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1.环境 win7 x64，oracle 11g r2，jdk6 x64 2.问题 第一次启动Oracle SQL Developer的时候会让我们填写java.exe的路径，我在jdk安装目录下的bin中找到了java.exe，但是填写以后报如下错误： 3.原因 oracle 11g中安装的Oracle SQL Developer是32位的，而我们现在给他指定的java.exe却是64位的，所以会出现这种错误。 4.解决方法 1）从网上下载Oracle SQL Developer x64，然后替换原目录：D:\app\oracle\product\11.1.0\db_1\sqldeveloper下的32位的Oracle SQL Developer。这样重新启动Oracle SQL Developer 并制定java.exe的路径就可以了。 2）安装JDK6 x86，也就是32位的JDK，虽然我们的系统是64位的，但是也兼容32位的JDK。 上述两种方法均试过，都可以正常运行。 来源： oschina 链接： https://my.oschina.net/u/941309/blog/106531

今天安装完SenchaCmd 还没来得及爽爽呢 一打开黑窗口 键入sencha 傻眼了。。。不知道神马情况 进入sencha目录 啊哈~ 看到一个sencha.jar 计上心来 怪不得在这之前要安装jre环境呢 新建一个mysencha.bat文件，内容如下： cd C:\Users\xue777hua\bin\Sencha\Cmd\3.1.1.274 java -jar sencha.jar %* 打开一个黑窗口，键入mysencha help generate app 哈哈 成功了！ 这个SenchaCmd刚出来没多久，对windows平台的支持不是太好，也值得理解。 后续：后来发现了当前环境变量中有 SENCHA_CMD_3_0_0=C:\Users\xue777hua\bin/Sencha/Cmd/3.1.1.274 故而mysencha.bat代码升级为 java -jar %SENCHA_CMD_3_0_0%\sencha.jar %* 来源： oschina 链接： https://my.oschina.net/u/854191/blog/132057

I. Handle classes #include <string> #include <memory> class PersonImpl; class Date; class Address; class Person { public : Person( const std :: string & name, const Date& birthday, const Address& addr); std :: string name() const ; std :: string birthDate() const ; std :: string address() const ; private : std ::tr1:: shared_ptr <PersonImpl> pImpl; }; #include "Person.h" #include "PersonImpl.h" class RealPerson; Person::Person( const std :: string & name, const Date& birthday, const Address& add): pImpl( new PersonImpl(name, birthday, addr)) { } std :: string Person::name const { return pImpl-

Friends, I saw this article by Ingo Molnar, a famous Linux Kernel enthusiast where he talks about 4GB/4GB split. In this article he says that with the 4G/4G patch, the kernel can be compiled in 4G/4G mode, in which case there's a full, separate 4GB VM for the kernel, and there are separate full (and per-process) 4GB VMs for user-space. My problem starts here: My assumption was that in a monolithic kernel like as in Linux, the kernel and user part of process shares same PROCESS ADDRESS SPACE. So with a Linux kernel that does not have this 4G/4G patch, we have 3/1 split for user virtual space

This question already has an answer here: call to pure virtual function from base class constructor 6 answers class a //my base class { public: a() { foo(); } virtual void foo() = 0; }; class b : public a { public: void foo() { } }; int main() { b obj; //ERROR: undefined reference to a::foo() } Why it gives me error? The pure virtual foo is defined. What do I need to change in my code to make it work? I need pure virtual method from base class be called in its constructor. Calling virtual functions in a constructor is recognised as a bad thing to do . During base class construction of a

I'm trying to override an abstract method in an abstract class with a virtual method in a child class. I (assumed until now?) understand the difference between abstract and virtual methods. Obviously I'm not able to do it but my question is... why? Based on the accepted answer here and the following scenario, I just don't see the problem: public abstract class TopLevelParent { protected abstract void TheAbstractMethod(); } public class FirstLevelChild1 : TopLevelParent { protected override void TheAbstractMethod() { } } public class FirstLevelChild2 : TopLevelParent { protected virtual

I have the following relation of classes. I want to clone the class Derived, but I get the error "cannot instantiate abstract class". How I can clone the derived class? Thanks. class Base { public: virtual ~Base() {} virtual Base* clone() const = 0; }; class Derived: public Base { public: virtual void func() = 0; virtual Derived* clone() const { return new Derived(*this); } }; Only concrete classes can be instantiated. You have to redesign the interface of Derived in order to do cloning. At first, remove virtual void func() = 0; Then you will be able to write this code: class Base { public:

多态性与虚函数 多态性 (函数重载，运算符重载就是多态性现象) 多态性 ：向不同对象发送同一个消息，不同对象在接收时会产生不同的行为。（每个对象用自己的方式去响应共同的消息） 多态性又可以分为静态多态性和动态多态性 静态多态性 在编译时编译系统就可以判定调用哪个重载运算符（函数）。 #include<iostream> using namespace std; class point { public: point(float a, float b) { //构造函数 x = a; y = b; } friend ostream & operator <<(ostream &, point &); //运算符重载 protected: float x, y; }; std::ostream &operator<<(std::ostream &output, point &p) { //运算符重载的定义 output << "(" << p.x << "," << p.y << ")" << endl; return output; } class circle :public point { public: circle(float a, float b, float c) :point(a, b), radius(c) {} //构造函数 friend ostream