C++ :: Stream Data To A File And Then Return To File To Add Further Data?
Aug 23, 2012
I am trying to stream data to a file, and then return to the file to add further data. When I add data the second time, I then want to update the value of the second byte in the whole file. I can't seem to do this!
Here is my sample code:
Code:
int a = 1;
int b = 2;
int c = 3;
int d = 4;
int e = 5;
int f = 6;
int g = 7;
int x;
fstream out1("file.dat", ios::out | ios::binary | ios::trunc);
[code]....
The output I get is "1, 2, 3, 4, 5, 6", but I want to be getting "1, 7, 3, 4, 5, 6", because in "out2", I seekp to the second integar entry, and change it to "7".
I have also tried using ios::ate in the constructor for "out2", but this gives me the out put "4, 7, 6, 6, 6, 6", which is suggesting that when I create my fstream object "in", any seekg commands are relative to the beginning of the "out2" stream, rather than the "out1" stream.
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Jan 21, 2014
I have two puzzling issues I am dealing with.
Issue 1: I am using a stringstream object in a block of my program that needs to be visited repeatedly depending on a user's selection from a menu. I want the contents of this stringstream object to be cleared any time control gets to this part of the program. I have tried the clear and flush functions to no avail.
Issue 2: I am reading data from a source text file that would be regularly changed during the course of program run. After the program run is over, I am supposed to save the results(which is basically the source text file AND all updates) in a destination file. This destination file would then serve as the source file when next the program is run. In other words, I want a scenario where my results overwrite the original contents of the source file; implying that my source and destination files are now one, pretty much. How can I do this?
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Oct 28, 2014
I am trying to write my files to another subfolder . Below is my program.
Code:
cat th6.c
#include <pthread.h>
#include <stdio.h>
#include <string.h>
#define SIZE 8
#define NUMELM 8
[Code] ....
I observe my filename along with directory as text in the new file created in sublfolder. This is output.
[cporgs/apue/threads]: mkdir first
[cporgs/apue/threads]: ./a.out test.txt first
test.txt -- first/test.txt
dfdfdfdfdfdfdf-14
dfdfdfdfdfdfdf-14
in thread test.txt first
[cporgs/apue/threads]: cat first/test.txt
dfdfdfdfdfdfdffirst/test.txt
[cporgs/apue/threads]: cat test.txt
dfdfdfdfdfdfdf
I could not able to get from where this filename and folder is getting added.
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Apr 11, 2015
I am trying to read data from more than one file at once. The files are different types e.g. one is a text file one is an xml file like so, StudentInformation.txt, CollegeInformation.xml. The files are all stored in one place, in this case on the D drive of a local computer. I am trying to locate any files in the D drive with a file extension of .txt or of .xml (there may be more than two of these files in the future, so I'm trying to allow for that). Then I want to open all of these files, extract the information and output all the information in one display window. I want all the information from these two or more files to be displayed together in the display window.
Here is the code so far. It is throwing up errors.
//Load from txt files
private void btnLoad_Click(object sender, RoutedEventArgs e)
{
IEnumerable<string> fileContents = Directory.EnumerateFiles("D:\", "*.*", SearchOption.TopDirectoryOnly)
.Select(x => new FileInfo(x))
.Where(x => x.Extension == ".xml" || x.Extension == ".txt")
.Select(file => ParseFile(file));}
[Code] ....
The error it throws up is:
Error 1 'BookList.Mainwindow.ParseFile(System.IO.FileInfo)': not all code paths return a value
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Nov 12, 2014
I have been asked to create a program that accesses an inventory file done in excel, look for a alpha-numeric code, which will be inputed by the user, and return to the user informations related to the position of that code, and informations related to the header of the column in which the code resides.
