C++ :: reading Stream Value From A File?
Oct 13, 2013
#include<fstream.h>
#include<conio.h>
#include<string>
class CLS {
public : string name;
[code]....
I have used the above code to write the class instanc to a file "Text.txt"...But it seems that "f.write((char*)&c, sizeof(CLS));" is not working properly with string. The data can easily be written using stream object!
#include<fstream.h>
#include<conio.h>
#include<string>
class CLS {
public : string name;
[code]....
When I tried to read the data on the file...., it gave an error "Thread stopped...violation.."
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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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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 4, 2013
Why does my loop loops 3 times when i have only 2 line of data in my file? From the cout << s.size , when i run it will show 1,2,3.
Information in txt file
Code:
local john 10/2/1990
international tom 2/5/2000 output Code: local john 10/2/1990
international tom 2/5/2000
international tom 2/5/2000 Code: ifstream in(filename);
[Code] ....
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Mar 4, 2013
I'm having some trouble with copying one I/O stream into another. I've put the first one into an array but I cannot get my second prompt to copy the .txt file the first prompt sees and outputs to the console. When I try and grab the info from the .txt file my first prompt sees I only see blank space in my .txt file.
#include <iostream>
using std::cout;
using std::cin;
using std::endl;
#include <fstream>
using std::ifstream;
using std::ofstream;
[Code] .....
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Apr 7, 2014
I am currently trying to read in a file that takes in the input in the following form.
Code:
HANK>25 BOB>31 AL>54
BILL>41 ABE>63 JEFF>50
I have tried the following solution:
Code:
#include<ifstream>
#include<iostream>
using namespace std;
struct node
{
string name;
int age;
);
int main ()
{
[code]....
The problem is a.name, it's extracting the entire string before the space character causing p.age to contain "BOB" and so on. I've tried using p.get(p.name, sizeof(p.name), '-') with '-' as the delimiter and p.getline() using a character array instead of a string. How would it be possible to only copy the string into a.name before the '>' character?
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Sep 20, 2013
Let us assume I have a program that takes the name of the output file from the command line. Now let us assume that a decided not to give any output file location but wanted my program to to print my strings/ints ... directly to stdout. how would one do this using file streams? Using file pointers and c that is pretty straight forward but how would i achieve this in c++.
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May 9, 2014
#include <cstdlib>
#include <stdio.h>
#include <string>
[Code]....
I'm trying to load a file input stream to load all the character content into a variable (say from a .java file for example), but for some reason whenever I type in the name of the file I want to stream I get the report: RUN FAILED (exit value 1, total time 2s)
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Apr 26, 2012
I have function which will replace (or create) an file with the contents of another stream. The stream could be anything. The replacement is done safely.
Code:
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <unistd.h>
int do_replace(const char *file, int stream, int cnt) {
[Code] .....
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Nov 10, 2014
I am trying to do some exercises but am struggling at the moment. The first task was to create a class (Planet), then allow the user to edit their entry or view it.
The second one is to create class instances from a text file. The file contains a new planet on each line in the form: 'id x y z' where x/y/z are its coordinates. As the file can have more then one lines, it has to dynamically create an undefined amount of class instances.
To do this I used 'new' and it works ok - it prints each one out to the screen as you go so you can see it working. However... I'm trying to get into good habits here and am encapsulating the class which is where I am getting stuck. I can read from the class but cannot put the values from the file into the class.. ..using the member functions I have created anyway.
My code so far is:
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
class Planet {
private:
int id=0;
float x_coord=0.0, y_coord=0.0, z_coord=0.0;
public:
int GetID(){return id;}
[code]....
If I change the SetID etc to just p->id, p->x_coord etc it works fine. But I'd rather find a way to do it that keeps the encapsulation. Using p->z_coord etc requires that you change the class variables from private to public.
The question I have been given is this:
Define and implement a function, generate planet, that takes a stream argument that has already been connected to a file (i.e. the argument is istream& fin). The function must create a new instance of planet using new and read its details from the next line in the file.Each line of the file is in the format id x y z.The function must return the newly created planet.
