C++ :: Sharing Data Between 2 Files
Aug 30, 2013
The problem is I have a function which sets some variables and I want to access the variables, but myfunc() is nested too deeply for me to pass a data structure all the way down and to return all the way up. The functions reside in different files. I'm not allowed to use extern structs (i.e. a global variable).
How to use a class and instantiate it in myfunc(). My solutions are:
- using the singleton class method
- static variables and function residing in the class (but I'm suspicious of this way. seems like it's just class variables masquerading as global variables.
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May 22, 2013
I am just wondering if it is possible to send a project to someone via email - In a simple way, almost like you would install software from the internet, maybe a setup file, or something. The compiler I use "Dev C++" creates a .cpp file and an executable. Unfortunately, I cannot send that .exe file. How would you recommend sharing a program?
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Apr 5, 2013
I am writing a program to hide files behind other files using Alternate Data Streams in Windows NTFS file systems.
The program is as follows:
Code:
#include <stdio.h>
#include <stdlib.h>
int main(void){
char hostfile[75], hiddenfile[75], hiddenFileName[15] ;
printf("Enter the name(with extension) and path of the file whose behind you want to hide another file: ");
scanf("%75s", hostfile);
[Code]...
The complier is showing error as "Extra Perimeter in call to system" but I am not getting where?
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Jul 10, 2013
I have written the following code to add data to text files which are required to store 3D scan data (I have to calculate the y-coordinate). My code seems to work except that it stops working when I want to create more than ten text files i.e. the directory I am trying to store them in will not hold any more than ten text files. Code is shown below.
#include <string>
#include <locale>
#include <iomanip>
#include <iostream>
#include <fstream>
#include <sstream>
using namespace std;
[Code] ....
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Nov 9, 2013
So, as the title says, I'm trying to eliminate false sharing, or, eliminate sharing writes between threads with TBB. The question is how.
Normally I'd make an array whose size is equal to the number of threads, then locally write to a local variable and update the array only at the end of the thread.
But, of course, I cannot seem to get either thread id or total number of threads TBB uses. I found a reference to tbb::enumerable_thread_specific, which as I understand, is supposed to work for exactly this. But as soon as I added it, it hurt performance by ~60% instead of making it better.
How to do this properly? You don't really need to look so hard on how the algorithm works (I don't know either). I know it's not quite right right now due to race conditions, but I'll fix that later. I used a reference implementation that I copied™, and my task is to parallelize it.
The parts where the problem is right now is in red (of course, it's not all problems; it's only a subset of them).
Code:
#include <iostream>
#include <vector>
#include <fstream>
#include <ctime>
#include <algorithm>
[Code] ....
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Mar 16, 2014
my goal:
have 1 program handle the UI
have that program store variables to a DLL
have the 2nd program grab the stored variables to reform some number crunching, without interfering with the UI program, and once done, have it drop the answers back into that DLL, so that the UI can grab it when it's ready.
I have made the 2 programs, + dll
What I've Achieved:
the first program accesses the dll, and loads up a variable (and stays connected to the dll, so that the Dll instance doesn't reset)
I've gotten the DLL to output the variable to make sure it's received it, and stored it to it's own global variable.
the second program connects to the dll successfully, but when it tries to retrieve the data, it returns 0's (NULL's)
My research:from what I've read, so long the dll is connected to a program, all additional programs will attach to the same instance.
how do I make the global variable in the dll be accessible to both programs? (without resorting to saving it to the HDD Idealy)
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Nov 4, 2014
I've changed up my code to the retail checkout WFA I am trying to make. I have an item list filled with objects of the now globally accessible 'Item' class, but I'm having trouble.
Essentially, I want to send an object of the item class chosen from a dropdown menu to form2, where I will fill in certain blank attributes with data entered in form2's text boxes and comboboxes. The problem, it seems, is I need another itemlist in form2 that will hold the object being passed to form 2, so I can then pass all the information to textboxes on form3 (the receipt/review page). It's been more than a year since I coded with C#, and I've forgotten quite a bit. I was also not able to find any tutorials on building an item list without an associated combobox or droplist, which is what I need.
This is my item class (minus most of its properties so the page doesn't stretch).
class Item {
public string prodName;
public string fName;
public string lName;
public string ccNum;
public string ccProv;
public string shipAddr;
[code] ....
For anyone who didn't see my last question, I'm in a User Interface Design class, not a C# class. I know this probably isn't the best code out there, but for my purposes the program just needs to compile beginning to end and pass the data like it should.
