Visual C++ :: Storing Some Variables In Disk?
Feb 9, 2014
I am using Visual C++ to write an app. One problem is that the application will allocate a lot of object instances of a specific class CMyObject, maybe 400, 000. This will cause "Out of memory" error when total allocated CMyObject reaches 400,000.
To solve this problem, I just wonder when a new CMyObject instance is created, is it possible to specify so that the instance will allocate on a disk cache, or file mapping instead of the memory space?
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Nov 23, 2014
Code:
_int64 free_space_64bit;
PULARGE_INTEGER lpFreeBytesAvailable, lpTotalNumberOfBytes,lpTotalNumberOfFreeBytes;
//char currentPath[MAX_PATH];
//GetCurrentDirectoryA(MAX_PATH, currentPath);
GetDiskFreeSpaceExA("H:C", lpFreeBytesAvailable, lpTotalNumberOfBytes,lpTotalNumberOfFreeBytes);
free_space_64bit = lpFreeBytesAvailable->HighPart << 32 | lpFreeBytesAvailable->LowPart;
This directory "H:C" does exist, if I comment out the GetDiskFreeSpaceExA line, the program doesn't crash, but it leads to some peculiar results (some uninitialized and random value, but at least it doesn't crash)
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Mar 16, 2015
how to read a csv file where the data is seperated with commas so the csv file looks like:
programming,03,60,141,01,W,2015
programming,03,60,141,30,W,2015
Algebra,03,62,102,02,S,2013
Religion,08,98,938,20,F,2014
So i need the name of the course in one variable, the course code (ex 0360-141-01 for line 1) in another variable and the term (ie W2015 for line1). So i got the name done but cant figure out the course code since i need more than one value that is seperated by a comma. my code is:
#include<stdio.h>
#include<string.h>
typedef struct CourseInfo {
int courseID;
[Code].....
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Jan 23, 2015
I'm trying to read in 3 values from the first line in a file. I want to take those 3 values and store them into 3 variables.
char buffer[100];
if((fgets(buffer, sizeof buffer, in) != NULL))
{
printf("current buffer is %s", buffer);
double tmpPrePrice, tmpDoorPrice;
int tmpTicCount;
int a = sscanf(buffer, "%d %d %d", &tmpPrePrice, &tmpDoorPrice, &tmpTicCount);
printf("applied %d variables %d %d %d", a, tmpPrePrice, tmpDoorPrice, tmpTicCount);
}
The input is
15 25 200
And the result:
current buffer is 15 25 200
applied 3 variables 15 0 25
any reason these aren't being stored properly?
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Jan 15, 2013
Opening large files in c++. In my application, i am trying to save video as long as users have space in harddisk. What I am trying to do is when user is recording video i am trying to append the video data in to the file. The problem is that every time file size reach over 2GB my software crashes.
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Nov 20, 2012
I am unable to understand why is the output for this shows me the address of the stored array.
int main()
{
size_t k= 0 ;
char t[3][100] = { "hi", "di", "fi" } ;
char s[3][100] ;
[Code]....
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Feb 12, 2014
I am trying to read and store a txt file with format below:
2.5;abc;2,4000
2.5;bef;3,2000
2.5;ref;3,1000
I try the fscanf( pFile, "%d;%s;%d,%d", buffer,buffer2,buffer3,buffer4 ); to store 2.5 to buffer, abc to buffer2, 2 to buffer 3 and 4000 to buffer 4 on first line.
However, it doesn't work. How can I achieve this? I want to read the 2nd line and so on.
Code:
char buffer[100]="";
char buffer2[100]="";
char buffer3[100]="";
char buffer4[100]="";
FILE * pFile=NULL;
pFile = fopen("C: est est.txt", "r");
[Code] ....
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Oct 9, 2014
In VC++ is there any inbuilt class for storying values inside an XML File, without using CLI?
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Aug 30, 2013
Any algorithm or function to rotate a displayed circle. To turn it 360 degrees like a car-tire. (It's needed to turn a turn-table in a model-railrod control program) .....
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Mar 30, 2014
I'm trying to write a program that writes data to a disk in C++ without caring about it's file system. Here is what I can do so far:
#include <iostream>
#include <unistd.h>
#include <fcntl.h>
using namespace std;
char buffer[] = "Wow! I'm writing this data to a disk without puttting it into a file!";
int main(){
int Disk=open("/dev/sdb",O_RDWR);
write(Disk,buffer,sizeof(buffer));
close(Disk);
return 0;}
But this program can only write ASCII characters to the disk. But what if I want to mainipulate bits on the disk, how would I do that?
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Dec 29, 2013
lets say I have a char array with four elements but only one char is used, does it write four elements or just one?
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Mar 3, 2014
When we are using RAM DISK - the files are stored on the RAM. From what I understand (and saw many examples) in order to read data from file (the file which locate on the RAM) - I need to use the read function.
