1 #include <stdio.h>
2 #include <stdlib.h>
3 #include <pthread.h>
4 #include "common_threads.h"
5
6 typedef struct {
7 int a;
8 int b;
9 } myarg_t;
10
11 typedef struct {
12 int x;
13 int y;
14 } myret_t;
15
16 void *mythread(void *arg) {
17 myarg_t *args = (myarg_t *) arg;
18 printf("args %d %d\n", args->a, args->b);
19 myret_t *rvals = malloc(sizeof(myret_t));
20 assert(rvals != NULL);
21 rvals->x = 1;
22 rvals->y = 2;
23 return (void *) rvals;
24 }
25
26 int main(int argc, char *argv[]) {
27 pthread_t p;
28 myret_t *rvals;
29 myarg_t args = { 10, 20 };
30 Pthread_create(&p, NULL, mythread, &args);
31 Pthread_join(p, (void **) &rvals);
32 printf("returned %d %d\n", rvals->x, rvals->y);
33 free(rvals);
34 return 0;
35 }
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// bad alternative:
void *mythread(void *arg) {
myarg_t *args = (myarg_t *) arg;
printf("args %d %d\n", args->a, args->b);
myret_t oops = { 1, 2};
return &oops; // mistake, local variable deallocated on return
}
$ gcc -Wall -I../include -o thread_create_with_return_args \
thread_create_with_return_args.c -pthread
$ ./thread_create_with_return_args
args 10 20
returned 1 2
$
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