C语言产生随机字符串

#include <stdio.h>
#include <Windows.h>

//产生长度为length的随机字符串  
int genRandomString(int length,char* ouput)
{
	int flag, i;
	srand((unsigned)time(NULL));
	for (i = 0; i < length - 1; i++)
	{
		flag = rand() % 3;
		switch (flag)
		{
		case 0:
			ouput[i] = 'A' + rand() % 26;
			break;
		case 1:
			ouput[i] = 'a' + rand() % 26;
			break;
		case 2:
			ouput[i] = '0' + rand() % 10;
			break;
		default:
			ouput[i] = 'x';
			break;
		}
	}
	return 0;
}

int main()
{
		char line[32] = {0};
		memset(line, 0, 32);
		genRandomString(16, line);
		printf("line=%s\n", line);
		memset(line, 0, 32);
		Sleep(1000);
		genRandomString(16, line);
		printf("line=%s\n", line);
}