Also, how would you go about 'viewing' one specific class instance once they've been created? So say the file had 5 lines, line three was '4 6 2 6'. How would I go about viewing that planet afterwards? I don't think thats required but... I'm just wondering Although I'm also wondering, are we actually creating a new class instance for each line here? Or just destroying the previous one?
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Jun 23, 2013
What is the traditional way to monitor a blocking subroutine that is using a file stream as its input? That is, what is the traditional way to make a progress meter in the console?
Say I have a function that takes in a filestream and works with it. Suppose this file stream has a position and length property like in C# FileStream:
Code:
void sub (filestream file)
{
//read a bit of the stream, which advances stream cursor position
//do something
//repeat until all of file stream has been used up
}
Presumably the function is chomping along the file stream as it is doing some calculations serially on the file stream.Because the function is blocking, there is no way to access the file streams position and length in this thread. So naturally it seems like the best thing to do to monitor the progress of that function is to make another thread and pass it the file stream object as a parameter, and in this separate thread, monitor the distance between filestream's position and length to determine how much of the file stream has been used up, and every second or so output the amount of file stream used onto the console.
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Feb 12, 2014
So I'm trying to count the number of lines in a text file that is inputted by the user. Also the code doesn't sum up the last number of the text file (exmp it calculates and print only 14 from 15 numbers). I'm a beginner in c++ programing.
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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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May 9, 2014
Debug Error
ProjectsFinal ProjectGrItemDebugGrItem.exe
R6010 - abort() has been called
I was going over this with a friend and it seems as though getline() is not reading anything in and thus throwing the abort error. I'm not sure why this is because I've included the textfile, with the correct name of course, in both the regular file location and the debug folder. I ask for user input and the user then inputs the name of the file they want, I do some required things behind the scenes and display the results for them in a cmd window. I've included pastebin files for both my header and cpp files because it is far to large for one post I shall, however, post the full code in the comments.
Quick Code
The problem occurs on line 159. I'm assuming once this line is fixed, line 163 will have the same problem.
// Read regular price
getline(nameFile, input, '$');
vectorList[count].regPrice = stof(input.c_str());// Casts string to a float
// Read sale price
getline(nameFile, input, '#');
vectorList[count].salePrice = stof(input.c_str());
Pastebin Links : [URL] ....
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Mar 27, 2013
Write a program which reads a stream of numbers from a file, and writes only the positive numbers to a second file. The user should be prompted to enter the names of both the input file and output file in main(), and then main() will open both files. Another function named process() must then be called to read all the numbers from the input file and write the positive numbers to the output file. Note that you must pass the open stream variables for each file as arguments to the process() function, and that you need to (always) double check that the files opened successfully before using them.
This is what I have so far but its not working out!
#include <iostream>
#include <fstream>
#include <stdlib.h>
using namespace std;
int process(ifstream &inf, ofstream &outf);
[Code] ....
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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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Nov 26, 2013
Program background: Ticket Sales Details You will sell tickets in advance and at the door. Prices for buying in advance and at the door will be given. Also, the total number of tickets sold in advance will be given. Each guest will have a unique number. If there are n tickets sold in advance, then these guests will be numbered 0 through n-1. As the event starts, requests to buy tickets at the door may be made and these guests will be numbered sequentially, starting at the lowest unassigned number. The maximum number of guests will be 1000. The first line of the file contains the following three values, separated by spaces: Cost of the presales tickets (in dollars), Cost of the tickets at the door (in dollars), and the number of presale tickets. The first two values will be positive real numbers to two decimal places and the last will be a positive integer.
The second line of the file will contain one positive integer representing the number of auction items followed by a positive real value to two decimal places (at most) representing the minimum bid increment, in dollars. The first value is guaranteed to be 1000 or less and the second will be in between 1 and 50, inclusive.
The third line of the file will contain all the prices of the auction items, in dollars, separated by spaces, in order. Thus, the first price is the price of item 0, the next price is the price of item 1, and so on. These values will be real numbers represented to up to 2 decimal places.
The fourth line of the file will contain the three following positive integers pertaining to the raffle: the number of raffle tickets available, the cost of a raffle ticket in dollars, and the number of raffle prizes. (It's strange to have raffle tickets that don't cost a whole number of dollars.)
