what is the error C4996 means? : there is a simple case of C++
    
    #include <cstring>
    using namespace std;

    int main(int argc, _TCHAR* argv[])
    {
	char str[80];
	cout << "輸入字串：";
	gets(str);
	cout << "輸入的字串：" << str << endl;
	return 0;
    }

when click running there is a error

"错误1  error C4996: 'gets': This function or variable may be unsafe.
        Consider using gets_s instead. To disable deprecation, 
        use _CRT_SECURE_NO_WARNINGS. See online help for details."