游标在Oracle PRO*C中的使用方法及技巧

PL/SQL语言一般局限于对数据库的操作，本身不是计算完备的语言，如在变量类型上不仅高级程序设计语言(如：C语言)有如数组、指针等一些复杂交量类型；另外该语言是面向集合的语言(set-oriented languase)，即执行一条语句可以一次性地提供所需的所有元组，可是在实际编程时我们需要对这些元组逐个地赋值给相关变量，根据条件分别处理。目前解决此类问题办法是将PL／SQL语言嵌入到高级程序设计语言中，利用高级程序设计语言处理数据能力强的优点，与PL/SQL语言对数据库直接操作的特点相结合，共同完成，这在一定程度上，既增加编写程序的难度，又使整个程序繁琐。下面我向大家介绍在ORACLE数据库中，增加的工具游标，使用它可以方便地实现将多行查询结果进行逐行处理。     

PowerBuilder中的Watcom C＋＋Builder的应用

我们用PowerBuilder开发应用系统,多数可以用PowerBuilder自身提供的函数实现,但遇到图像处理、复杂的逻辑和科学运算时,单靠PowerBuilder的自身功能就有些力不从心了。如果选用C或C++语言来实现极为容易,可喜的是PowerBuilder内嵌有Watcom C++Class Builder,它是一种C++语言编译器,选用它来解决PowerBuilder自身不易实现的功能,显得十分简单,使用也较方便。     

C＋＋Builder3.0编程技巧与实践（五）——多媒体创意实践

C＋＋Builder30中提供了诸如图形、图象、声音、视频等多媒体信息的强大处理功能，特别是C＋＋Builder中经过封装好了的TMediaP切er控件，它可以直接调用Windows系统提供的100多个具有多媒体处理能力的API函数，再借助C＋＋Builder的高效、可视化开发环境和具有强大功能的C＋十语言，可以非常容易地实现多媒体应用程序的汗发。百变国帝的开发利用C＋＋Builder30提供的Splitter分割条）控件和Iamge（图象框部件）可以开发一个随时更换窗帘和窗口背景图象的百叶窗演示程序（图1）：回1程序演示时，用鼠标拖动两个图象（一个做百叶窗的…     

面向对象的并行消息传递库的设计与实现分析

MPI是并行程序设计中广泛使用的一个消息传递库，虽然标准MPI-2定义了C 绑定，但它并不严格符合面向对象的观点。在分析各类已有面向对象消息传递系统的基础上，用C 设计并实现了一个面向对象的、易于传递对象(包括用户自定义类型和STL容器)的、MPI一致的、类型安全的、基于MPI的并行消息传递库，并给出了相应的使用实例及性能分析。     

C/C++静态代码安全检查工具研究

静态代码安全检查工具是一种能够帮助程序员自动检测出源程序中是否存在安全缺陷的软件。它通过逐行分析程序的源代码，发现软件中潜在的安全漏洞。本文针对C／C＋＋语言程序设计中容易存在的多种安全问题，分别分析了问题的根源，给出了具体可行的分析及检测方法。最后通过对静态代码安全检查工具优缺点的比较，给出了一些提高安全检查效果的建议。     

C＋＋模板类型系统Concepts初探

介绍了C＋＋标准为了适应泛型编程的大规模运用，在语言核心方面对泛型编程能力将要作出的改进，概述了C＋＋模板类型系统Concepts的主要功能和语言要素以及标准库支持，并给出一些例子进行说明。最后，简单介绍了现有的Concepts实现。     

C＋＋语言中静态数据成员和静态成员函数的研究

本文深入分析了C＋＋语言中类静态数据成员和静态成员函数的作用以及声明和访问方法，指出了程序设计中利用全局变量来实现数据共享的弊端，同时给出了解决方案，也指出了静态成员函数访问非静态成员的解决方法，并举了相应的实例来说明如何正确使用静态数据成员和静态成员函数。     

