How do you write your own Filesystem/Format?
I've always wanted to know how to write my own system for the learning experience. I've worked on simple ones that read from a flatfile of a defined size, but never one that was on a fully formatted drive.
Where do I start? Are there any examples/tutorials?
Development of a custom binary file type? So far all I know is the just the basic structures of the binary file type, I know that structures are involved but the implementation part I have run into walls.
View 1 Replies View RelatedDoes the requirements have changed for writing custom allocators with C++ 0x11?
A custom allocator (that uses a fixed array as its memory pool) that I have been using successfully for some time, now throws an exception!
It runs fine under VS2008 but bombs out with VS2010.
I wanna write a piece of code in C++ that extract the width and height of a image with bmp file format...
View 2 Replies View RelatedI am trying to write down in binary format an array of unsigned int values but i get the following compilation error :
: In function ‘int CIndex(std::fstream&, std::fstream&, std::fstream&, std::fstream&)’:
./src/IndexBuilder/index.cpp:23:26: error: no matching function for call to ‘std::basic_fstream<char>::write(int*, long unsigned int)’
./src/IndexBuilder/index.cpp:23:26: note: candidate is:
/usr/include/c++/4.6/bits/ostream.tcc:184:5: note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::write(const _CharT*, std::streamsize) [with _CharT = char, _Traits = std::char_traits<char>, std::streamsize = long int]
This is the part the is not working:
Code:
// uia is : unsigned int * uia;
// then I have allocated the space for it
// load it with unsigned int's
// k is the number of variables in my array
o.write(uia,sizeof(unsigned int)*k); But thsi should be so simple and strait forward.... in c i do it as :
Code:
fwrite(uia, sizeof(unsigned int), k , fp); but since i would need to convert fstream to FILE* i decided to do it c++ way.
and this is how i opened the file :
Code:
o.open (fileName.c_str(),std::ios::out|std::ios::binary);
I have one problem deleting a file with boost. The file is opened in another application and cannot be deleted. I am supposed to received an exception error but I don't get it.
Here is my piece of code, very simple:
bool delete_file(const string &path) {
boost::filesystem::path bpath(path);
try {
if (boost::filesystem::remove(bath)) return true;
[Code] ....
I have put a breakpoint inside the catch part but it does not come to this point. Instead, the the output window of visual studio, I got these lines:
First-chance exception at 0x00007FFD2E575A88 in site_server.exe: Microsoft C++ exception: boost::filesystem::filesystem_error at memory location 0x00000070F8E3E920.
Unhandled exception at at 0x00007FFD2E575A88 in site_server.exe: Microsoft C++ exception: boost::filesystem::filesystem_error at memory location 0x00000070F8E3E920.
How to manage this situation?
I have the following code which is based of the tut3.cpp example at: [URL] ....
However, I'm not entirely sure how to retrieve the full file path which I'd like to use to get the file size. So essentially the aim is to go through a directory and list all the file sizes.
Code:
if (exists(p)) {
if (is_directory(p)) {
cout << p << " is a directory containing:
";
copy(directory_iterator(p), directory_iterator(), // directory_iterator::value_type
[Code] ....
I'm trying to write a custom allocator that I can use with the STL. Here's what I have so far :
Code:
#include <cstddef>
#include <iostream>
#include <memory>
#include <vector>
template<class T>
struct customallocator {
[Code].....
I'm doing and currently, my push_back doesn't seem to do anything.
Let's say we have a custom Vector class and I need to know which of the following is considered to be more efficient and why of course.
Vector Vector::operator+(const Vector &b) const {
return Vector(x+b.x,y+b.y);
}
Vector Vector::operator+(const Vector &b) const {
Vector tmp(x+b.x,y+b.y);
return tmp;
}
I've written a doubly linked list per my assignment instructions. I've implemented begin() and end() iterators for it, and they work with no problems when traversing the list. However, I need to sort the elements in the list. We are allowed to use the sort function defined in the <algorithm> header since we haven't yet covered sorting algorithms.
