UNIX for Dummies Questions & Answers

Hi,

I'm trying to do my homework assignment but I am having trouble using the pthread_create fucntion.

Here is my code________________

//Alicia Johnson
//sum_pid program
//creates n number of threads. These threads create a random number
//then adds the number to a global array. Then a for loop iterates through the array
//and adds the numbers together. The sum is outputted

#include<iostream>
#include<pthread.h>
#include<stdlib.h>



void sum_pid(int n){

int i; //counter to print numbers

int total; //counter that holds the sum of all the numbers added together

int sum[n]; //array that holds the random numbers that are genreated


for(i=0; i<n; ++i){

int random=rand() % 10 + 1;

std::cout<<

"This thread has the number "<<random<<std::endl;
sum[i]=random;

if(i==n-1){

for(int j=0; j<n; ++j){

total=total + sum[j];

}

std::cout<<"The sum of the threads is "<<total<<std::endl;

}

}
//term
inate thread
pthread_exit(NULL);



}


int main(int argc, char *argv[]){

int thr_id; //thread id for the newly created thread

int n; //the number of threads to be created

pthread_t p_thread; //threads structure

//Ask the user for number of threads to create
std::cout<<"Enter number: "<<std::endl;
std::cin>>n;


//create a new thread that will execute 'sum_pid()'
thr_id = pthread_create(&p_thread, NULL, (void*)&sum_pid),(void *)&n);

return 0;

}

Here is my Homework Description:

Write a unix pthread program sum_pid that will take
an integer command line argument n, spawn n
threads that will each generate a random number
between -100 and 100, print out their random
number, and then compute and print out the sum of
random numbers.

When I run the program i get these error messages:

Homework3.cpp: In function âint main(int, char**)â:
Homework3.cpp:58: error: invalid conversion from âvoid*â to âvoid* (*)(void*)â
/usr/include/pthread.h:227: error: too few arguments to function âint pthread_create(pthread_t*, const pthread_attr_t*, void* (*)(void*), void*)â
Homework3.cpp:58: error: at this point in file
Homework3.cpp:58: error: expected `;' before â)â token
Homework3.cpp:60: error: expected primary-expression before âreturnâ
Homework3.cpp:60: error: expected `)' before âreturnâ

I have asked my teacher how do I write it in C++ but he only knows how to make it work in C. Please can someone help me.

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