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++.
View 12 RepliesI am a bit confused about dup2. I am trying to redirect stdout to file and back. It works with a fork(). I'm having trouble making it work without forking. Closing file descriptors has something to do with it...
int main() {
int pid;
int fd;
int defout = dup(1);
fd=open("out.txt", O_RDWR | O_TRUNC | O_CREAT);
dup2(fd, 1); // redirect output to the file
[Code] ....
So what does close have to do with anything?
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.
View 5 Replies View Relatedi am writing a c program, that sets up serial communication with my modem. The program works so far but i want the output to be redirected in a .txt or .csv file.
Code:
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>
[Code]....
I have this code:
Code:
#include <stdio.h> //printf
#include <stdlib.h> //exit
#include <unistd.h> //fork
#include <sys/types.h> //pid_t
#include <sys/wait.h> //waitpid
}
[code]....
I would like to, when running cat, send in some data like "testing" to its stdin, and then catch the output of stdout, and put it into a character array variable.Currently the parent stalls till the child is done.I imagine the parent has to some how detect that the child executed 'cat', and then send in input to stdin?Then somehow detect that 'cat' is done executing, and read the output from stdout? I have looked around and found "dup2", but I don't understand how to send in and get data to the child from the parent, especially since the "file descriptors" is not pointing to any files in the first place..
I want to build a proxy, middleman between various client programs on my machine and servers outside, like this:
Client -> Proxy -> Server, Client <- Proxy <- Server.
OSes are Windows XP, 7 and 8.
Within that proxy I want to analyze data before it reaches it's destination and have full control over it to the point where I can prevent a packet from reaching it's destination if my program finds something suspisious going on. I need incoming and outgoing traffic of specific adresses and ports to be forwarded into my application on my client machine. My app then should deliver packets to their destination after they were analyzed.
The parts where data is received, analyzed, manipulated if needed, and sent is something I could code with no difficulty. But the concept of redirecting and forwarding is hard for me to grasp at the moment. I'd like to know at least what winsock functions I have to use.
If it's possible, I would like to use Windows libraries only, nothing from 3rd parties.
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] ....
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] .....
#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?
#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)
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] .....
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?
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.
View 3 Replies View RelatedI 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?
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] ....
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] ....
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.
I've been working on a function that works like a pipeline of a shell but receives a directory, go over it an search for every file to send it to a filter, something like this in bash "cat dir/* | cmd_1 | cmd_2 | ... | cmd_N", The only problem i have with the code is the redirection of the pipe descriptors.
Code:
int main(int argc, char* argv[]){
char** cmd;
int Number_cmd;
cmd = &(argv[2]); /*list of cmds*/
Number_cmd = argc-2; /*number of cmds*/
}
[code]....
The code is seems to work fine except when i run it with more than one command in example ("./filter DIR wc rev") in this case it returns
wc: standard input: Bad file descriptor
wc: -: Bad file descriptor
0 0 0
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.
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>.
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?
View 1 Replies View RelatedI need to use getchar and putchar. The task is simple to say but not that easy to implement as it may seem. I end up with:
char c = 0, c_ = 0, c__ = 0;
while ((c = getchar()) != '.') {
if (c == 't') {
c__ = c;
c = getchar();
[Code] ....
If the word "the" is followed with another one, the last isn't eliminated. I enter "thethe" and get "the", what is not right.
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.
This is my code:
#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.