$ gcc -o thread2 thread2.c -lpthread
thread2.c:10: error: two or more data types in declaration specifiers
thread2.c: In function ‘main’:
thread2.c:29: warning: passing argument 3 of ‘pthread_create’ from incompatible pointer type
thread2.c:33: warning: passing argument 3 of ‘pthread_create’ from incompatible pointer type