C / C++ / MFC

#include <stdio.h><br />
//#include <sys/types.h>                                                                                                     <br />
#include <sys/stat.h><br />
#include <stdlib.h><br />
#include <pthread.h><br />
<br />
void* increment(void *msg);<br />
<br />
int count = 0;<br />
int num[1];<br />
pthread_mutex_t mutex;// = PTHREAD_MUTEX_INITIALIZER;                                                                        <br />
<br />
int main()<br />
{<br />
//int num [1];                                                                                                                <br />
  FILE *f;<br />
  f=fopen("data.txt","w");<br />
  num[0]=0;<br />
  fwrite(num,sizeof(num),1,f);<br />
  fclose(f);<br />
<br />
  pthread_t t1, t2, t3, t4, t5;<br />
  pthread_mutex_init(&mutex,NULL);<br />
  int tid1, tid2, tid3, tid4, tid5;<br />
  char msg1[] = "Thread 1";<br />
  char msg2[] = "Thread 2";<br />
  char msg3[] = "Thread 3";<br />
  char msg4[] = "Thread 4";<br />
  char msg5[] = "Thread 5";<br />
<br />
   pthread_attr_t *attr;<br />
   pthread_attr_init(attr);<br />
  tid1 = pthread_create( &t1, NULL, increment, (void*)msg1);<br />
  tid2 = pthread_create( &t2, NULL, increment, (void*)msg2);<br />
  tid3 = pthread_create( &t3, NULL, increment, (void*)msg3);<br />
  tid4 = pthread_create( &t4, NULL, increment, (void*)msg4);<br />
  tid5 = pthread_create( &t5, NULL, increment, (void*)msg5);<br />
<br />
  printf("Threads are created!\n");<br />
<br />
  pthread_join(t1, NULL);<br />
  pthread_join(t2, NULL);<br />
  pthread_join(t3, NULL);<br />
  pthread_join(t4, NULL);<br />
  pthread_join(t5, NULL);<br />
<br />
  return 0;<br />
<br />
}<br />
<br />
<br />
void *increment(void* msg)<br />
{<br />
 char *message = (char*)msg;<br />
  printf("%s starts: ", message);<br />
  for (int i=0;i<20;i++)<br />
    {<br />
      pthread_mutex_lock( &mutex );<br />
      FILE* fh = fopen("data.txt", "r+");<br />
      fread(num, sizeof(num), 1, fh);<br />
      num[0] = num[0]+1;<br />
      printf("%d\n", num[0]);<br />
      fseek(fh,0,SEEK_SET);<br />
      fwrite(num, sizeof(num), 1, fh);<br />
      fclose(fh);<br />
      pthread_mutex_unlock( &mutex );<br />
    }<br />
   pthread_exit(NULL);<br />
}<br />
<br />