Is there a chance to get char* (or any pointer) to the content of the file without using the read function ?
If the file locate on the RAM, it seem that it is like I have a buffer on the RAM (like an array which was dynamic allocated) and in the case of a buffer on the ram -> we can use pointers to the data without reading all the data.
example:
class CDATA {
int nValue1;
int nValue2;
double dValue3;
double dValue4;
char achBuf[10];
[Code] .....
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Oct 1, 2013
So this code compiles without any problem but it is not producing the correct output. I know there's a problem in either my getBlock or putBlock functions but I can't see it.
Currently the output is "Should be 32 1s: "
"Should be 32 2s: "
There should be 32 1s and 32 2s and nothing is coming out.
#include <iostream>
#include <fstream>
using namespace std;
class Sdisk {
public :
Sdisk(string diskname);
[Code] .....
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Sep 12, 2013
I made a text file. I can do all File I/O functions in c. no problem! except that "I want to get the memory address of the beginning of that File", so that I can access each character of the file by incrementing memory address.
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Apr 21, 2012
Basically, I want to write an image to disk in parallel with an algorithm that is processing that same image. The code is really simple:
Code:
string ProcessImage(System::Drawing::Bitmap ^bmp, System::String^ targetFile) {
bmp->Save(targetFile);
System::Drawing::Bitmap^ bmp8 = BitmapConvertPixelFormat(bmp, 8); //<-- a function I wrote which converts the 32bpp I am passed into an 8bpp one
string results = Analyze(bmp8); //<--- takes a good bit of time
return results;
}
What would be the fastest way to do this? Any libraries with a code sample. I would prefer one that is within .NET or native C++ just to avoid having to link into many different libraries.
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May 26, 2013
Here is a working C++ program and its output that reads the names of a certain number of functions whose names are written in a disk file that provides the control parameters in a near-real time fashion. Based on this information, the program calls those functions whose names were given in this text file as parameters. The method I have used is to build a map of functions that connects the names of the functions to the actual functions. Once this map is created, then it is very easy to iterate in such a way that only those selected functions are called.
So far this is working well, and it makes the logic of the code easier because ultimately there will be a large inventory of functions (probably hundreds of functions), and this way of pre-building a map of functions avoids writing hundreds of if statements in the code. Of course, pre-building this reusable map in the background is still equivalent to writing that many if statements, but at least it makes the code very compact and much more automatic, since it is done only once.
But I now have a related question: In this case (when the selected subset of functions to call is given as incoming data as in this example), does C++ make it possible to avoid using maps of functions, by directly applying the string variable that holds the name of the function in order to call the original function immediately For instance, if a string variable s = "MyFunction", then is there a more direct way of using this string as if it were the actual function whose name is spelled exactly in that way? This would make the code even more compact.
Here is the sample test code for the map of functions, and its output:
First of all here is the text file "FileForNamesOfFunctions.TXT" that contains the part of the "data", which is the set of functions select from from the inventory and only call these:
Code:
function2
function3
function5 And here is the C++ code that uses this "data":
Code:
#include <fstream>
#include <iostream>
#include <sstream>
#include <string>
#include <vector>
[Code] ....
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Jul 19, 2013
I'm trying to create an executable with C or C++ that send a command with the function system, but it waits for a command or key.
Example :
I send this:
C:
unas /noprofile user:administrator notepad.exe
But it waits for password.
Please type the password :
So my question is how can I make to send the password or that my program detect that prompt.
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Oct 13, 2014
In the following code I want to iterate through "Win32_OperatingSystem" to find all variables and their values. Using GetNames() I can get the names of all the variables but the subsequent Get() call fails to return a value.
Code:
//connect to WMI
std::wstring wmiClass = L"Win32_OperatingSystem";
CComPtr< IWbemLocator > pLocator;
HRESULT hResult = pLocator.CoCreateInstance( CLSID_WbemAdministrativeLocator, nullptr, CLSCTX_INPROC_SERVER );
if ( SUCCEEDED( hResult ) )
[Code] ....
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Apr 8, 2015
C++
Create a Triangle class that has the following member variables:
side1 - a double
side2 - a double
side 3 - a double perimeter area
The class should have the following member functions:
- default constructor that sets the value of all 3 sides of a triangle to 0.0
- a constructor with arguments that accepts values for the three sides of a triangle (member variables) as arguments
- setDimensions - a function that allows the value of the three sides to be entered by the user through the keyboard
- testSides - a function that determines if the 3 values entered can actually be the sides of a triangle. If they do not create a triangle, print the values entered and an appropriate message
--The sum of any two side lengths of a triangle must always be greater than the length of the third side: so side 1 + side 2 > side 3 and side 1 + side 3 > side 2 and side 2 + side 3 > side 1 ( all three must be true for the 3 values to make a triangle)
- getSide1 - a function that returns the value of side 1, getSide2 - a function that returns the value of side 2, getSide3 - a function that returns the value of side 3
- getArea - a function that returns the area of a triangle: The formula for the area of a triangle (when the height is not known) is: A = sqrt (p(p-side1)(p-side2)(p-side3)) where p = (side1+side2+side3)/2
- getPerimeter - a function that returns the perimeter of a triangle: Perimeter = side1 + side2+ Side 3
- A displayTriangleInfo function that displays side1, side2, side3, area, and perimeter for a triangle object.