But, I'm running into a ton of problems. I figured as long as the begin() and end() iterators were defined for the list, then sort(list.begin(), list.end(), compare) would do the trick. The main errors I'm getting are:
error: no type named iterator_category
error: no type named value_type
error: no type named difference_type
error: no type named pointer
error: no type named reference
And also errors for no match of the + and - operators for the iterator class.
I understand reference, pointer, and value_type, but I have no idea about iterator_category and difference_type. Additionally, I'm a little unsure why the + and - operators need to be overloaded.
I have a POPUP
MAIN_MENU MENU {
POPUP "&Manager" {
MENUITEM "New Royal Python", MENU_NEW_ROYAL_PYTHON
POPUP "&Select Python" {
}
}
}
I basically want to give the POPUP an ID so I can talk with it but it does not seem to be accepting a second parameter. Once I have done that I need to send a message to it to ask it to add a new item, what are the messages I need to send for this?
I am making a level editor that needs to output a custom map file for use with source code that I will write for a graphics library.
My question is: What do I need to bear in mind when deciding how to structure a custom file type? Also how can I encode a standard bitmap image into my file (the tile set) so that it can all be contained in a single file rather two files; the map file and tile set (.bmp file).
I have begun switching from WinForms to WPF and I'm having a hard time understanding the new concepts. In WinForms, I had a few User Controls, custom drawn using shapes (rectangles, ellipses, etc). They had some unique properties, like "Flashing" (setting this property to True and setting the "Flash Interval" property to 500 would have resulted in the control changing its background color to white and back again, every 0.5 seconds), "Beeping", etc.
I have tried to replicate these controls in WPF/XAML and so far managed to draw the shape. However, when it came to implementing a custom property that would redraw the background color of the rectangle every interval set by user in another property, i got stuck. The property is being set, but it doesn't change the background color. Alternatively, i have tried this method, with the same results (i got it to show in the "Properties" window in Visual Studio, i can set it, it is being stored in XAML, but it doesn't affect the background.
C# code behind:
public struct LCARSColors
{
public static Brush DarkBlue = (Brush)(new BrushConverter().ConvertFrom("#FF3366CC"));
public static Brush LightBlue = (Brush)(new BrushConverter().ConvertFrom("#FF99CCFF"));
public static Brush Pink = (Brush)(new BrushConverter().ConvertFrom("#FFCC99CC"));
[Code] ....
If i use this line (commented in this code sample):
<!--<SolidColorBrush x:Name="MySolidColorBrush" Color="{DynamicResource DarkBlue}" />-->
The background is colored in DarkBlue (as defined). But if i use this line:
<SolidColorBrush x:Name="MySolidColorBrush" Color="{Binding BackgroundColor, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}" />
Nothing happens, the rectangle disappears entirely. If i add this to the above line:
FallbackValue=LightYellow
The rectangle is colored in LightYellow, meaning that the property is not accepted and the fallback value is used. Why?
I've done some research and found that people use Mah metro, though I don't want to use that because I want to make a GUI that is fully mine, so I can do what ever I want to customize it to my liking.
I don't know how to get this done in WinForms....
I was going through tutorial in WPF on customs Cursor, While Running the application i am getting an exception XamlParseException was unhandled, here the code
public partial class MainWindow : Window
{
public MainWindow()
{
[Code].....
I have been trying to make a custom control(list box with more features). I know how to setup custom properties, but how do I make it so that the property can be edited in a separate window ?
I think I figured out how to show the form itself, and I don't know how to make the [...] button like :
There's not much Custom Control tutorials out there, and that's really the problem here.
I am new to application coding as I previously coded Python. XAML. How to use a custom image I made as a background image in my program. I have searched everywhere but all there is about how to use the asset images.
View 2 Replies View Relatedso i have a std::map like this:
map<DWORD,DWORD> mymap;
now i want to sort it by the second DWORD value, and thus i have to implement my own comparison function and use sort() from <alogirthm>:
Code:
bool y(const map<DWORD,DWORD>::iterator& a, const map<DWORD,DWORD>::iterator& b)
{
if(a->second < b->second)
return 1;
else
return 0;
}
...
sort(mymap.begin(), mymap.end(),y);
...
but this throws thousands of errors at me, including C2784.