An example of the function I need the program to perform would be:
User inputs: 1429-R1
And the program returns: Marco's 6A, 8/21/2014, 3/7/2014.
using the following example of file:
Marco's 6A
Assessment 8/21/14 3/7/14
1584-R1 1584-R1 1584-R1
1461-2R1 1461-2R1 1461-2R1
1429-R1 1429-R1 1429-R1
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Mar 8, 2013
Ben has been administering a MBTI personality test. Now he has all the responses, but the task of scoring and compiling results seems daunting. The personality test* is a series of 70 questions for which the available responses are ‘A’ and ‘B’. Based upon the answers to the 70 questions, a personality profile is determined, categorizing the degree to which the responses place the person on four scales:
Extrovert vs. Introvert (E/I)
Sensation vs. iNtuition (S/N)
Thinking vs. Feeling (T/F)
Judging vs. Perceiving (J/P).
Each of the 70 questions relates to one of the four scales, with an ‘A’ response indicating the first of the corresponding pair (E, S, T, or J) and a ‘B’ indicating the second (I, N, F, or P). For instance, an ‘A’ response on the question: At a party do you:
A. Interact with many, including strangers
B. Interact with a few, known to you indicates an Extrovert rather than an Introvert; just the opposite for a ‘B’.
For this test, each question is designed to influence one of the four scales as follows:
questions 1, 8, 15, 22, 29 … are used to determine E/I,
questions 2, 9, 16, 23, 30 … and 3, 10, 17, 24, 31 … to determine S/N,
questions 4, 11, 18, 25, 32 … and 5, 12, 19, 26, 33 … to determine T/F, and
questions 6, 13, 20, 27, 34 … and 7, 14, 21, 28, 35 … to determine J/P.
Notice these come in sequences of “every 7th” question.
The goal of the test is to determine which end of each of the four scales a person leans, and to thus classify him/her based on those leanings (e.g., as ENFJ, INTJ, etc.). Since Ben would also like an indication of how strongly the test taker fell into each of the four, the program should print the percentage of ‘A’ responses for that scale.
Input for this program should come from a file responses.txt. The first line of the file will contain a single integer, n, indicating the number of test results to follow. Each of the following n lines will contain the first name of the test taker, a single blank, his/her last name, a single blank, then the 70 responses he/she gave on the test. Although the test instructions indicate that the results are most valid when all questions are answered, sometimes respondents leave questions blank. In that case, a dash appears at the corresponding place in the list of responses.
Output for the program should be written to the file types.txt. It should include a well-formatted report listing, for each test taker, his/her name, the percentage of ‘A’ responses in each scale, and the resulting personality type. A tie within a scale should result in a dash (‘-‘) for that part of the personality type.
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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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Apr 19, 2013
I want to input data into text file while not deleting the original data in the file and I use something as
ofstream writefile;
writefile.open("example1.txt");
if (writefile.is_open()) {
for(j=0; j<N; j++) {
[Code] ....
But this will delete the original data.
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Mar 28, 2015
#include <iostream>
#include <fstream>
using namespace std;
int main() {
int r = 0;
int c = 0;
int num[17][15] = { 0 };
[Code] ...
// Here is my code for displaying the data from the text file into a 2d array and height next to it, but I am not able to diaplay the height from 60 to 76 next to the row of the 2d array, as shown in the table below. This is my program:
Recently the health authorities have listed a new way to calculate the body mass index (BMI) of an individual.
Values of 20 – 24 are classified as normal, 25-29 as overweight, and 30-34 as heavy.
The table below is a portion of a typical BMI table.
BMI:202122232425262728293031323334
Height:
60102108113118123128133138143149154159164169174
61106111116122127132138143148153159164169175180
.
.
.
MY task is to write a program that does the following things:
1.Produce the table by reading in the data from bmi.txt (on Moodle) into a 2-D array.
2. Display the table neatly on the screen, with row and column headings. The BMI should go from 20 to 34. The height should go from 60 to 76 inches.
3. Prompt the use for their height (in inches) and their weight.
4. Make the program print the closest BMI.
If their weight is lower than the values on the table, use 20 as the BMI.
If their weight is higher than the values on the table, use 34 as the BMI.
