无限递归怎么回事啊？第五个TLE，求调

void Get_Pre(char mid[8], char back[8], int len)
{
	printf("%c", back[len - 1]);
	int i;
	for (i = 0;mid[i] != back[len - 1];i++);
	char nmidl[8] = { 0 };
	char nbackl[8] = { 0 };
	char nmidr[8] = { 0 };
	char nbackr[8] = { 0 };
	int j;
	for (j = 0;j < i;j++)
	{
		nmidl[j] = mid[j];
	}
	int k = 0;
	for (j = i + 1;j < len;j++)
	{
		nmidr[k] = mid[j];
		k++;
	}
	int lenl = strlen(nmidl);
	int lenr = strlen(nmidr);
	for (j = 0;j < lenl;j++)
	{
		nbackl[j] = back[j];
	}
	k = 0;
	for (j = lenl;j < len - 1;j++)
	{
		nbackr[k] = back[j];
		k++;
	}
	if (lenl != 0)
		Get_Pre(nmidl, nbackl, lenl);
	if (lenr != 0)
		Get_Pre(nmidr, nbackr, lenr);
}