面向对象的C++程序设计中各类对象初始化方法

通过对C＋＋语言的充分挖掘和实践，本文总结了不同类型对象的初始化方法，在此基础上，阐述了嵌套类和复合类等复杂类对象的初始化过程，并给出实例说明，运用所述方法，实现了各类对象正确，高效地初始化，从而为对象的正常运作奠定了坚实基础。     

如何基于Java实现数据结构链表相关程序

链表是一种重要的数据结构，在程序设计中占有很重要的地位。C语言和C＋＋语言中是用指针来实现链表结构的，由于Java语言不提供指针，所以有人认为在Java语言中不能实现链表，其实不然，Java语言比C和C＋＋更容易实现链表结构。Java语言中的对象引用实际上是一个指针，所以可以编写这样的类来实现链表中的结点。这个程序（程序运行环境：j2sdkl．4．2）就是把链表的遍历、倒链、排序、删除接点等方法结合到了一起。     

基于C++17的泛型函数容器实现方法研究

泛型函数容器的使用可以解耦对象之间的调用关系,有利于实现高内聚、低耦合的软件设计原则。C++标准库中并没有这样的容器,用C++旧标准实现也很困难、很低效。C++1x等新标准发布后,出现了一些更好的实现方式。本文将在已有设计的基础之上,基于C++17新标准,利用ifconstexpr、foldexpression、std::invoke等新技术,提供一种泛型函数容器的实现方式。测试表明该实现方式简洁高效,解决了重载函数和某些特殊函数的注册调用问题,可以显著降低耦合性、提高代码复用性。     

基于属性综合评价系统的漏洞静态严重性评估

针对计算机安全漏洞的静态严重性评估问题,提出了一种基于属性综合评价系统的漏洞静态严重性分析方法。该方法从漏洞的基本属性中提取漏洞的威胁性、影响度、流行性和修补难易4个指标,运用属性综合评价系统理论评价其静态严重性,获得二元组表示的漏洞静态严重性,其中的定性表示值表示漏洞的静态严重性等级,定量表示值表示漏洞静态严重性分值。应用实例表明该方法对于漏洞静态严重性的评估是准确有效的。相比于现有的漏洞严重性分析方法,该方法兼备了定性和定量表示的优点,体现了同一级别之下不同漏洞的静态严重性的细微差别     

A recursive model for static empty container allocation

Backlogged empty containers have gradually turned into a serious burden to shipping networks. Empty container allocation has become an urgent settlement issue for the container shipping industry on a global scale. Therefore, this paper proposes an improved immune algorithm based recursive model for optimizing static empty container allocation which integrates with the global maritime container shipping network. This model minimizes the operating and capital costs during container shipping considering 0–1 mixed-integer programming. So an immune algorithm procedure based on a special twodimensional chromosome encoding is proposed. Finally, computational experiments are performed to optimize a 10-port static empty container shipping system. The results indicate that the proposed recursive model for static empty container allocation is effective in making an optimal strategy for empty container allocation.     

基于XML的动态数据报表生成技术

在企业应用中,通常都涉及到大量数据报表的处理。本文根据典型的企业信息系统,提出一种使用XML作为数据组织媒介,通过XSL转换器,套用按照静态HTML模版书写的XSLT文件,动态生成HTML文档形式的数据报表的方法。     

From Flow Logic to static type systems for coordination languages

Coordination languages are often used to describe open-ended systems. This makes it challenging to develop tools for guaranteeing the security of the coordinated systems and the correctness of their interaction. Successful approaches to this problem have been based on type systems with dynamic checks; therefore, the correctness properties cannot be statically enforced. By contrast, static analysis approaches based on Flow Logic usually guarantee properties statically. In this paper, we show how the insights from the Flow Logic approach can be used to construct a type system for statically ensuring secure access to tuple spaces and safe process migration for an extension of the language Klaim.     

