C++ :: How To Store Variable In Memory When Program Is Closed
Nov 3, 2013
How do you store a variable in memory so that it isn't changed when the program closes? I don't have any experience with this and am just wondering how it is possible. I am creating a program and want it to store your preferences and scores. In a simple program, everything is just reset and I don't want this for my program. How do I store a variable so that it stays the same, but can be changed even when the program is turned off?
I got an assignment at school asking for a program that can implement functions that store, get and deletes text/binary data to a given memory area. We are supposed to make kind of like a tiny-mini OS..any links to some tutorials or explanations hon ow to understand this and be able to make a program like this on my own?
I am having trouble compiling my interface. I am trying to store a reference variable as a member variable of the interface object. Compiler says that the variable has not be initiated correctly.
LCD inherits from VisualInterface which is expecting a DisplayDriver object to be passed in (DisplayDriver is another interface, but thats not important).
I pass the displayDriver object in when LCD is instantiated in maininterfaces.zip
I was pasing it before as a pointer but was told that this could cause me problems with memory leaks and a reference was better, but now I cant seem to get it to compile.
I want to store few different functions to a variable for different structs/classes and then call it later using that variable, is it possible? something like
struct item { int ID; int special; // for function };
item Key; Key.special = UseKey(KEY_KING);
// now when I want to call function "UseKey(KEY_KING)" I want to use "Key.special", like this
I have one requirement to store an array of structure at shared memory. Also the shared memory should have one counter to store number of elements in the array.
I tried to look at some placed but didn't find anything relevant.
So my first question, is it possible that we can store two things on same shared memory. And second if not then how to achieve the same?
I serialize a XML file, and i have this values here:
public class ServiceConfig { public List<DatabaseDescriptor> Databases { get; set; } } public class DatabaseDescriptor { [XmlElement("Name")]
[Code] ....
I have a form1 which is a datagrid view and get's updated like this:
dataGridView1.DataSource = xmlData.Databases;
Now i have a button: get tables, and it opens up form 2, there it's supposed to appear all the tables of the selected Database, when i click on the row i get the database name so i get all the list of Tables from
DatabaseDescriptor where DatabaseDescriptor.Name == name (I get this when i select the row)
But then on the 2nd form, i also have 2 textbox so i add a new table, i add the tablename and id. the new value should appear in the datagridview of the tables, and when i close it and reopen it, it should be there. Maybe i should concatenate first the values or something, how do i do?
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.
Im trying to write a program that reads in strings and decides if the 1st one is repeated. I cant figure out how to store the first string into a variable, and compare that variable to the rest of the inputted strings.
Code:
#include <strings.h> #include <stdio.h> int main () { //Declared variables int i; }
Is it even possible to store the 100th Fibonacci number (beginning with the numbers 1 and 1) into a variable? I know the number is pretty huge, and wondered if there is a data type to hold a number that big.
I would like to store the entire content of a file in a single c-string variable or in a standard string class variable. Is there a function that will do this for me? I am familiar with functions that get one character or one line at a time but I don't think I've encountered a function that gets the entire file. Does this function keep or disregard the end-of-line character? If no such function exists, I would write my own function to create and return such a variable.
I've been trying to store the inital size of a list in an int variable, so I can access it later in case I modify the list size. For example, I did the following:
std::list<AType *> myList; myList.push_back(anATypeobject); int initListSize = myList.size(); //initial list size myList.push_back(anotherATypeobject); myList.push_back(yetanotherATypeobject); while(myList.size > initListSize) myList.pop_back();
What this is supposed to do is to get an initial size of a list, and then be able to return to that initial size. However, when I try to do it in my code, initListSize always change if myList.size() changes. Is there a way to change that?
5502 5202.3 1523 2536.1 1254 1256.2 17846 8956.2 and so on
left one is time and right one is pressure, I need to show the time value as it is but i need to use the pressure value to calculate air speed. I don't know how to use the strings to pick up the list properly. I did the calculation formula for the air speed but i can't pick the pressure value up from the text file. here's what i did:
#include <iostream> #include <fstream> #include <string> using namespace std;
My program is designed to read input from the user and then store that input in a structure variable. Whenever i use the cin.getline() function, it comes up with a semantic issue. Here is the code:
I need to average integer measuring samples and store this variable, so that it can`t be changed.
I need to get the initial pressure reading from my bmp085 pressure sensor, an integer value between 0 and 10000 and store the initial value after program start, so I can compare the later readings to determine whether pressure went down or up. The value to store should also be integer, rounding errors don`t matter.
I am trying to make a function that allows me to allocate memory to a "mem" variable and setting each of its chunk's status to FREE. FREE is defined as 0. Below is my code of the function.
Code:
int allocate(mem *mm, int num_chunks, int chunk_size) { int i; mem *temp; if((mm = (mem *) malloc((num_chunks + 1) * chunk_size)) == NULL){ perror("Failed to Malloc
[code]...
mem; If my function works the way it should, it should print out five 0 because that is how I set them in the function, but this is not the case. I've looked at my function for 2 hours, but I could not figure out any logical error. Now, I think my problem lies with my limited knowledge of pointer arithmetic. On the other hand, when I insert 1000 as the second argument into my function, it gives seg faults, which is not the case for smaller values like 5, 10, 15, etc.
So, I've made programs like Prime number searchers and such. But the problem is if I use an int or long int variable for the program I am limited by the variable size. I can't search through numbers larger than their memory size. So my question is: Is there a way to allocate memory to a single variable, NOT AN ARRAY, so I can make a variable as many bytes as I want?
I created a class (let call it X) which contains the structure to store the data from my data base. Them I have a class (call Y) which will contain a list for each row in my data base. Third, I have a class with thousands variables (Z). What I am trying to do is to take the list of objects (Y) that contains the data to initialize Z. What I want to now if I can do something like that.
Imaging that one of my rows contain the following data: Type Nameofvariable etc... "static const double; MNFAIL ; 0; 0; 0,25"
In my list I have a node with contain this data
I want to use the field Nameofvariable to initialize the variable called MNFAIL contained in my class Z.
I want to store values permanently in a variable. The same variable should be able to be edited and saved by user, and whatever it is I need the value of the variable from the last time I modified it, like a database. database because i need this to set my connection string of the database.
This does not allow me to initialize _listRef as something like NULL when it is not applicable.Also, i must change all my constructors and its child class to include an initialization of _listRef!!
What is the alternative? Is pointer the nearest? which of the following should be used?
Code: const QList<QSharedPointer<Data>> * _listRef; or const QList<QSharedPointer<Data>> *const _listRef; or const QSharedPointer<QList<QSharedPointer<Data>>> _listRef; ????
I want to store the address of a customer (with spaces) in a char variable (say cadd). First I tried to use "cin", as we know it reads until it sees any whitespace. So it reads only first word before a white space. So, I used "getline()" function, it will work. But when I used it, It did'nt wait for the I/P (it skipped it).
recently I developed a class header only in C++ to deal with byte arrays. Since I developed programs in other languages that had some libraries to dial with byte arrays, I developed one that the syntax is very similar to other languages.
Since I'm not very familiar with memory management, I was concerned about somethings I've read about (ex: memory fragmentation).
The class is intended to be used as part of comunication protocol in a webserver, byte arrays are created and destroyed a lot. Should I use pools? Is there a better practice? Am I doing everything wrong (laugh)?
For those who wants to see the entire class: [URL]
