PCB钻铣机CAD/CAM集成数控系统的设计与开发

介绍PCB钻铣机CAD/CAM集成数控系统的设计与开发的若干关键技术及其实现的方法。该系统主要解决印刷线路板加工中的图形设计、前/后置处理、路径优化和钻铣机数控系统等实用问题,目前已成功应用于多家印刷线路板生产厂和钻铣机生产厂。     

MAP: A Pascal macro preprocessor for large program development

The programming language Pascal was originally designed for teaching introductory programming. Currently, however, production systems use it as the primary implementation language. This paper describes extensions of Pascal intended to aid the large program developer. The extensions are implemented in a macro preprocessor MAP, which supports constant expression evaluation, source file inclusion, conditional compilation and macro substitution. While each of these features can be used independently, they are all implemented with a simple, uniform syntax. Furthermore, in keeping with the spirit of Pascal, an attempt has been made to make the facilities straightforward and simple. The design and implementation details are discussed.     

On the realization of extended control structures in FORTRAN

This paper gives a survey of methods used for the realization of extended control structures, FORTRAN is taken as an example language. A proposal is made whose concept is to extend a language dynamically by control structures which are composed from elements of an extendable set of structural components.     

Automatic generation of aggregate operators in ALGOL 68

It is quite often necessary to write several variations of an ALGOL 68 operator to allow the dimensionality of the operands to vary from one variation to another. A system has been written which will automatically generate such variations. The system is a preprocessor written in SNOBOL.     

CScout: A refactoring browser for C

Despite its maturity and popularity, the C programming language still lacks tool support for reliably performing even simple refactoring, browsing, or analysis operations. This is primarily due to identifier scope complications introduced by the C preprocessor. The CScout refactoring browser analyses complete program families by tagging the original identifiers with their precise location and classifying them into equivalence classes orthogonal to the C language’s namespace and scope extents. A web-based user interface provides programmers with an intuitive source code analysis and navigation front-end, while an sql-based back-end allows more complex source code analysis and manipulation. CScout has been successfully applied to many medium and large-sized proprietary and open-source projects identifying thousands of modest refactoring opportunities.     

Porting a global ocean model onto a shared-memory multiprocessor: Observations and guidelines

A three-dimensional global ocean circulation model has been modified to run on the BBN TC2000 multiple instruction stream/multiple data stream (MIMD) parallel computer. Two shared-memory parallel programming models have been used to implement the global ocean model on the TC2000: the TCF (TC2000 Fortran) fork-join model and the PFP (Parallel Fortran Preprocessor) split-join model. The method chosen for the parallelization of this global ocean model on a shared-memory MIMD machine is discussed. The performance of each version of the code has been measured by varying the processor count for a fixed-resolution test case. The statically scheduled PFP version of the code achieves a higher parallel computing efficiency than does the dynamically scheduled TCF version of the code. The observed differences in the performance of the TCF and PFP versions of the code are discussed. The parallel computing performance of the shared-memory implementation of the global ocean model is limited by several factors, most notably load imbalance and network contention. The experience gained while porting this large, real world application onto a shared-memory multiprocessor is also presented to provide insight to the reader who may be contemplating such an undertaking.     

Improving the structure of large Pascal programs

This paper describes an extension to Pascal in the form of an encapsulation mechanism aimed at improving the structure of large Pascal programs. It is based upon the module structure of Modula but extended to include a more detailed specification of module interfaces and to allow the definition of a module body to be deferred. Called Pascal/M, the extended language is implemented via a preprocessor. It has been successfully used in large programming projects and been found to both aid in the application of top-down design methods and to greatly improve the documentation of the final product by breaking up the program text into a hierarchy of short readable modules. The use of Pascal/M is illustrated by a program example and aspects of its design and implementation are discussed.     

面向对象程序设计(C++)中类的定义

本文讲述了在VisualC 6.0环境下,类的定义的三种方法,并且讲述了在类的外部实现类的成员函数时要注意的问题:包括派生类的构造函数中的初始化表,带缺省参数的成员函数、虚拟成员函数等。     

面向PHP应用程序的SQL注入行为检测

层出不穷的SQL注入攻击使Web应用面临威胁。针对PHP应用程序中的SQL注入行为，提出了一种基于污点分析的SQL注入行为检测模型。首先，该模型使用PHP扩展技术在SQL函数执行时获取SQL语句，并记录攻击者所携带的身份信息；基于以上信息生成SQL请求日志，并将该日志作为分析源。然后，基于SQL语法和抽象语法树，实现了污点标记的SQL语法分析过程，并使用污点分析技术，提取语法树中SQL注入行为的多个特征。最后，使用随机森林分类算法实现SQL注入行为的判定。与正则匹配检测技术对比实验结果显示，通过该模型检测SQL注入行为，准确率为96.9%，准确率提高了7.2个百分点。该模型的信息获取模块能以扩展形式加载在任何PHP应用程序中，因此该模型可移植性强，在安全审计和攻击溯源中具有应用价值。     

RATSNO—an experiment in software adaptability

Adaptable programs are one of the benefits of structured programming. The adaptability of a program is the degree to which it can be transformed into another program that performs a similar, but slightly different, function. While it is clear that the aims of structured programming are best satisfied by the use of modern programming languages, a great number of programmers must use languages such as Fortran. To alleviate this situation, a number of preprocessors have been introduced that give Fortran a more structured facade. This paper describes an experiment performed to test the adaptability of programs written in RATFOR, one of these preprocessors. Judging from the results, the use of a good preprocessor can significantly increase the adaptability of Fortran programs.