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] .....
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] .....
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] ......
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.
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]....
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].....
I'm using windows forms and I have a parent dialog box that consists of a text box and a drop-down that launches a child dialog box. The child takes user input and then prints dialog to the text box in the parent. However, the output does not appear in the text box until I close the child.
Now my question is, how do I get the text to appear without closing the child? I hit a button to send the info to the text box, but it still doesn't appear until the child closes. I also need to set up a button to suspend the child so that the user can click/copy/etc the parent.
I have defined to classes : Parent and Child. I have some global variables in a header file named as "var.h". These variables are used in both Parent and child Classes. The source code of these classes are written below:
Parent.h
==============================================
#ifndef PARENT_H
#define PARENT_H
#pragma once
#include <stdio.h>
class Parent {
[Code] ....
After compiling, the compiler returns a fatal error as follows:
1>Parent.obj : error LNK2005: "int counter" (?counter@@3HA) already defined in Child.obj
1>C:Documents and SettingspishiDesktop estDebug est.exe : fatal error LNK1169: one or more multiply defined symbols found
It says the "counter" is defined multiple times....
I am making a very basic parent/child class based program that shows polymorphism. It does not compile due to a few syntax errors reading "function call missing argument list. Lines 76 and 77, 81 and 82, and 86 and 87.
#include<iostream>
using namespace std;
class people {
public:
virtual void height(double h) = 0;
virtual void weight(double w) = 0;
[Code] ....
I have a main dialog which has (DDX?) controls for the user. eg a slider, and a combo box.
Previously, an image adjusted by these controls was in the same dialog.
I need to put this image in a New, separate dialog but it still must be controlled by the slider and combo box on the main dialog.
My question is how can I pass the control's variables between the dialogs? I have, say,
Code:
//MainDlg.cpp
DDX_Control(pDX, IDC_ComboBrightness, m_Brightness
I was told that I could do something like:
Code:
//ImageDlg.h
public:
ImageDlg(CWnd* pParent = NULL, CComboBox m_Brightness); // standard constructor
But I get errors including: Missing default parameter for parameter 2
I also need to pass the image array, is that perhaps the same method?
I transferred data from parent to child. Problem occurred while send data from child to parent dialog.
Find the attachment....
void CChildDlg::OnBnClickedCancel() {
child1ctrl.GetWindowText(parObj.parentval);
::AfxMessageBox(parObj.parentval);
//parObj.parentctrl.SetWindowText(child1val);
[Code] ....
I am currently having an issue with a piece of code that I am writing in which I need to use a vector of a child class as a parameter in a function in the parent class. Below is an example of my code:
#include "child.h"
#include <vector>
class parent {
parent();
function(std::vector<child> children);
// rest of class here
}
When I do this my program doesn't compile. However if I try to forward declare, as shown in the following example, it once again refuses to compile:
#include <vector>
class child;
class parent{
parent();
function(std::vector<child> children);
// rest of class here
}
This time, it refuses to compile because it needs to know the full size of the class child in order to create the vector. How to being able to access the child is essential for my program, so what should I do?
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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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
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]....
I have to communicate between two laptops using USB-to-Serial adapter. I have written 2 programs one for sending and another for receiving. Programs were written in both C and C# programming languages.
Using C language: I am able to successfully communicate using C-Programs mentioned below. But the problem is speed. It takes around 1 hour(60min) for just to pass 150MB. improving the performance of this programs...I also mention some comments along with programs for self understanding.Sender File on laptop with serial port :
Code:
#include <stdio.h>
#include <bios.h>
#include <conio.h>
}
[code]....
The above 4 programs behaves as, sender send a character and receives an ack for every character. I have followed this approach, bcoz other approaches were not working fine (in the sense the complete data is not sent, the amount of data sent is not judgeable, bcoz it will different every tym). when i used this approach it worked fine.
I have a class as follows:
class testa {
public:
testa_b();
~testa_b();
testa_c();
}
Then I have defined some variables in testa_b:
testa::testa_b()
{
double aa = 1.0;
}
What is the easiest way to make testa_c() can use the aa defined in testa_b() (without declaring them in the class)?
How to communicate my COM PORT to my visual c++ ... Means i want to read data from my port and want to show in visual c++ so what to do ...
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What I have now is a producer-consumer model where producer sends a number "88" to consumer at random intervals. Now, I need consumer to send a number "99" back to producer at a random intervals, this probably should be done in a separate thread.
I am using GNU on Linux, here is the compile line.
Code:
g++ -g -std=c++11 main.cpp -o main
Code:
#include<iostream>
#include<chrono>
#include<thread>
class IObject {
public:
virtual void fromApp(int i) = 0;
virtual int toApp(int& i) = 0;// ???
[code].....
I'm trying to set up some basic communication between two programs via the registry.
For this I would like to use the functions
Code:
int value=10;
CString strSection="Data";
CWinApp* pApp = AfxGetApp();
pApp->WriteProfileInt(strSection,ValueName,value);
and
Code:
CString strSection="Data";
CWinApp* pApp = AfxGetApp();
int value=pApp->GetProfileInt(strSection,ValueName,0);
which read/write to the application's registry.
Is there some way of making two different programs use the same application registry?
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
My program allows a server and a client to chat over a socket. Currently I have to wait for one of them to type a message and press enter, before a message from the other person can be received.
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I wrote a class pedal that allows to search for the serial port on which the pedal is connected. Therefore I send a request to the pedal and set up a timer event of 20 ms. If no reply, I search for the next serial port.
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Now if the pedal is disconnected then connected again I would like it to run again.
Therefore I set another timer event every 2s that launches all what I described above.
The trouble comes because the 20 ms timer event doesn't run and I do not understand why.
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