base

Can someone explain to me why is the overridden method being called when I cast the class into the base one: class Base { public virtual void VirtualMethod() { Console.WriteLine("Base virtual method"); } } sealed class Derived : Base { public override void VirtualMethod() { Console.WriteLine("Overriden method"); } } static void Main(String[] args) { Derived d = new Derived(); ((Base)d).VirtualMethod(); } I mean this code prints: Overriden method and not Base virtual method Its a run-time or compile-time future? I know i can call the Base's virtual method from the derived by calling base

I decided to test one of the examples in "Effective C++" and I'm not getting the result I expected. So, apparently this (simplified) code shouldn't compile: template <class T> struct A { void f(){} }; template <class T> struct B : public A <T> { void f2() { f(); } // calling base function - will not compile }; Here's the explanation (class names changed for simplicity) : The code above won't compile, at least not with conformant compilers. Such compilers will complain that f doesn't exist. We can see that f is in the base class, but compilers won't look for it there. We need to understand why.

搭建本地yum仓库 m01(yum仓库) web01(客户端) 172.16.1.61 172.16.1.7 安装createrepo软件 yum(Yellow dog Updater,Modified)主要的功能是方便添加、删除和更新rpm软件包。可以解决软件包依存问题，更便于管理大量的系统更新问题。它可以同时配置多个仓库或叫资源库(repository)，就是存放更新和依存的软件包的地方。 createrepo 命令用于创建yum源（软件仓库），即为存放于本地特定位置的众多rpm包建立索引，描述各包所需依赖信息，并形成元数据。 [root@m01 base]# yum -y install createrepo -u --baseurl <url> 指定Base URL的地址 -o --outputdir <url> 指定元数据的输出位置 -p --pretty 确保生成的所有xml都格式化了 -x --excludes <packages> 指定在形成元数据时需要排除的包 -n --includepkg 通过命令行指定要纳入本地库中的包信息，需要提供URL或本地路径。 -q --quiet 安静模式执行操作，不输出任何信息。 -g --groupfile <groupfile> 指定本地软件仓库的组划分 -v --verbose 输出详细信息。 --update

Here is my code - #include<iostream> using namespace std; class base { public: void sid() { } }; class derived : private base { public: void sid() { } }; int main() { base * ptr; ptr = new derived; // error: 'base' is an inaccessible base of 'derived' ptr->sid(); return 0; } This gives a compile time error. error: 'base' is an inaccessible base of 'derived' Since the compiler will try and call the base class sid() why do I get this error? Can someone please explain this. Chubsdad $11.2/4 states- A base class B of N is accessible at R, if an invented public member of B would be a public member

•参考资料 [1]: 算法 | 线性基学习笔记 [ 2]: 线性基学习笔记 •理解 实数线性基就是n维空间的一个基底， 求线性基就是求他的基底， 也就是矩阵的最大线性无关组 可以用高斯消元来求。 异或线性基其实就是把一个数转化成二进制 转化成二进制后，最多的二进制位数就相当于他的维数 由于只有1和0，高斯消元的结果和异或的结果相同 故用异或来做可以把时间复杂度降到log •习题 洛谷P3812 【模板】线性基 (求最大) 牛客 xor序列 (查找) 洛谷P4570 [BJWC2011]元素 (插入/查找 线性基不为0) 洛谷P4301 [CQOI2013]新Nim游戏 (插入/查找 线性基不为0) 洛谷 P3265 [JLOI2015]装备购买 (实数线性基) hdu3494 XOR (第k大) cf1100F (可以用来练习区间线性基，氮素会TLE_(:з」∠)_，正解是离线做法) 洛谷P4839 P哥的桶 (线性基+线段树) 2019牛客多校第一场A (异或和为0的所有子集长度和) •初始线性基 1 ll n; 2 ll p[65]; 3 4 ///插入 5 void Insert(ll x) 6 { 7 for(int i=60;i>=0;i--) 8 { 9 if(x&(1ll<<i)) 10 { 11 if(!p[i]) 12 { 13 p[i]=x; 14 break;

Thus for used base class for some commom reusable methods in every page of my application... public class BaseClass:System.Web.UI.Page { public string GetRandomPasswordUsingGUID(int length) { string guidResult = System.Guid.NewGuid().ToString(); guidResult = guidResult.Replace("-", string.Empty); return guidResult.Substring(0, length); } } So if i want to use this method i would just do, public partial class forms_age_group : BaseClass { protected void Page_Load(object sender, EventArgs e) { //i would just call it like this string pass = GetRandomPasswordUsingGUID(10); } } It does what i want

有些时候，我们不得不处理别人用过的系统，或者是一台新安装的系统。因为安全和其它原因，系统处于最小化安装状态或者选择性安装软件包。一些常用的工具命令并没有安装。很多人的方式（包括之前的我）通过搜索引擎进行搜索答案。这样的方式效率其实并不高。我之前的博文 LINUX下借助YUM和RPM教你正确寻找并安装软件的姿势 其实并不完整。接下来，我重新谈一下完整的方法。 以下方法基于CENTOS（RHEL)系统 假设我们知道rz这个命令的用法，但系统并没有安装。这台服务器可以连接互联网或拥有私有仓库。我需要通过YUM进行查找（常用工具或软件包基本都在官方或第三方镜像源BASE，某些工具或软件需要其他第三方源） $ yum provides rz 已加载插件：fastestmirror Loading mirror speeds from cached hostfile * base: mirrors.aliyun.com * elrepo: mirrors.tuna.tsinghua.edu.cn * epel: mirrors.tuna.tsinghua.edu.cn * extras: mirrors.aliyun.com * updates: mirrors.aliyun.com lrzsz-0.12.20-36.el7.x86_64 : The lrz and lsz modem

For example. Assume I do: dev.new(width=5, height=4) plot(1:20) And now I wish to do plot(1:40) But I want a bigger window for it. I would guess that the way to do it would be (assuming I don't want to open a new window) to do plot(1:40, width=10, height=4) Which of course doesn't work. The only solution I see to it would be to turn off the window and start a new one. (Which will end my plotting history) Is there a better way ? Thanks. Some workaround could be rather than using dev.new() R function use this function which should work across platform : dev.new <- function(width = 7, height = 7)