I've been pondering which of these 2 approaches would make for the best interface for a library: Defining custom exceptions with specific names for different error scenarios but with standard behaviour, or simply using the predefined exceptions from the STL.
This is my current approach:
Code:
namespace rpp
{
class ConnectionError : public std::exception
{
public:
ConnectionError(const std::string &p_err);
[Code] .....
This seems to make for more descriptive code but it adds no functionality and the implementations are completely identical, which seems "off" to me, somehow.
I want to create an unsigned arithmetic type that can hold a maximum size of 360. Without having to create a method.
It should be in such a manner that:
Code:
typedef uint8_t radius;
radius rotation = 0;
radius foo (radius rotation)
{ return --rotation;
}
returns 359, instead of 255, or 65535 or whatever max value the type I base my type on can hold.
When we want to use custom classes for the STL set data structure, how to do it?
I look around and see people passing comparators, overloading operator(), and also overloading operator< in the class itself.
Which one's the idiomatic c++ way?
I am creating a special struct with unknown functions. I use this approach:
Callbacks.h Code: #ifndef CALLBACKS
#define CALLBACKS
struct Callbacks;
struct Callbacks* getNewCallback();
[Code]....
When I ran it only the calls from doers array is called 7 times normally, and donters only one time. Why is that? When I call doers from the second loop, it prints the doers functions again....and only one call to donters is made to the first static inline donter functions __dont1()...
I'm working on a code for ascertaining the minimum penalty of an assignment problem. The basic complication of my code is this: I have a vector of objects of a custom struct. The struct has a member, which is an integer. I need to keep the vector sorted according to that member, even when objects are added to or deleted from the vector. To illustrate the problem, I'll give an example.
Code:
typedef struct examplestruct{int i;
char c;
...} es;
int function(void)
{vector<es> ObjectTable;
//insert an object so that the vector remains sorted according to i
insertobject( newobject, &ObjectTable);
//deleting the top element of the vector
deleteobject(&ObjectTable);
return 0;}
I have tried to do it using bubblesort. But it's too slow. How to make a heap out of it.
The detailed premises of the problem is this: There are a number of jobs, and with each job a completion time and a cost coefficient. We are to ascertain the optimal sequence of jobs for which the penalty is minimum. Now, suppose we are given jobs A, B, C, D and E. We find out the lower bound of penalties for all the jobs.
Suppose we find B has the lowest penalty. Then we find out the lower bound of penalties for BA, BC, BD and BE. We continue this until we have the best value and a complete sequence. The way I have implemented this in a code: I have created two structs. One is Job, with the completion time and cost coefficient as members. The other is Node. Nodes have a Job Array and a Penalty as members. Now, we have a vector of Nodes which we need to keep sorted according to the penalty. We need to insert new Nodes and delete the expanded Nodes.
I have included my code. The pushInTable function inserts the new Nodes in a sorted vector. But it slows down remarkably when we give more than 20 jobs as input.
I'm trying to make a windows-focused , I will make it portable after , audio function that plays sounds according to my midi file. I know there is playsound, but it's not what I desire. I'm curious if Beep plays through the sound card or is similar to printf("a") ? I'm just looking for a low level solution.
View 1 Replies View RelatedI am currently working on a custom "Array" class for a project, and I have run into an error I don't quite understand the source of. The relevant code is as follows:
template<typename T> class Array {
private:
T errValCopy;
public:
T __errVal__;
uint16 __size__;
T* __ptr__;
Array(const T& errorValue);
[Code] ....
When I try to run the following code:
Array<Array<int>> a(Array<int>(-1));
The error log tells me there is no appropriate default constructor available. If I understand it correctly, "default constructor" refers to the constructor which lets you just write Array<int> a; instead of Array<int> a(...);, but I can't see where in the code such a situation occurs...
I've been working on a project for a few days now, and within this project I need to have a class system that can function similarly to an if statement. The problem I'm having is I can't seem to find any good information on the order in which if statements process the information within it. I understand that if statements process whatever's in parenthesis first, but my question is that when their are several booleans of equal value, for example: "if(x == 1 && y == 2 || 3 == 4 && 4==6)", in what order does it process these true or false statements? (The actual content of the example is superfluous).
View 2 Replies View Related