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Sep 28, 2013
There are 3 students (0=John, 1=Peter, 2=William) sharing their meals. Who does the cooking, does the shopping and pays for the bills. End of the month they sum it all up and settle the bills equally. Who must pay the most is outputted at the top, while the person that collects most is at the bottom. Students that have to pay the same amount are listed in the same order as they are ordered in the input. (receiving same amount, the same). Total of the settlement are rounded to whole cents. Sometimes they loose a cent, sometimes they gain one.
So I started making a plan what the program is supposed to do. Pen and paper:
1. Sum of the total amount from all the meals.
JohnPaid+PeterPaid+WilliamPaid=Total
Total / 3 = FairShare
calculate difference of all three the students
if JohnPaid == FairShare
print John receives 0.00
if JohnPaid > FairShare
print John receives difference
if JohnPaid < FairShare
print John pays difference
etc. (same for Peter and William)
Code:
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
/* type definition of student */
typedef struct student {
int who; /* 0=John, 1=Peter, 2=William */
float paid; /* amount that student paid */
[Code] .....
Example in/outputs:
<0 39.85>
<1 30.83>
<2 35.43>
Peter pays 4.54
William receives 0.06
John receives 4.48
<1 106.32>
<0 88.14>
<2 88.14>
John pays 6.06
William pays 6.06
Peter receivers 12.12
Looking at this code, I see a lot of global (general) variables. Do I need to adjust this skeleton code I received or should I just add code?
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Feb 15, 2013
I'm trying to compare two data files character by character to see if they are the same. If the files are different, the program should print out the line numbers of where they do not match. So far, I have the part where it returns 'T' for when the files are the same and 'F' when they are not. But how should I start where the program prints out the line number where the characters are different? I am thinking of an array but nor sure how to start it.
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Feb 25, 2013
I was wondering if i had to say simply retrieve data from a server whether it be simple plain text for variables or download whole files (FTP), what would be the best method for this? I would imagine there is a pretty big difference between retrieving text and downloading files but im just wondering what the best thing would be to research for both.
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Apr 5, 2013
I try to write my data into two different files and i just use something like this
ofstream myfile;
myfile.open("phase 1.txt");
if (myfile.is_open()) {
for(i=0;i<M; i++) {
[Code] .....
But it only generate the first file. How should i modify this?
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May 7, 2013
I am new to c++ programming i just want to know how to write the data into different files.Suppose my input files has 1-8 ids so each id data must be stored into each different file. And below is my code.
#include<fstream>
#include<iostream>
#include <cstdlib>
#include <algorithm>
#include<list>
#include <math.h>
#include<conio.h>
#include<string>
#define PI 3.14159265
using namespace std;
double angle;
ifstream indata;
ofstream outfile;
[Code] .....
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Apr 5, 2014
I am trying to use myfile to create and write user data to a file [URL].
At the moment I only want to save as .txt so that I can open it to see that it wrote to file properly.
The main issue I get is that it says the file is not open when my program gets to the error checking at the very end, a few guides mentioned that if the file was not yet created a file with the specified name would be generated in the same folder as main on the hard drive. I did try creating the file as a notepad .txt file but it still read the error. Here is the snippet concerning the writing of the file:
void WriteToFile() {
if(myfile.is_open()) {
myfile.open("userdata.txt",ios::in);
myfile<<"User name: "<<NameFirst<<" "<<NameLast<<"
[Code] ....
it compiles fine with the rest of the program and everything runs smoothly, it just isn't writing to a file.I have included <string>, <iostream> and <fstream>.
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Dec 17, 2013
I have the following code and I am trying to do simple math calculations to the data. I need to take the car price (y) minus down payment (z) and then divide that quantity by 12 times "yearsx" That answer is then assigned to x. The problem is that x will not print the correctly!I also noticed that if I increase the "count" to amnything higher than the number on lines in the file, I get the correct value for x but only on the last set of the struct..my file reads as follows:
last_name first_name car_price down_payment years
johnson bill 10,000 2,000 3
When I printf the struct to the screen, i need to do the following:
x = (10,000 - 2,000)/(12*years);
but this is the math part that wont work. I have checked and doubled checked number types and I cant get it right.
Code:
#include<stdio.h>
#include<stdlib.h>
#define FILENAME "file.txt"
#define SIZE 100
}
[code]....
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Feb 20, 2013
I need to convert characters in a input file to numbers in output file and display both the characters and numbers in a console window.Only 7 numbers can be displayed, the rest needs to be dropped.The input file contains the following data, with one number per line:
CALL HOME
GET LOAN
Hi THERE
BYE FOR NOW
For example, once the first number in the input file has been processed, the console window should display the following: CALL HOME 225 5466.
