这文章是早期闲得用英文写的,删除了怪可惜的,贴出来证明自己会英文算了... Occasionally,on stackoverflow.com,I found a classic problem which is age-old but never to be out-dated,that is,the undefined behaviour occurred by reusing the pointer which was just deleted. The code below may be…

C语言中的未定义行为(Undefined Behavior)是指C语言标准未做规定的行为.同时,标准也从没要求编译器判断未定义行为,所以这些行为有编译器自行处理,在不同的编译器可能会产生不同的结果,又或者如果程序调用未定义的行为,可能会成功编译,甚至一开始运行时没有错误,只会在另一个系统上,甚至是在另一个日期运行失败.当一个未定义行为的实例发生时,正如语言标准所说,“什么事情都可能发生”,也许什么都没有发生. 所以,避免未定义行为,是个明智的决定.本文将介绍几种未定义行为,同时欢迎读者纠错和补充…

http://stackoverflow.com/questions/3523145/pointer-arithmetic-for-void-pointer-in-c When a pointer to a particular type (say int, char, float, ..) is incremented, its value is increased by the size of that data type. If a void pointer which points to…

1.Behaviour介绍 Erlang/Elixir的Behaviour类似于其它语言中的接口(interfaces),本质就是在指定behaviours的模块中强制要求导出一些指定的函数,否则编译时会warning. 其中Elixir中使用到behaviour的典范就是GenServer, GenEvent. 曾经Elixir有一个叫Behaviour的模块,但是在1.1时就已被deprecated掉了,现在你并不需要用一个Behaviour模块才能定义一个behaviour啦. 让我们一步…

1.zookeeper简介 zookeeper是Hadoop的子项目,在大型分布式系统中,zookeeper封装好了一些复杂易出错的服务,提供简单易用的接口,给使用者提供高效稳定的服务.这些服务包括配 置维护.名字服务.分布式同步.组服务等.当前zookeeper提供C和Java两种语言的接口,在百度实习期间参与百度开放云项目,中间的需要维护一些统一的配置,zookeeper显然 是首选的开源工具.由于能力受限,经验不足,我在项目中只是使用了zookeeper提供的配置维护的功能,其他功能有待进…

先来BOA,搬自:http://www.cl.cam.ac.uk/research/dtg/attarchive/omniORB/doc/2.8/omniORB2/node6.html The Basic Object Adaptor (BOA) This chapter describes the BOA implementation in omniORB2. The CORBA specification defines the Basic Object Adaptor as the ent…

Q: What is a dangling pointer? A: A dangling pointer arises when you use the address of an object after its lifetime is over. This may occur in situations like returning addresses of the automatic variables from a function or using the address of the…

http://stackoverflow.com/questions/3228664/why-am-i-able-to-change-the-contents-of-const-char-ptr I passed a pointer ptr to a function whose prototype takes it as const. foo( const char *str ); Which according to my understanding means that it will n…

Automake是用来根据Makefile.am生成Makefile.in的工具 标准Makefile目标 'make all' Build programs, libraries, documentation, etc. (same as 'make'). 'make install' Install what needs to be installed, copying the files from the package's tree to system-wide directories.…

src: https://wiki.edubuntu.org/ARM/Thumb2PortingHowto#ARM_Assembler_Overview When you see some assembler in a source package, there are some things which you need to consider when porting for Thumb-2 compatibility. This page aims to highlight the mai…

Question: What does copying an object mean? What are the copy constructor and the copy assignment operator? When do I need to declare them myself? How can I prevent my objects from being copied? Answer: Introduction C++ treats variables of user-defin…

C++ Core Guidelines September 9, 2015 Editors: Bjarne Stroustrup Herb Sutter This document is a very early draft. It is inkorrekt, incompleat, and pµøoorly formatted. Had it been an open source (code) project, this would have been release 0.6. Copy…

本质的原因:raw data和引用计数的管理块,可能是分开的 使用场景: 需要在对象中得到shared ptr,  错误的代码:直接构造新的shared_ptr<A>对象,两个shared_ptr objects 是独立的,pointer to the same raw mem. 两个独立的managed objects. 因此会导致undefined behaviour, delete raw data twice, 通常会导致crash. class A { public: std::sh…

Container classes are one of the cornerstones of object-oriented programming, invaluable tools that free us from having to permanently think about memory management. Qt comes with its own set of container classes, closely modeled after those in the S…

Privilege Escalation Download the Basic-pentesting vitualmation from the following website: https://www.vulnhub.com/entry/basic-pentesting-1,216/ 1.Scan the target server using nmap. nmap -Pn -sS --stats-every 3m --max-scan-delay --defeat-rst-ratelim…

原文链接:https://hashrust.com/blog/arrays-vectors-and-slices-in-rust/ 原文标题:Arrays, vectors and slices in Rust 公众号:Rust 碎碎念 翻译: Praying 引言(Introduction) 在本文中,我将会介绍 Rust 中的 array.vector 和 slice.有 C 和 C++编程经验的程序员应该已经熟悉 array 和 vector,但因 Rust 致力于安全性(safety),…

