you want to assign values at run time then you have to do it manually like:
strcpy(item[0].itemname, "rice");
item[0].quantity = 10;
item[0].retail = 40;
item[0].wholesale = 30;
I tried in internet but am unable to know the differences. I want to know the difference between those two in terms of run time and compile time. Explanation required also for below one. Is this run time or compile time? How does we actually decide which is run time and which is compile time!
struct item_info {
char itemname[15];
int quantity;
float retail;
float wholesale;
//int quatityonorder;
[Code] ....
I've got an error saying that there is an access violation at 0x0000040 error no 0xC0000005
I've searched the net, saying the error may be due to an uninitialzed variable.I debugged the code, and found out that an object created from directx D3DXMATRIXA16 is uninitialized.With values ??,??,?? in each element
pMeshContainer->pBoneMatrices = new D3DXMATRIXA16[g_NumBoneMatricesMax];
here, pMeshContainer is a variable passed into a function called GenerateSkinnedMesh by pointer
GenerateSkinnedMesh(..., D3DXMESHCONTAINER_DERIVED *pMeshContainer)
Then in turn, GenerateSkinnedMesh is called within a callback from a DirectX9 API called
ID3DXAllocateHierarchy
Code:
class CAllocateHierarchy : public ID3DXAllocateHierarchy {
public:
STDMETHOD( CreateFrame )( THIS_ LPCSTR Name, LPD3DXFRAME *ppNewFrame );
STDMETHOD( CreateMeshContainer )( THIS_
LPCSTR Name,
[code]....
when the method CreateMeshContainer finished execution, the meshContainer is passed back to its parent like this
*ppMeshContainer = pMeshContainer;
The whole meshContainer stuff is stored persistently inside the frame root wrapped within a class called CMesh So in that process, I haven't initialized pBoneMatrices in anyways. But what and where is the best way to initialize an array of DirectX9 objects.
There is a function called
D3DXMatrixIdentity(&...);
But how can I initialize each one of them with this call?
Notice that pMeshContainer->pBoneMatrices does contain a valid address, despite the fact that the elements inside it are never initialized...
I have to write a program that selects a random color from an array. I used the srand (time(0)); statement but it still gives me the same color each time. Here is my code.
// Color.cpp
#include <ctime>
#include <iostream>
using namespace std;
#include <string>
#include <cstdlib>
#include "Color.h"
[Code] .....