The output file should now also contain the number:
225 5466
Currently my console is displaying the following:
Enter the input file name.
infile.txt
Enter the output file name.
outfile.txt
2554663Invalid Input
4385626Invalid Input
4Invalid Input
84373Invalid Input
293367669Invalid Input
4357637277CALL HOME
GET LOAN
Hi THERE
BYE FOR NOW
#include <iostream> // for screen/keyboard i/o
#include <fstream> // for file
#include <cstdlib> // for exit
using namespace std;
void openFile(ifstream& infile)
[code]....
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Jan 27, 2014
I have a data buffer project in Windows 7 x64 embedded OS (using Visual Studio 2008), that would work simply like that:
One writer application will send data (no network protocols, just procedure call on the same machine) to my app like 20 packages per second, each data packages will be approximately 3 MB size and comes with a timestamp tag.
My application will store each data item for 100 minutes and then remove. (So I can calculate the total size from beginnig no need for dynamic allocation etc...)
Meanwhile there will be up to 5 reader applications which will query data from my app via Timestamp tag and retreive data (no updates or deletitions on data by reader apps).
So since the data in my buffer app can grow over 50GB I don't think that shared memory is going to work for my case.
I'm thinking about using Boost Memory Mapped Files or Windows API Memory Mapped Files.
So theoratically I will crate a fixed size File on harddisk (lets say 50GB) and then map some portion to RAM write the data to this portion, if the reader applications wants to use the data which is mapped currently on memory, then they will use directly, otherwise they will map some other potion of the file to their address spaces and use from there...
My problem is I haven't use Map File concept at all and I'm not a C++ developer so I'm not very familiar with the language fundementals. I've searched tutorials of boost and msdn for windows as well but there is not too much code example.
So I don't know how to map some portion of the data to memory and manage it, also how to search data in file or memory according to the timestamp tag. Yes there are codes for creating files and mapping the whole file to memory but none for dividing it into regions, aligning or padding the data which I need for my case.
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Nov 28, 2013
I'm trying to read stream data from a stream in a pdf file compressed in LZW. My first step is to read this compressed data into a buffer. The second step is to decompress it. I know how to decompress it, it is the first step I am having trouble with.
How should I read this data? If I read each character into a char the numerical output will not exceed 256. LZW compressed output should exceed 256.
I read the pdf in binary mode and have tried the read function like below.
From what I understand (don't quote me), I should be reading in 12 bits at a time. Is that correct and if so should I be using a bitfield. If I do need a bitfield then how to I read the data from the stream into a bitfield of 12 bits without restricting the binary value of the characters being read from the compressed stream.
Code:
ifstream inputfilestream;
inputfilestream.open("myfile.pdf", ios::out | ios::binary);
char mychar; //unsigned char gives an error though it can be //converted to unsigned char later.
while (inputfilestream.read(mychar, 1)) {
// do something with the char.. I have stored it in an int vector
}
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Dec 20, 2013
I am having a slight issue with the strcmp function. I am comparing string data from two different files. I want the function to output a set of information if the strings are the same and a different set of data if the strings are different. My issue is, the function outputs the data that's the same but not different.
I had an else statement that compared the data if it was NOT equal but it only duplicated the data in the file.
One file is a listing of 100 books with 10 lines of information and an assigned market. The second file is a listing of the markets contained in the books file. However, the books file has a market that is not located in the markets file. The "missing" market is what is not priting or displaying.
// final project2 file
#include <iostream>
#include <string>
#include <iomanip>
#include <fstream>
using namespace std;
const int ARRAY_SIZE = 500;
const int MARKET_ARRAY = 6;
ifstream infile, infile2;
ofstream outfile;
[Code] .....
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Apr 2, 2014
Whenever I run my program, It should be taking this string of information:
Shampoo 10 8.75 87.50
Pen 3 2.50 7.50
Headphones 5 20.99 104.95
MacAir 1 879.23 879.23
Raspberries 6 4.99 29.94
Oranges 5 2.79 13.95
Apples 3 3.85 11.55
From one file and outputting it to another, the finished product should look like:
Shampoo 10 8.75 87.50
Pen 3 2.50 7.50
Headphones 5 20.99 104.95
MacAir 1 879.23 879.23
cheapest item = Pen
most expensive item = MacAir
total cost = 1079.18
shopper = Mary Kay
Raspberries 6 4.99 29.94
Oranges 5 2.79 13.95
Apples 3 3.85 11.55
cheapest item = Oranges
most expensive item = Raspberries
total cost = 55.44
shopper = Winnie B. The Pooh
When I run my code however, it doesn't get past shampoo and will continue to add shampoo to the total cost infinitely. How can I change the code to produce the proper information?
