C :: Create 9 Child Processes And Eventually Write From Each Process To Another?
Nov 18, 2013
I want to create 9 child processes and eventually write from each process to another. How can I specifically create 9 child processes and leave them running? Right now, I am using a loop from i=0 to i=8 and running fork() within that loop, but each child process also runs the loop, which spawns dozens (maybe hundreds?) of processes. I specifically only want to create nine of them. How can I do this?
Code:
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/types.h>
[Code].....
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May 5, 2014
I wrote a C program that is supposed to create a certain number of child processes, each child process having to change 1 letter from a string. The string and the number of child processes are read from the keyboard. I want to do it using pipes.
It should work like this: The parent changes one letter, then the first child takes the string modified by the parent and changes one more letter. The second child takes the string modified by the first one (2 letters are already changed) and changes one more and so on. I am new to C and am not quite sure how it all works, especially pipes. Also can the children be linked between them through the pipe, or can they only be linked to the parent and it has to be something like: first child changes a letter, gives the string back to the parent and then the second child reads from there, modifies letter and gives back.
If it's like that, is there any way to make sure that this doesn't happen: Apples becomes AppleD and then AppleX and then AppleQ? For example:
Code:
Input: Apples
Output: Applex Appldx Aqpldx My problem is: I don't get any output from the children.
Here's my code:
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<sys/types.h>
#include<unistd.h>
#include <sys/wait.h>
[Code] .....
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Mar 19, 2014
I want parent and child processes to communicate in C linux using pipes. I have created two file descriptors. one for parent to child i.e. readpipe and other writepipe for viceversa. But I am getting null as output for ch and ch1 strings in my code below.
#include <stdio.h>
#include<stdlib.h>
#include
#include<unistd.h>
int main(){
pid_t pid;
[Code] .....
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Oct 11, 2012
how I can run this as a separate process from the parent program, like a child process,
and return the result back to the parent program.
this script is as follows.
if file "/Stuff/s" exists then continue to run, if file "/Stuff/t" exists, then print "started" if file "/Stuff/t" does not exists, then print "stopped"
if file "/Stuff/s" does not exist then print "quit" and then quit.
Code:
void controlxmmscheck( ) {
if( access( "/Stuff/s", F_OK ) != -1 ) {
xmmscheck
} else {
[Code]....
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Apr 15, 2012
I'm trying to build a basic shell for Unix. This is the code I use to create a new process:
Code:
pid = fork();
if (pid == 0) {
setpgrp();
complexCommand(argv, isComplex);
[code] .....
Where complexCommand is a function that handles the command (uses execvp after generating the correct string out of argv). My problem is that after if while in the shell I use a program that needs to print to the screen and handle input, it doesn't work as expected. To test this, I built this small program:
Code:
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
using namespace std;
int main() {
int x1, x2;
[code] ....
And when I use the shell I built to run it, the output is only "Enter 2 numbers" for one time. It doesn't print the result, or anything else. Is there anything I need to do in the parent process (my shell in this case) to give the child the output?
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Apr 15, 2014
I am writing a program that is supposed to open a directory as a command line argument, read that directory, open each file and count a number of occurrences of a certain character, taken from the user as cin, fork the parent process to create a child process for each file. a pipe is created for communication with the parent and a 2 dimensional array of pipes is needed for communication with each child process (each file), one for the pipe number and the other is the read/write descriptor(0 or 1). My program is looping through all the files ok, but it seems it isn't writing the "char a" to the pipe correctly. f
For every child, do_child_stuff() is called, and it reads the file name, opens it, counts the # of occurrences and returns that count to the parent to hold a total for all the files. normally to write to a pipe, it should be write(pipe_name[1], &a, sizeof(a)) but I don't know how to do this with an array of pipes. i try to write to it by doing write(child_pipe[pc][1], &a...) pc is the array position for that pipe and it gets incremented after reading each file.
struct dirent *d;
struct stat sb;
int adult_pipe[2];
int child_pipes[1000][2];
[Code]....
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Nov 13, 2013
I have an MFC application(.exe) in which i am creating an pointer object to CComQIptr<chemst::IChems>myinfo and after this i have using cocreate instance i had created the object launching that object, so Where i am using that CComQIptr object.
I have been creating instance to that COM exe (child exe) and at the end of the function i am releasing that object (myinfo->release).i want to create single instance for it and i want to use them in different .cpp files and finally i want to kill the child exe. Even though i release the object it is still alive.(Visualising in Task manager whether the exe is still alive or not).
