Start thread function with parameters and return value

// gcc -o thread_function thread_function.c

#include <stdio.h>
#include <pthread.h>

void* thread_function(void *parameters) {
 int number=(int)*((int*)parameters);
 printf("number=%d\n",number);
 char *a = malloc(10);
 if(number==1) strcpy(a,"<Hello World>");
 else strcpy(a,"<Good Night>");
 pthread_exit((void*)a);
 printf("After pthread_exit()\n");
}

void* startThreadFunction(void*(*start_routine)(void*),void *parameters) {
 pthread_t thread_id;
 pthread_create (&thread_id,NULL,start_routine,parameters);
 void *returnValue;
 pthread_join(thread_id,&returnValue);
 return returnValue;
}

int main(void) {
 int number;
 void *pointer;
 number=2;
 pointer=startThreadFunction(thread_function,&number);
 printf("FINAL STRING: %s POINTER: %p\n",(char*)pointer,pointer);
 number=1;
 pointer=startThreadFunction(thread_function,&number);
 printf("FINAL STRING: %s POINTER: %p\n",(char*)pointer,pointer);
}