this is my first post. I have a task to use a fork to create multiple processes and then use execlp to run another program to add 2 numbers.
The problem I am having is we are supposed to use the exit() call in the execlp to return the small integer. This is a bad way to communicate but it's what we are supposed to do for the sake of this program.
Here is my "coordinator" program
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdlib.h>
using namespace std;
int main (int argc,char* argv[])
{
const int size = argc-1;
int sizeArray = 0;
int numofProc =0;
int arrayofNum[size];
int status;
int value;
for(int y=1; y<argc; y++)
{
arrayofNum[y-1] = atoi(argv[y]);
sizeArray++;
}
if(sizeArray % 2 !=0)
{
arrayofNum[sizeArray] = 0;
sizeArray++;
}
numofProc = sizeArray/2;
//declaration of a process id variable
pid_t pid;
//fork a child process is assigned
//to the process id
pid=fork();
//code to show that the fork failed
//if the process id is less than 0
if(pid<0)
{
cout<<"Fork Failed";// error occurred
exit(-1); //exit
}
//code that runs if the process id equals 0
//(a successful for was assigned
else
if(pid==0)
{
//this statement creates a specified child process
execlp("./worker", "worker", arrayofNum[0], arrayofNum[1]);//child process
}
//code that exits only once a child
//process has been completed
else
{
waitpid(pid, &status, 0);
cout<<status;
}
//main
}
and here is the execlp process
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
using namespace std;
int main(int argc, char* argv[])
{
int arrayofNum[argc-1];
arrayofNum[0] = atoi(argv[1]);
arrayofNum[1] = atoi(argv[2]);
int sum = arrayofNum[0] + arrayofNum[1];
exit(sum);
}
My problem is NO MATTER WHAT I DO, the status is ALWAYS printing a 0, I do not know how to retrieve the sum that is returned from the worker process.
My professor told me ""Only the higher byte of status will have the value returned by the worker. you need to extract it. It can be done by many ways. ""
In a nut shell, my question is, How do I retrieve that "sum" that is being sent from my worker process.
Please, I am so confused and have been up for 2 nights wondering about this
Thanks,
John