Mathematical modeling of yard template regeneration for multiple container terminals

As a tactical-level plan, the yard template determines the space allocation in a container terminal yard for all the arriving shipping liners. Generally speaking, the yard template will not change and it may last a matter of years. However, it has to be changed to response to the alteration of shipping liner. This paper investigates the problem of yard template regeneration for container port, which contains multiple container terminals. Firstly, the concept of yard template regeneration as well as the main influencing factors is proposed. Secondly, a multiple-objective mixed integer programming model is formulated which fully considering the minimum transportation cost, minimum template disturbance and maximum space utilization. Moreover, a case study is conducted to intuitively illustrate the regeneration problem of yard template. Finally, performance analysis and sensitivity analysis are performed to validate the effectiveness of the model.     

CAR包容技术的设计与实现

传统构件技术的包容都是静态的,这显然不利于使用,而设计一种动态包容技术将大大增加构件的灵活性。基于CAR构件设计并实现了一种动态包容技术,此技术充分利用了CAR的基于二进制的AOP编程模型,将包容器设计成方面构件类AObjectContainer,从而使聚合了AObjectContainer的普通构件类轻松地具有了包容能力。此方法具有使用简单,可动态控制被包容对象等特点。     

改进的JDBC框架在数据持久层的应用

为了解决面向构建企业级系统的JDBC数据持久化的问题,详细分析了模板模式和策略模式,并通过这两种设计模式改进了JDBC框架,最终形成了改进后的JDBC扩展框架,它具有不依赖于任何的O/R映射框架和EJB容器,且易学习、易使用、易部署等特点.最后,结合某个电信客户关系管理系统(CRM)中的车辆管理模块的开发,给出了具体的实现.实验结果表明,改进后的JDBC框架有较强的实用性和有效性.     

WCL: A co-ordination language for geographically distributed agents

In this paper a tuple space based co-ordination language, and a run-time system which supports it, is described. The co-ordination language is called WCL, and it is designed to support agent co-ordination over the Internet between agents which are geographically distributed. WCL uses tuple spaces as used in Linda. WCL provides a richer set of primitives than traditional tuple space based systems, and provides asynchronous and synchronous tuple space access, bulk tuple primitives, and streaming primitives which, as a whole, provide a complete framework more suited to co-ordination over the Internet compared with the Linda primitives. The primitives emphasise efficiency and location transparency (of data and agents) and this is exploited in the current run-time system used to support WCL. The run-time system described in this paper is distributed and uses location transparency and dynamic analysis of tuple space usage to migrate tuple spaces around the distributed system. Some initial experimental results are given which demonstrate the performance gains of using the tuple space migration. The paper motivates the inclusion of many of the primitives, and demonstrates how a well designed set of primitives provides performance and efficiency. The JavaSpace primitives are used as an example of how the choice of primitives can detrimentally affect the efficiency of the language, and exclude required co-ordination constructs.     

STL关键特征及其实现方法

标准模版库提供了一系列的容器类型,使用容器可以完成任意类型对象的不限量存储。任何模版类型中均包含迭代器类型,使用迭代器类型可以完成统一的指针操作,读写容器内的数据。不同模版具有不同的存储结构,实际应用中存在性能差异。     

Supporting fault-tolerant parallel programming in Linda

Linda is a language for programming parallel applications whose most notable feature is a distributed shared memory called tuple space. While suitable for a wide variety of programs, one shortcoming of the language as commonly defined and implemented is a lack of support for writing programs that can tolerate failures in the underlying computing platform. This paper describes FT-Linda, a version of Linda that addresses this problem by providing two major enhancements that facilitate the writing of fault-tolerant applications: stable tuple spaces and atomic execution of tuple space operations. The former is a type of stable storage in which tuple values are guaranteed to persist across failures, while the latter allows collections of tuple operations to be executed in an all-or-nothing fashion despite failures and concurrency. The design of these enhancements is presented in detail and illustrated by examples drawn from both the Linda and fault-tolerance domains. An implementation of FT-Linda for a network of workstations is also described. The design is based on replicating the contents of stable tuple spaces to provide failure resilience and then updating the copies using atomic multicast. This strategy allows an efficient implementation in which only a single multicast message is needed for each atomic collection of tuple space operations