The fifth line of the file will contain each of the values of the raffle items, in dollars, separated by spaces, in order. Thus, the first price is the price if item 0, the next price is the price of item 1, and so on. These values will be real numbers with upto 2 decimal places.
The sixth line of the file will contain ten positive integers representing the number of each of the drinks 0 through 9, in order, that are in stock.
The seventh line of the file will contain ten positive real numbers with upto 2 decimal places representing the price of each of the drinks 0 through 9, in order.
The eighth line of the file will contain a single positive integer, numEvents, representing the number of events that occur at the charity ball. These events are split into two groups: actions by guests at the ball and awards given (raffle, auction, person, totalrevenue). All of the actions precede all of the awards. You will produce exactly one line of output for each event described. Here are the formats of each event that could occur:
If a patron buys a ticket at the door, a command will be on a line by itself:
BUY TICKET k
where k is a positive integer indicating the number of tickets bought at the door. These guests will be numbered as previously mentioned. You are guaranteed that the total number of tickets bought, including presales, will not exceed 1000. This is what I have so far and I cannot figure out why it wont calculate the total revenue. I am not completely sure if it is even accessing the if statement in main.
Code:
#include <stdio.h> #include <stdlib.h>
#include <string.h>
#define N 1000
[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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Jan 28, 2014
I am trying to write a program that will open a file with 2 points, take those points, determine what quadrant those points are in, and save the result back into the same file without truncating the data.
I'm having some trouble with my file I/O. I can't get my program to read the two values for X and Y that I put in the points.txt file. It simply uses whatever random number was used last time in that block of memory. In my points.txt file I put something like "4 -5" and it wont assign those numbers to my X and Y variables. I believe the issue is on line 25
#include <iostream>
#include <fstream>
using namespace std ;
int main() {
//defining X and Y
double X, Y ;
[Code] ....
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Jan 5, 2014
If I am reading data from a .txt file with a person's last name and first name (e.g. Miller Andrew), How do I output the same data with the first name followed by the last ?(e.g. Andrew Miller) Do I use the ignore function?
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Aug 30, 2014
I want to know how to read a .pgm file from my hdd and store it in a 2d array so i can perform some action on the array later on. This is ny first time working with an imqge in c so i know nothing about it. .
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May 25, 2014
I have been given a task to make a c++ program that promptsd the user to enter a mp3 file name, read the ID3v1.1 tag and displays it. It then should prompt the user to to decide if they want to edit the comments section of it, then if they edit the section, it should re-print the updated ID3 tag. The list of genres are in a cstring that is as follows.
char genre[126][128] =
{
"Blues" "Classic Rock", "Country", "Dance", "Disco", "Funk",
"Grunge", "Hip-Hop", "Jazz", "Metal", "New Age", "Oldies", "Other",
"Pop", "R&B", "Rap", "Raggae", "Rock", "Techno", "Industrial",
"Alternative", "Ska", "Death Metal", "Pranks", "Soundtrack",
[Code] .....
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Aug 22, 2012
Using the feof() function in the output file i have the last value twice.
This is the input:
1 3 6
1 1 4
0 3 1
1 1 6
0 6 2
1 1 6
And the output should be:
12
6
15
13
But using the feof() the last value appears twice:
12
6
15
13
13
How can i change that?
while(!feof(pfile1)) {
sum=0;
fscanf(pfile1,"%d%d%d",&choice,&day,&val);
if(choice==0)
[Code] ....
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Feb 24, 2013
I'm trying to display an image from a stream data. But there is no image when getting image::from stream.
It's my source code:
Code:
IStream* pstream = NULL;
if(SUCCEEDED(CreateStreamOnHGlobal(NULL, TRUE, &pstream))) {
ULONG lreal = 0;
pstream->Write(chIncomingDataBuffer, iEnd, &lreal );
[Code]...
There is no image from data.
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Feb 6, 2013
Do stream iterators, such as std::istreambuf_iterator<char>, read a chunk of bytes internally, or do they read the stream one byte at a time?
Because I am thinking to write a BufferedFile class which uses an std::vector<char>.
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Mar 10, 2014
I'd like to be able to output sound over skype as if it were coming from my headset, how would I go about this?
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