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 have array of 100 elements and I'm trying to write elements which index is smaller than the index of the maximum element of the array. My problem is that I can't determine how big this array should be . I found which is my biggest index.
Code:
#include <visual_2013.h> #include <stdio.h> #include <stdlib.h> #define DIM 10 void enterArray(int x[]); void array2(int x[]); int maxAndIndex(int x[], int n, int *index); int main()
I'm working on a piece of code written long time ago. Without getting in the details or too much context here, there is a function that declares an array of char of a size of 350,000 elements, in order to fill it (using a pointer) with the list of all running processes on the machine (using "ps -ejf" on a Linux box).
The size of the char array has been changed from 40,000 to 350,000 sometime along the years, probably because of a lack of space required.
What kind on data structure / storage would you use to store the running processes in order to eventually search for a value in it?
Say I have a class with a few member functions, and only two data members: an int* Table; and an int Size;, to store the number of elements in Table.
I'm using a copy constructor that takes in two parameters: int* table, int size. In this case, is the address that table points to the same address as the object that table is part of? And furthermore, is it possible to say table.Size? I want to compare the passed array's size to the passed size.
Dynamic memory allocation in array in c programming. I am trying to make the user to choose the size of array they want to engage in the game.
However, i have remove the global variable which contribute the error to my code previously. Now I assigned all the arr individually but not using the global variable. However, i still not get the desired board i want. i still keep getting 9x9 array board.
And i also need limit the board size only from 4 to 9. And how do i do that.
I'm writing a program with a class containing a private std::vector<bool>. I chose bool because the vector represents a 2D array (think grid) and I only need 2 states per cell. I kept it one-dimensional as this hardly complicates things.
My problem is that I don't know how to initialize the vector, i.e. fill it with 0's.
The grid's resolution is not known at compile time, so I imagine I have to set the size (and content) of the vector in the class constructor.
Here's what I have tried among several things:
Code: World::World(const u_short worldsize) { grid.reserve(worldsize * worldsize); // grid is the private vector; square dimensions. std::fill(grid.begin(), grid.end(), 0); std::cout << grid.size(); } The output is 0. Only std::vector::push_back seems to have an effect on size(), but judging by its description, it doesn't look like the right candidate to populate a vector with zeros. Correct me if I'm wrong.
Frankly I expected line 3 to set the vector's size.
I have a program which call only one time malloc at the start of the program. When running, I see with 'process-explorer.exe' that memory is growing in little steps. Is this normal? why?
I'm trying to keep track of the size of blocks of memory that a pointer points to. No matter what I do, this code below always outputs the integer 8.
If I change 1000 to 5, I still get 8. If I change it to 0, I get 8... If I change it to -1, I get 8. If I change int *a to double *a, I get 8. If I take away the & symbol, I get 8. If I use *& instead, I get 8.
Why? I want it to output 1000. If I change that to 500, I want it to output 500.
int *a; a = malloc(1000 * sizeof(int));
int j = sizeof(&a); printf("%d", j);
I want to build my skills where I can allocate, inspect and change memory sizes.
Why the size of a process grows larger in size for lots of small memory allocations. For example, say I have this struct, which is 16 bytes (for a 32 bit build):
Code: struct Person { int iID; int iAge; char * pForeName; char * pSurName; };
If I allocate memory like this:
Code: LPBYTE lpB = new BYTE[sizeof(Person) * 1000000];
Then my process grows to 16,48KB in size, which is what I expected. However if I allocate memory like this:
Code: Person * lpPerson; for(int i = 0; i < 1000000; ++i) lpPerson = new Person;
Then the process grows to 78,656KB, which I don't understand.
Additionally, I was surprised to find a vector acts more similarly to the first example. This code:
Code: Person temp = { 0 }; std::vector<Person> people; for(int i = 0; i < 1000000; ++i) people.push_back(temp);
I am currently trying to implement a 2d vector to store x and y of type int.
I have successfully passed it to the function, however i am unable to store the values in it. It always returns with a segmentation fault and my program terminates from there. May i know how do i store them properly and call them out?
Below is my code snippet
int reconstructSecret(int x, int y, vector< vector<int> > &inVec ,int constructSecret) { int getX,getY,formula,accum,count,getSecret,startPosition,nextPosition,numerator,denominator; getX=x; getY=y; int result;
[Code] .....
The main method
vector< vector<int> > inVec; for(int i=0;i<constructSecret;i++) { cout<<"please key in the "<<i<< "share of x value:"; cin>>x;
I am working on a project for class where I use a parent Shape class with circle, rectangle, ect. Classes inheriting from that. Along side these I use a class called Scene. In main I need to create a scene and add some shapes to a vector in scene.
vector<Shape*> shapes
I need to use functions addShape(Shape* shape) and a delete shape method. I have the addShape finished. The problem I am having is with the delete method. Is there a way that I can use something like deleteShape(Shape* shape)? Is it possible for me to delete a specific shape from the vector by passing in that shape, or can it only be done using index? I have looked at the documentation for std::vector as well as std::vector::erase. I am wondering this because if I use index values and do something like
void Scene::deleteShape(unsigned int x) { shapes.erase(shapes.begin() + x ); }
It will lead to some errors later on due the the changing size and indexes of the vector and elements.
"Write a declaration for a function that takes two int parameters and returns an int, and declare a vector whose elements have this function pointer type."
I think std::copy appears to do what I'm looking for.
I'm in need of a vector member function that would allow me to "insert" a number of elements from one vector into another vector without resizing or destroying either.
An example of what I'm wanting to do is assign the contents of two[3-5][50-54] to one[7-9][2-6]. Other than looping through both vectors using .at(), is there a way to copy this?
This would be continuous within a user controlled loop with differing elements being exchanged.
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'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?
I am trying to allocate a memory to vector but while running the program,my window appear and PC get halt state then i have to force fully shutdown my PC I found that due to the vector i am getting this problem.
I have read that the Erase-remove idiom is the way to go. I have a rough understanding of how this works but am unsure whether I can implement a match-counter along with it.
For counting alone, I would use something like this:
Code: std::vector<std::string> v; // contains duplicate strings in different elements std::string term = "foo"; // search term, changing at runtime as well
unsigned int matches = 0; for( auto e : v ) { if( e == term ) {
[Code] .....
I'm not sure how (or if) I can combine the two things. That is, I don't know how to integrate a function comparing two (changing) strings into the remove_if() method. Nor do I know how to increment a counter during iteration.
The vector is extremely large, so speed is paramount. I think there are many other avenues for optimization, but decreasing the vector's size for each consecutive search could deliver a big speed boost for subsequent searches I imagine, as traversing it holds the biggest cost.
I 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.