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Jan 7, 2013
How can I create MS Word 'print layout' like interface. The attached picture says it all. Basically I want a shaded area around my document just like word so it gives a feel of the 'page'.
I was hoping I can override some function somewhere and along that lines tried playing around with below but that didn't work.
Code:
BOOL CMainFrame::PreCreateWindow(CREATESTRUCT& cs) {
if( !CFrameWndEx::PreCreateWindow(cs) )
return FALSE;
// TODO: Modify the Window class or styles here by modifying
// the CREATESTRUCT cs
cs.cx = 250; // just playing around with size
cs.cy = 250;
return TRUE;
}
How can I do that?
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Apr 8, 2014
Writing bytes to external process to remove a detour that the program does
this is what im trying it fails
HANDLE Handle = OpenProcess(PROCESS_ALL_ACCESS, false, ProcessId);
BYTE btLdrLoadDll[] = { 0x8B, 0xFF, 0x55, 0x8B, 0xEC };
if (!WriteProcessMemory(Handle, (BYTE*)((DWORD)GetProcAddress(GetModuleHandle("ntdll.dll"), "LdrLoadDll")), &btLdrLoadDll, sizeof(btLdrLoadDll), NULL)) {
CloseHandle(Handle);
std::cout << "
Failed to write Bytes to memory. Press enter to exit.";
[Code] ....
an also using the right address like this fails
WriteProcessMemory(Handle, (BYTE*)0x77C64F9F, &btLdrLoadDll, sizeof(btLdrLoadDll), NULL)
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Nov 25, 2014
I am looking into how to create zombie process. They are created when parent process don't call wait() and hence they are not removed from the process table. How do I create zombie process in C++? What part of the code when missed, make a process/thread zombie? Is it the pthread_join()?
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May 30, 2014
I have study that create a pipe and set a terminal of this pipe like a stdout of a process is a way to implement inter process comunication, but how can i do it in c++?
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Feb 13, 2014
I have a problem with creating a process and waiting until the main window of the new process was shown. I thought I can wait for it with
WaitForInputIdle(pi.hp,INFINITE);
But when the function returns, the handle of the main window of the new process is not available. If I include also a ::Sleep(), the new window is available. Sleep is a bad solution. How can I do it?
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Mar 26, 2014
I have looked through te tutorials here, and even google it, as well as tried to follow the power points from my class..but I still can't seem to figure out how to make this code work correctly.. Basically I have to create a file called grade and write to it a student name and their grade score, and then read from the file all students names and there grade and display this on the screen as well as calculate the grade average for all of the students and display it.
Well I am able to write to the text file, but I can't seem to get the rest to work. I can't figure out how to read from the text file..Here is my code below.
write a sample code that does something similar write to text file string and numbers and then reads from it.
#include <iostream>
#include <fstream>
using namespace std;
[Code].....
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Jan 25, 2015
How do i create a text file read and write in it but every time i reopen the program i must not override the data in the text file .
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Feb 24, 2014
I am writing a program that models the ups & downs of a particular stock. Everything is pretty much done, except that I need to create another event to notify that saves the following information to a file when the stock's threshold is reached: date & time, stock name, initial value & current value. I have something like this so far:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
[Code]...
I feel like i need something along the lines of
s.stockEvent += new Delegate( ???? ) in my myFile class so it know when the threshold is reached, to write the information of the current stock to the file.
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Apr 13, 2014
Say now I have a dll, loaded and run by a 32bit program. One of the things that I access from the program in the dll are several 1024x1024 int buffers. However I would like to put some data into those buffers from a external process. And I would like a separate thread in that external process for each buffer. Is there any way I can make that memory space accessible to the external process so I can use my own multi threaded memory transfers to pass that data over provided I ensure that the original process doesn't try to do anything with that data? And I would like to do this without resorting to the Read/WriteProcessMemory functions which are not threadsafe. In short, I want to set up direct memory access between the 2 programs without creating any intermediate shared memory buffers ie I want to set permissions for an existing memory space. Is this possible?
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Nov 30, 2014
I don't think my processes are being created the way I want. I'm trying to create a fan of process (i.e. one parent with multiple children).
I want the parent to put together the final output image, and the children are supposed to do the edge detection on various regions of the image. Here is what I have:
Code:
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include "iplib2New.c"
#define FILTER_SIZE 3
//Function prototypes
[Code] ......