5.Loop the program so the user can find more BMI’s.
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Jan 11, 2014
I'm reading from a file the middle column of data (Volts) where my test file "AP.txt" is opened by my program. Here is a segment of the data:
time Volts dV
49552 -66.20183 -0.01556807
49553 -67.76025 -0.01556495
49554 -69.30704 -0.01533247
49555 -70.81799 -0.0148486
49556 -72.26774 -0.0141133
49557 -73.63226 -0.01315276
49558 -74.89141 -0.01201764
Since the calculation I performed gives me -71.77 Volts, I need to match this value to the time that this occurs closest to using my program, and output the time that this occurs at.
Here is my program so far:
int main()
{
std::ifstream inFile;
inFile.open("AP.txt");
ofstream results_file ("maxvaluewithinput.txt");
float TimeAtdVMax = 0;
float VoltsAtdVmax = 0;
[Code]...
If you're curious, this program isn't for homework. It's part of the independent learning on C++ I'm doing for a Master's Thesis; the program will eventually model the APD90 of a ventricular action potential.
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Jan 30, 2013
I am very very new to C++. A bit of background. I have been writing in excel vba for large number crunching, and the code is now taking quite a while to run. A friend of mine suggested i start writing in C++, so i read up on it. And downloaded Code:Blocks.
My VBA Code is:
Sub arrayss()
Dim NameArray As Variant
Dim datarray As Byte
Dim DirectionArray As Variant
Dim WinArr As Variant
[Code] .....
Ultimately i would like to recode this to C++, but my first and probably silly question is how do i get the data from Excel to use in C++. I was thinking either to put the data in 3 csv files and convert into three Arrays in C++. Or maybe create a library of the data in C++. Ultimately it is speed i am looking for, so before i start recoding i wanted to start with the best way.
The data is like this in excel: (don't know how to create a table)
ABC DCA GFE THE
15 0 1 0 1
30 1 0 1 0
45 1 1 0
00 0 0 1
15 1 1 0
15 1 0 0 1
15 0 1 1 1
30 1 0 0
45 1 1 1
So the headers would be in one array, the 15's, 30's etc would be in another array and the 1's and 0's and Empty ( i need it to record an empty cell) would be in another array...
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Apr 29, 2013
I wrote a program to write text contents to file stream through fputs, the file stream address was changed in the middle of writing text content to the stream (11% text content have been put into the file stream), that cause the file stream pointer can be evaluated problem and raise exception on stream validation code in fputs library function, my question is what things could go wrong to make file stream pointer changed its address to something else or a NULL pointer if the file stream have not been flushed and closed.
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Jan 8, 2014
Code:
#include <fstream>
#include <string>
using namespace std;
ifstream inf("file name");
string line;
while (inf.good()) {
getline(inf, line);
}
instead of line by line i want the complete data from file to the string.What modification i have to do?
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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 19, 2012
I need make a CBitmap or a streamdata from a System.Windows.Controls::Image(rendered out put)in a SDI mfc application (supporting clr). Here is my codes:
Code:
using namespace System;
using namespace System::IO;
using namespace System::Collections::Generic;
using namespace System::Windows;
using namespace System::Windows::Controls;
[Code] .....
By this codes i can read datastream from bitmapSource but in this way somthing goes wrong in most of GIF animations. After debug i found out i need 3 more things too decode a gif animation - (x,y) position and size of each frame and disposal method for each one - finally i just found a way to draw tru images on a form window by this codes:
Code:
System::Windows::Window^ mainWindow;
mainWindow = gcnew System::Windows::Window();
mainWindow->Title = "GIF Imaging Sample";
//ScrollViewer^ mySV = gcnew ScrollViewer();
array<System::Byte>^ pixels = gcnew array<System::Byte>(bitmapSource->PixelHeight * Stride);
[Code] ...