CODE:
#include <iostream>
#include <fstream>
#include <iomanip>
#include <float.h>
#include <sstream>
#include <string>
using namespace std;
ifstream input_file;
ofstream output_file;
[Code] ....
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Apr 14, 2012
In my program I open two files and write data into each, and close them. this is done in a while loop.
int main() {
while() {
myFile = fopen("file1.txt","w");
myFile2 = fopen("file2.txt","w");
// write data into files using fprintf() in a for loop
fclose(myFile);
fclose(myFile2);
}
}
However, after some iterations the fopen() for myFile2 fails.
Debug assertion failed!
Program....
File ......srcfprintf.c
Line 55
Expression (str != NULL)
I have not been ableto locate the bug in the code that is causing the failure.
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Mar 10, 2015
I have a form with 2 text boxes (Email and Password)
The user fills in the text boxes and clicks on the Log in button. The code behind the log in button does the following, First connects to a table (Users) in phpmyadmin. Next runs a SQL query (SELECT * FROM `users` WHERE Email = '" + sEmail + "' AND Password = '" + sPassword + "'") sEmail being the variable created from the text entered in Email text box and the same for password.
Next if the record count == to 1 it opens up the main menu form and if the record count == 0 it fails and the user does not get to the main menu.
All of the above is fine and working however what I want to do is take over a variable from the log in form to the other forms.
The code is below for the sign in button as all my code is behind that (I think this may be where I'm going wrong).
public partial class WelcomeForm : Form{
public static string connStr = "server = localhost; " +
"database = ppw5; " +
"uid = James; " +
"pwd = buster;";
[Code] .....
And the Main menu form where I'd like to take a variable over with me, lets assume the variable is the UserID from the database table that I pull from the dTable I created.
public partial class MenuForm : Form {
//Call the CloseProgram class and create a new method called ClassClose.
CloseProgram ClassClose = new CloseProgram();
WelcomeForm User = new WelcomeForm();
public MenuForm() {
InitializeComponent();
[Code] .....
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Mar 28, 2014
I have two date/time structures which I'm populating, but when I populate the second one it sets the same values in the first. This is what I've got so far
tm *FirstDate = gmtime(&now);
tm *SecondDate = gmtime(&now);
cout <<"Enter your first date in the format dd/mm/yyyy" << endl <<">";
getline (cin,tempstring);
[Code] .....
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Jan 16, 2014
I am writing a piece of code that requires me to display the last 1000 lines from a multiple text files (log files). FYI, I am running on Linux and using g++.
I have a log file from which - if it contains more than 1000 lines, I need to display the last 1000 lines. However, the log file could get rotated. So, in case where the current log file contains less than 1000 lines, I have to go to older log file and display the remaining. For e.g., if log got rotated and new log file contains 20 lines, I have to display the 980 lines from old log file + 20 from current log files.
What is the best way to do this? Even an outline algorithm will work.
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Sep 16, 2013
When including a header file in stdafx.h, should that file still be included in the source file where it is actually used?
If it is included in both places, is the one in the source file ignored?
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Dec 6, 2013
I need to find inverse of a matrix data in binary file should be used to form matrix.its not finding inverse correctly rest is working good.
Code:
#include <stdio.h>
void createbin();
void display();
void inverse();
int main()
{
createbin();
display();
inverse();
[Code] ....
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Dec 26, 2013
I am writing a program where I need to read a byte of char data and convert it into a text string of binary data that represents the hex value...
i.e. The char byte is 0x42 so I need a string that has 01000010 in it. I've written the following subroutine....
------------- My Subroutine ----------------------------------------------------------------------
void charbytetostring(char input, char *output){
int i, remainder;
char BASE=0x2;
int DIGITS=8;
char digitsArray[3] = "01";
[Code] ....
When I submitted the byte 0x42 to the subroutine, the subroutine returned to the output variable 01000010... Life is good.
The next byte that came in was 0x91. When I submit this to the subroutine I get garbage out.
I am using a debugger and stepped through the subroutine a line at a time. When I feed it 0x42 I get what I expect for all variables at all points in the execution.
When I submit 0x91 When the line remainder = input % BASE; gets executed the remainder variable gets set to 0xFFFF (I expected 1). Also, when the next line gets executed..
input = input / BASE; I get C9 where I expected to get 48.
My question is, are there data limits on what can be used with the mod (%) operator? Or am I doing something more fundamentally incorrect?
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