Passing Parameters to pthread_create

#include

#include <pthread.h>

using namespace std;

pthread_t thread;

void *fn(void *arg)
{
int i = *(int *)arg;
cout << "i = " << i << endl;

return ((void *)0);  

}

int main()
{
int err1;
int i = 10;

err1 = pthread_create(&thread, NULL, &fn, &i);  
pthread_join(thread, NULL);  

}

————————————————————————————————

Thread creation function:
int pthread_create(pthread_t *tid, const pthread_attr_t *attr, void *(*func)(void *), void *arg);
The parameter func represents a function that takes one void * argument and returns a void *;
For the void *arg parameter, under gcc 3.2.2, both of the following methods can be compiled successfully.
int ssock;
int TCPechod(int fd);

1. pthread_create(&th, &ta, (void ()(void *))TCPechod, (void *)ssock);
2. pthread_create(&th, &ta, (void ()(void *))&TCPechod, (void *)&ssock);

Original post from ChinaUnix blog, please click here to view the original: http://blog.chinaunix.net/u/9643/showart_49987.html

pthread_create(&tid, &attr, &func, (void)arg) can only pass one argument to func. What if more than one argument needs to be passed? Please advise.

Define a structure and pass the structure

Can multiple parameters be passed to the thread function in pthread_create?

CODE:

typedef union {
size_t arg_cnt;
any_possible_arg_types;
} arg_type;

arg_type args[ARG_NUM + 1];
args[0].arg_cnt = ARG_NUM;
args[1].xxx = ...;

pthread_create (..., ..., thread_function, &args[0]);

Parse them inside the function.

-------------------------

Usage of Passing Parameters in pthread_create

Recently, I started writing socket programs again.
Instead of using select or the old heavy-weight fork approach,
this time I'm using pthreads to handle requests received on the server side.
However, there's one issue: how to pass parameters to the thread handler?
Checking man pthread_create, you'll see only the 4th argument can be used.
As for how to use it, I looked up some old sample code — turns out, casting works.

No problem with strings; for passing an integer, write it like this:

void pfunc (void *data)
{
int i = (int)data;
...
}

main()
{
int ival = 100;
pthread_t th;
...
pthread_create(&th, NULL, pfunc, (void *)ival);
}

When dealing with multiple parameters, just pack them into a struct and pass the pointer:

struct test
{
int no;
char name[80];
};

void pfunc (void *data)
{
struct test tt = (struct test)data;
...
}

main()
{
struct test itest;
pthread_t th;
...
itest.no = 100;
strcpy(itest.name, "Hello");
...
pthread_create(&th, NULL, pfunc, (void *)&itest);
...
}