After testing your code for a single object, create an array of 5 triangles. Use a for loop and the setDimensions function to allow the user to set the values for the 3 sides of a triangle, test the vales entered to determine if the 3 create a triangle. If they do create a triangle than use the getArea and getPerimeter functions to calculate the Area and Perimeter for the triangle and use the displayTriangleInfo function to display all of the data for that triangle. If the three values do not create a triangle then print the 3 numbers entered and an appropriate message. In either case the loop should then move on and get the data for the next triangle from the user.
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Oct 18, 2014
I just started programming and want to make the game cows and bulls. The problem is that after the loop has ended and both vectors are not the same I want the user to 're-input' the starting variables a,b,c&d but I don't know how to.
Code:
#include "std_lib_facilities.h"
int comparison(int a, int b, int c, int d)
{
vector<int>bc={ 1, 2, 4, 9 };
[Code].....
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Mar 10, 2014
I came across the following code today and I was a bit surprised that it worked:-
Code:
std::string func_A () {
static std::string x;
if (!x.empty())
return x;
[Code] ....
I've simplified things slightly - but the basic point is that both functions are in the same source file and they both have a static std::string called 'x'. Being static, I guess they aren't (strictly) local variables. So how does the compiler know that they're different entities? Does it encode their signatures using the function name or something like that? If I call each function separately I do seem to get the correct string...
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Sep 30, 2014
I have created a windows form project in visual studio so that I can use a windows form to interact with the game class that I'm creating, but I'm running into some problems.
For one thing, I would like to be able to call Image::FromFile() one time only during initialization, and store the result in a member variable (called mBGImage). From what I can tell, the variable needs to be of type String^ (this caret symbol is new to me, but I understand it is the "managed code" version of the standard pointer, which would look like String*).
When I try to compile the following code (located in my header file) I get the error :
"error C3265: cannot declare a managed 'mBGImage' in an unmanaged 'BSG::BSGame'".
How can I store the result of Image::FromFile() permanently in my class?
When I try to declare a global variable of type "Image^", I get "error C3145: global or static variable may not have managed type System:rawing::Image ^"
#include "stdafx.h"
using namespace System;
using namespace System::ComponentModel;
using namespace System::Collections;
using namespace System::Windows::Forms;
[Code] ......
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Sep 8, 2014
I am new to VC++ 2012. I have this code snippet.
Code:
auto it = query_map.find(U("callback"));
The problem is right under the dot there is a red line the error is
Error1error C2664: 'std::_Tree_iterator<_Mytree> std::_Tree<_Traits>::find(const http::uri::encoded_string &)' : cannot convert parameter 1 from 'const wchar_t [9]' to 'const http::uri::encoded_string &'d:maverickprojectsstrikeforcesrcserverserverserver.cpp26
What is the solution to this error?
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Jul 31, 2013
I have written a class "FileSet " in program's Document class.
This class contains other Four classes as
"Machine1" , "Machine2", "Machine 3" and "Machine 4".
Now my problem is Machine 1 can not access variables from Document class or other variables from FileSet.
How to access them ?
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Jul 19, 2013
I have a main dialog which has (DDX?) controls for the user. eg a slider, and a combo box.
Previously, an image adjusted by these controls was in the same dialog.
I need to put this image in a New, separate dialog but it still must be controlled by the slider and combo box on the main dialog.
My question is how can I pass the control's variables between the dialogs? I have, say,
Code:
//MainDlg.cpp
DDX_Control(pDX, IDC_ComboBrightness, m_Brightness
I was told that I could do something like:
Code:
//ImageDlg.h
public:
ImageDlg(CWnd* pParent = NULL, CComboBox m_Brightness); // standard constructor
But I get errors including: Missing default parameter for parameter 2
I also need to pass the image array, is that perhaps the same method?
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Mar 26, 2013
I have a project to do in C and coming form Java I miss all the included features that are missing from C! I need to be able to store key value pairs in an quick and memory efficient manner. I've looked up using hash maps but I'm very new to C so don't really understand even the basic ones. I've looked at using a multi-dimensional array as I'm more comfortable with arrays but I'm unsure if that would count as a memory efficient and quick method?
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