…
10│ struct myIO {FILE *in; FILE *out;};
11│ void* threadFunc(void *num);
  …
17│ struct {
18│   pthread_mutex_t mtx;
19│   char text[256];
20│ } item[5];
21│
22│ int main(int argc, char **argv) {
  …
28│   for (intptr_t i = 1; i < 5; ++i) {
29│     pthread_t tid;
30│     pthread_create(&tid, NULL, threadFunc, (void *)i);
31│     pthread_detach(tid);
32│   }
33│   threadFunc(0);
34│ }
35│
36│ void *threadFunc(void* numRaw) {
37│   intptr_t num = (intptr_t) numRaw;
38│   struct myIO win = openWin(num);
  …
48│   while (1) {
49│     fprintf(win.out, "> ");
50│
51│     char line[1024];
52│     fgets(line, 1024, win.in);
53│     line[strlen(line)-1] = 0;
54│
55│     int argOne = atoi(line);
  …
61│     char *argTwoTxt = strchr(line, ' ');
62│
63│     if (!argTwoTxt) {
65│       pthread_mutex_lock(&item[argOne].mtx);
66│       fprintf(win.out, "T#%ld reads %d as: %s\n", num, argOne, item[argOne].text);
67│       pthread_mutex_unlock(&item[argOne].mtx);
68│       continue;
69│     }
70│
71│     argTwoTxt++;
72│     char *e;
73│     int argTwo = strtol(argTwoTxt, &e, 10);
74│
75│     if (!*e && argTwo < 5 && argTwo >= 0 && argOne != argTwo) {
77│       pthread_mutex_lock(&item[argOne].mtx);
78│       pthread_mutex_lock(&item[argTwo].mtx);
79│       fprintf(win.out, "T#%ld copies %d to %d\n", num, argTwo, argOne);
80│       memcpy(item[argOne].text, item[argTwo].text, sizeof(item[argOne].text));
81│       pthread_mutex_unlock(&item[argTwo].mtx);
82│       pthread_mutex_unlock(&item[argOne].mtx);
83│     } else {
85│       pthread_mutex_lock(&item[argOne].mtx);
86│       fprintf(win.out, "T#%ld assigns to %d the value: %s\n", num, argOne, argTwoTxt);
87│       memset(item[argOne].text, 0, sizeof(item[argOne].text));
88│       strncpy(item[argOne].text, argTwoTxt, sizeof(item[argOne].text) - 1);
89│       pthread_mutex_unlock(&item[argOne].mtx);
90│     }
91│   }
92│ }
  …