When i change
Code: bitmapSource = decoder->Frames[0];
to
Code: bitmapSource = decoder->Frames[01];
frame[1] has drawn perfectly on window(i think some how Image class takes care about - (x,y) position and size of each frame and disposal method for each one ),so im wonder if how can i make a CBitmap or a data stream from System.Windows.Controls::Image class to use in mfc app.
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Jun 4, 2013
I have written a C++ program I have multiple of CSV file used as input, which I open one at a time and close it after extracting data to a output file which is the only file.
I run getline(inFile,line);
outFile << line << endl;
I run this code, and only part of it is goes to the output file I got, also have spacing randomly to specific file and inconsistent
But when I slower the code, like system("Pause") in the loop, I can get extract what I want perfectly....
Is my program running to fast, why getline would be skipping part of what things I want?
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Nov 24, 2013
I have this code for a computer project... (store management) but the character strings are not copied on text file..
#include<iostream.h>
#include<conio.h>
#include<fstream.h>
class Store {
public:
char *item_name[5];
store()
[Code] .....
Now when i run the program, it gives a error :::
ERROR
address 0x0
How can i write these strings to the text file?
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Mar 8, 2013
Code:
#include <stdio.h>
#include <stdlib.h>
int main (int argc, char *argv[])
{
char buffer[256];
FILE * myfile;
myfile = fopen("read.txt","r");
[Code]...
I also got an error in printing wherein the data in read.txt is "Hello" newline "World" and my program prints world twice.
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Mar 27, 2014
I have a program I have to do that counts the number of words in a text file. I have tried the code on 2 computers now since my programming teacher told me the code was fine. Here is my code:
#include <iostream>
#include <string>
#include <fstream>
using namespace std;
int main() {
ifstream infile;
infile.open("tj.text" , ios::in);
[Code] .....
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Nov 7, 2014
I am reading a file then printing the data onto the other file. It is working, however when I check to see if each variable is being properly set after reading the file a issue arises.
Example of the file being read
Code:
Vehicle PV50CAN passed camera 1 at 05:33:26.
Vehicle W867BRO passed camera 1 at 05:33:29.
Vehicle KQ63ARU passed camera 1 at 05:33:38.
Vehicle K954ITQ passed camera 1 at 05:33:40.
Vehicle V220MXB passed camera 1 at 05:33:42.
[Code] .....
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Nov 8, 2014
I need to perform operations on data from .data file i am able to load the file but how to use the data and perform operations on it. The file had roughly around 200 entries.
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Dec 6, 2013
Following is the program I wrote it basically takes 9 inputs and then save them into binary file. then print out the data stored in binary data and find inverse of it then print the inverse out. but its stuck in a loop somewhere.
Code:
#include <stdio.h>
int main() {
int a[3][3],i,j;
float determinant=0;
int x;
FILE *fp = fopen ("file.bin", "wb");
[Code] .....
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Aug 16, 2014
How to use fgets(). I cant understand the bookish definition. I want to get some data in a file.
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Aug 16, 2014
I'd like to get only the third column of this file into a c-programm and to calculate the mean value of that numbers.
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Aug 1, 2013
I've got two columns of data.
Code:
int a[6]={1,3,5,8,10,12};
int b[3]={3,5,9};
int c[6]={0}; if a is equal to ANY of the data in b, then c= a*2
if a isn't equal to any of the data in b, then c=a.
Here is the answer I want
Code:
c[6]={1,6,10,8,10,12}
I tried using two for loop, but it isn't correct.....
Code:
int a[6]={1,3,5,8,10,12};
int b[3]={3,5,9};
int c[6]={0};
for(int i=0;i<6;++i){
[Code] ....
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Apr 7, 2014
In my main I have a do/while loop, which is to iterate around the method calculateImportance while i is not equal to the numNodes.
do
{
int i;
int numNodes = Test.count();
for(i=0; i<=numNodes; i++)
[Code]....
I have been messing around with the data type node, hence why it is there are present, but, that doesn't seem to the answer
This is the function declaration in the header file.
node CalculateImportance();
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