• Extroverts get their turn!
• Online version is what's presented below is right here.

static const char *kExtroverts[] = {
  "Albert Chon",
  "John Carlo Buenaflor",
  "Jessica Guo",
  "Lucas Ege",
  "Sona Allahverdiyeva",
  "Yun Zhang",
  "Tagalong Introvert Jerry Cain"
};
static const size_t kNumExtroverts = sizeof(kExtroverts)/sizeof(kExtroverts[0]) - 1;

static void *recharge(void *args) {
  const char *name = kExtroverts[*(size_t *)args];
  printf("Hey, I'm %s.  Empowered to meet you.\n", name);
  return NULL;
}

int main() {
  printf("Let's hear from %zu extroverts.\n", kNumExtroverts);
  pthread_t extroverts[kNumExtroverts];
  for (size_t i = 0; i < kNumExtroverts; i++)
    pthread_create(&extroverts[i], NULL, recharge, &i);  
  for (size_t j = 0; j < kNumExtroverts; j++)
    pthread_join(extroverts[j], NULL);
  printf("Everyone's recharged!\n");
  return 0;
}

Here are a few (clearly broken) sample runs:

poohbear@myth12:$ ./confused-extroverts 
Let's hear from 6 extroverts.
Hey, I'm John Carlo Buenaflor.  Empowered to meet you.
Hey, I'm Jessica Guo.  Empowered to meet you.
Hey, I'm Sona Allahverdiyeva.  Empowered to meet you.
Hey, I'm Sona Allahverdiyeva.  Empowered to meet you.
Hey, I'm Yun Zhang.  Empowered to meet you.
Hey, I'm Tagalong Introvert Jerry Cain.  Empowered to meet you.
Everyone's recharged!
poohbear@myth12:$ ./confused-extroverts 
Let's hear from 6 extroverts.
Hey, I'm Sona Allahverdiyeva.  Empowered to meet you.
Hey, I'm Tagalong Introvert Jerry Cain.  Empowered to meet you.
Hey, I'm Tagalong Introvert Jerry Cain.  Empowered to meet you.
Hey, I'm Tagalong Introvert Jerry Cain.  Empowered to meet you.
Hey, I'm Tagalong Introvert Jerry Cain.  Empowered to meet you.
Hey, I'm Tagalong Introvert Jerry Cain.  Empowered to meet you.
Everyone's recharged!
poohbear@myth12:$

• Note that recharge references its incoming parameter this time, and that pthread_create accepts the location of the surrounding loop's index variable via its fourth argument. pthread_create's fourth argument it always passed verbatim as the single argument to the thread routine.
• The problem: The main thread advances i without regard for the fact that i's address was shared with each of the six child threads.
• At first glance, it's easy to assume that pthread_create captures not just the address of i, but the value of i itself. That assumption would be incorrect, as it copies the address and that's all.
• The address of i (even after it goes out of scope) is constant, but its contents evolve in parallel with the execution of the six recharge threads. *(size_t *)args takes a snapshot of whatever i just happens to be at the time it's evaluated.
• This is a simple example of what's called a race condition.