Visual C++ :: File Stream Change Its Address During Writing Text Contents To The Stream
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.
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) {
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?
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?
Try to implement overloading << operator. If I done it void then everything work fine (see comment out) if I make it class of ostream& then the operator return to me some memory address.
Code: #ifndef Point_HPP // anti multiply including gates #define Point_HPP #include <sstream> class Point { private:// declaration of private data members double x;// X coordinate double y;// Y coordinate
I'm trying to read in two instances of date and time (from user input) into a string value (MM/DD/YY hh:mm). I need to be able to calculate the difference between the two in order to return how much time has elapsed from the first date/time to the second date/time.
What would be the most efficient way to go about obtaining said results?
I was thinking I need to convert each year, month, day, hour, and minutes into its own integer variable, after researching immensely online I'm still not sure how to convert from a string of characters to an integer.
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: 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.
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);
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;
#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.."
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?
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++.
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)
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.
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.
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());
I have a character pointer that points to 4000 bytes of valid data. I need to write these valid contents pointed to by this pointer into the file. I am looking for the most optimized way of doing this. I am using the below logic which seems trivial. Any better approach to accomplish the same?
/* length is the number of valid bytes of data */ void parse_contents(const char *data, int length) { int j = 0; char path[1024] = "/tmp/data.xml"; FILE *fp = NULL; fp = fopen(path, "wb");
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);
I'm supposed to add two new functions to an existing class that I've written early on: readData(ifstream&)and writeData(ofstream&).
The parameters of the program are: -Create three employee objects as shown, -Create an ofstream object and open a file. Choose any name for the file that you want. Do not ask the user for the file name. Pass just the file name as the parameter (no path) so that your program assumes the file to be in the same folder as your executable file. -Send messages to each of the three Employee objects to write themselves out to the file. -Close the file. ...
If I get writeData(ofstream&) function bit to work! for brevity I've cut all the functions of the class that arent necessary. Here's what I have so far:
Employee.h #pragma once #include<string> using namespace std;
[Code] ....
So I've tried a bunch of different ways to get my objects into the ofstream object to write them to the file, but I'm supposed to use the two new functions somehow...but I'm way lost.
#include <iostream> #include <string> #include <istream> #include <sstream> using namespace std; int main() { string groups[3] = {};
[Code] ....
It outputs jibberish. I can do what I need to do but I would need to declare more variables and write more cout's, isn't there a way to add these elements to a stringstream or streambuffer? My goal is to write this program and make it as comprehensive as possible but also with very few lines.
