毫秒爲單位產生隨機數

秒作爲隨機數，可能會重複

採用毫秒級別

#include <stdio.h>
#include <time.h>
#include <stdlib.h>
 
#define SIZE 10
 
void get_rand(char *p,  int length) {	
	int i;
	unsigned int seed;
	char value[] = "0123456789abcdef";
	struct timeval cur_t;

	gettimeofday(&cur_t, NULL);
	printf("sec:%d uc:%d\n", cur_t.tv_sec, cur_t.tv_usec);
	
	seed = cur_t.tv_sec*1000 + cur_t.tv_usec;
	
//	srand(time(NULL));
	srand(seed);
	for ( i = 0; i < length; ++i) 
        {
	    *(p + i) = value[rand() % 16];
	}
	*(p + length) = '\0';
	return;
}
int main() 
{
	unsigned char value[SIZE+1] = {0}; 
	get_rand(value, SIZE);
	printf("value is: %s, %d\n", value, value[SIZE]);
	return 0;
}