使用 gulp 编译 Sass Sass 是一种 CSS 的开发工具,提供了许多便利的写法,大大节省了开发者的时间,使得 CSS 的开发,变得简单和可维护. 安装 npm install gulp-sass (--save-dev) 括号中的可选 基本用法 Something like this will compile your Sass files: 'use strict'; var gulp = require('gulp');var sass = require('gulp-sass'…

int左移32位的行为未定义 Coverity 代码静态安全检测 Is Shifting more than 32 bits of a uint64_t integer on an x86 machine Undefined Behavior? uint64_t s = 1 << 32; uint64_t s = 1ULL << 32; Note, however, that if you write a literal that fits into 32 bits, e.g. u…

http://javarevisited.blogspot.sg/2014/05/10-articles-every-programmer-must-read.html Being a Java programmer and Software developer, I have learned a lot from articles titled as What Every Programmer Should Know about ..... , they tend to give a lot…

http://bbs.byr.cn/#!article/CPP/86336?p=1 下列代码给出输出结果: #include"stdafx.h" #include <iostream> #include "stdlib.h" using namespace std; int main(void) { ; int * p = (int *)(&a); *p = ; cout << "a = " << a…

最近玩Arduino发现,在编写函数库的时候要用到C++.正好手头有一本教材,于是时隔2年,开始重学. 又看到重载.构造.拷贝这些词竟然还有些小兴奋. 开个系列日志记录一下学习过程中的问题和体会. 看到输入输出的时候想到了C++对C的兼容性,于是试了一下printf函数. # include<iostream> # include<stdio.h> using namespace std; int main() { cout<<"C++ iostream&qu…

Declaration of variables   C++ is a strongly-typed language, and requires every variable to be declared with its type before its first use. This informs the compiler the size to reserve in memory for the variable and how to interpret its value. The s…

原地址 http://www.cplusplus.com/doc/tutorial/pointers/ Pointers In earlier chapters, variables have been explained as locations in the computer's memory which can be accessed by their identifier (their name). This way, the program does not need to care…

一.原生数据类型 JS共有5种原生数据类型: Boolean true或者false String 字符串,在单引号或者双引号之间(不存在字符类型) Number 整数或者浮点数 Null 空 undefined 未定义(一个变量没有赋值,或者 赋值为 undefined) //Boolean var flag = false; //String var str = 'Hello'; var str2 = "Hello,World"; //Number var n1 = 123; va…

Boost.Thread可以使用多线程执行可移植C++代码中的共享数据.它提供了一些类和函数来管理线程本身,还有其它一些为了实现在线程之间同步数据或者提供针对特定单个线程的数据拷贝.头文件:#include <boost/thread.hpp> 线程定义boost::thread 类是负责启动和管理线程.每个boost::thread对象代表一个单独的执行线程,是不可拷贝的.由于它是可以被移动到,所以它们可以被保存到会改变大小的容器中,并且从函数返回.这使得线程创建的详细信息可以被封装到一个函…

阅读对象 本文假设读者有几下Skills [1]在C++中至少使用过一种多线程开发库,有Mutex和Lock的概念. [2]熟悉C++开发,在开发工具中,能够编译.设置boost::thread库. 环境 [1]Visual Studio 2005/2008 with SP1 [2]boost1.39/1.40 概要 通过实例介绍boost thread的使用方式,本文主要由线程启动.Interruption机制.线程同步.等待线程退出.Thread Group几个部份组成. 正文 线程启动 线…

一个简单的程序引发了一块让人纠结的领域,也许强调编程规范的重要性也在这把.规范了就easy避免一些问题. 程序是这种 int Change(int& a) { a = 4; return a; } int main() { int a = 10; cout << Change(a) << a; } In C-Free : the output : 4 4 In VS2008 : the output : 4 10 差别出来了,按我的理解,应该C-free输出的对,可是还是探…

说到JNDI,即熟悉又陌生,熟悉在常常使用,如EJB3.0中的@EJB注入,底层实现即是JNDI的方式:喜闻乐见的: Context ctx=new InitialContext(); Object obj=(Object)ctx.lookup("java:comp/env/XXX"); 更是最经常使用的方式.说它陌生,是由于,对于JNDI,我们仅限于主要的使用,本文就是带领大家进入JNDI分析阶段. JNDI作用 以数据源为例. 未使用JNDI 假设我们没有使用JNDI,代码例如以下…

http://www.cnblogs.com/mickole/articles/3757278.html Java不能直接访问操作系统底层,而是通过本地方法来访问.Unsafe类提供了硬件级别的原子操作,主要提供了以下功能: 1.通过Unsafe类可以分配内存,可以释放内存: 类中提供的3个本地方法allocateMemory.reallocateMemory.freeMemory分别用于分配内存,扩充内存和释放内存,与C语言中的3个方法对应. public native long alloca…

1. 首先pthread_cond_wait 的定义是这样的 The pthread_cond_wait() and pthread_cond_timedwait() functions are used to block on a condition variable. They are called with mutex locked by the calling thread or undefined behaviour will result. These functions atomi…