字符串匹配（BF算法）

int BF_Maching(const char* str, const char* sub) {
	assert(str != NULL);
	assert(sub != NULL);
	int len_str = strlen(str);
	int len_sub = strlen(sub);
	for (int i = 0; i < len_str; i++)
	{
		int k = i;
		for (int j = 0; j < len_sub+1; j++)
		{
			if (sub[j] == '\0')
			{
				return k - j;//返回在主串中的下标
			}
			if (str[k] == sub[j])
			{
				k++;
			}
			else
			{
				break;
			}
		}
	}
	return -1;//未找到
}

int main()
{
	const char* str = "ababcabcdabcde";
   	const char *sub = "abcd";
	int pos = BF_Maching(str, sub);
	printf("%d\n", pos);
	return 0;
}