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Mar 29, 2012
I have two command line apps, one of them is multithreaded. I need to implement a bidirectional communication between them. Currently I can do
Code:
ProgramA 1> ProgramB
for the first programA to direct output into ProgramB, however I also need ProgramB to send messages to ProgramA.
how to implement it in a easiest way.
btw, I am on Ubuntu. I'd rather not to use third party libraries, Boost, etc.
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Apr 14, 2015
how to get a list of the active processes on a computer?
What I need to do is check for a specific process to see if it's running on the system.
I just need to know if a certain process is present.
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Oct 7, 2014
I want to show all running processes of windows.
my motive is whenever any running process closes/quits whether it be console or window based on windows it notify(s) me or user that some .exe has been closed.
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Mar 2, 2014
I'm trying to use semaphores on three different processes so that each process won't enter the critical region at the same time and also go in the order: process 1 -> process 2 -> process 3. However, everytime i run the code the process 3 keeps going before process 2.
Here's my code:
#include <stdio.h>
#include <sys/types.h>
#include <sys/ipc.h>
[Code].....
the processes should print out like this:
process 1: 100000
process 2: 300000
process 3: 600000
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Jan 30, 2014
I'm working on a project that is supposed to create 3 processes. Process 1 should count from 1 to 100,000. Process 2 from 1 to 200,000. Process 3 from 1 to 300,000. I've written the basic code of it but my processes aren't printing out very accurate numbers.
Here's my code:
/*ass1*/
#include <stdio.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <stdlib.h>
#include <unistd.h>
/* change the key number */
#define SHMKEY ((key_t) 8450)
typedef struct
[code]....
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Mar 15, 2013
The Objective Of This Program Is To Create A File To Write Text And Read Back The File Content. To Do That I Have Made Two Function writeFile() To Write And readFile() To Read.The readFile() function works just fine but writeFile() doesn't.
How writeFile() function Works? when writeFile() function Execute It Takes Characters User Type And When Hit Enter(ASC|| 10) It Ask "More?(Y/N)" That Means What User Want? Want To Go Next Line Or End Input?
If "Y" Than Inputs Are Taken From Next Line Else Input Ends.
But The Problem Is When Program Encounters ch==10 It Shows "More?(Y/N)" And Takes Input In cmd variable.If cmd=='Y' I Mean More From Next Line Than It Should Execute Scanf Again To Take ch I Mean User Input.But Its Not!!! Its Always Showing "More?(Y/N)" Again And Again Like A Loop.
Code:
#include <stdio.h>
void writeFile(void);
void readFile(void);
int main(){
[Code].....
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Aug 1, 2014
I have a table in which data is populated via an element. However some elements can have a parent element
The client now wants all the children and parent elements to be next to each other row wise.
How can i add the child rows under the parent rows?
parents
foreach (var inspection in elemInspections) {
var date = db.INSPEVNT.Find(db.INSPEVNT.INSPKEY == inspection.INSPKEY && db.INSPEVNT.BRKEY == m_sBrKey);
var paircode = db.PON_ELEM_DEFS.Find(db.PON_ELEM_DEFS.ELEM_KEY == inspection.ELEM_KEY);
[Code] .....
how can i make it so the children go under the parent rows?
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Feb 5, 2014
hiclass Parent {
};
class Child : virtual public Parent {
};
What is the size of object of Class Child in following case?
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Jul 14, 2014
Right now I'm working on a TreeView for which I would like to add a TextBlock and a ComboBox as child nodes of a Parent TextBlock node. This would look something like this:
My TreeView is implemented using an MVVM style, and utilizes a HierarchicalDataTemplate. I have had no problems with adding TextBlock nodes and TextBlock children, but the confusion seems to arise when adding child nodes of different UI types.
I have tried implementing a stackPanel, like so:
<HierarchicalDataTemplate DataType="{x:Type Data:Node}" ItemsSource="{Binding Teams}">
<StackPanel>
<TextBlock Text="{Binding IndividualProperty}" />
<ComboBox ItemsSource="{Binding CollectionProperty}" />
</StackPanel>
</HierarchicalDataTemplate>
But then I end up with each node looking like this. It's like each node comes with one TextBlock and a ComboBox (Note: The comboBox is not the child, it and the TextBlock are one node):
How do I allow my treeView to have child nodes of different UI types? I am thinking that my solution has to do with my Hierarchical Data Template.
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