This ebook is the first authorized digital version of Kernighan and Ritchie's 1988 classic, The C Programming Language (2nd Ed.). One of the best-selling programming books published in the last fifty years, "K&R" has been called everything from the "bible" to "a landmark in computer science" and it has influenced generations of programmers. Available now for all leading ebook platforms, this concise and beautifully written text is a "must-have" reference for every serious programmers digital library.

As modestly described by the authors in the Preface to the First Edition, this "is not an introductory programming manual; it assumes some familiarity with basic programming concepts like variables, assignment statements, loops, and functions. Nonetheless, a novice programmer should be able to read along and pick up the language, although access to a more knowledgeable colleague will help."

The C programming language

Domain-specific languages (DSLs) are languages tailored to a specific application domain. They offer substantial gains in expressiveness and ease of use compared with general-purpose programming languages in their domain of application. DSL development is hard, requiring both domain knowledge and language development expertise. Few people have both. Not surprisingly, the decision to develop a DSL is often postponed indefinitely, if considered at all, and most DSLs never get beyond the application library stage.Although many articles have been written on the development of particular DSLs, there is very limited literature on DSL development methodologies and many questions remain regarding when and how to develop a DSL. To aid the DSL developer, we identify patterns in the decision, analysis, design, and implementation phases of DSL development. Our patterns improve and extend earlier work on DSL design patterns. We also discuss domain analysis tools and language development systems that may help to speed up DSL development. Finally, we present a number of open problems.

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When and how to develop domain-specific languages

Global software development is rapidly becoming the norm for technology companies. Previous qualitative research suggests that distributed development may increase development cycle time for individual work items (modification requests). We use both data from the source code change management system and survey data to model the extent of delay in a distributed software development organization and explore several possible mechanisms for this delay. One key finding is that distributed work items appear to take about two and one-half times as long to complete as similar items where all the work is colocated. The data strongly suggest a mechanism for the delay, i.e., that distributed work items involve more people than comparable same-site work items, and the number of people involved is strongly related to the calendar time to complete a work item. We replicate the analysis of change data in a different organization with a different product and different sites and confirm our main findings. We also report survey results showing differences between same-site and distributed social networks, testing several hypotheses about characteristics of distributed social networks that may be related to delay. We discuss implications of our findings for practices and collaboration technology that have the potential for dramatically speeding distributed software development.

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An empirical study of speed and communication in globally distributed software development

We apply data mining to version histories in order to guide programmers along related changes: "Programmers who changed these functions also changed...." Given a set of existing changes, the mined association rules 1) suggest and predict likely further changes, 2) show up item coupling that is undetectable by program analysis, and 3) can prevent errors due to incomplete changes. After an initial change, our ROSE prototype can correctly predict further locations to be changed; the best predictive power is obtained for changes to existing software. In our evaluation based on the history of eight popular open source projects, ROSE's topmost three suggestions contained a correct location with a likelihood of more than 70 percent.

Mining version histories to guide software changes

We apply data mining to version histories in order to guide programmers along related changes: "Programmers who changed these functions also changed. . . ". Given a set of existing changes, such rules (a) suggest and predict likely further changes, (b) show up item coupling that is indetectable by program analysis, and (c) prevent errors due to incomplete changes. After an initial change, our ROSE prototype can correctly predict 26% of further files to be changed - and 15% of the precise functions or variables. The topmost three suggestions contain a correct location with a likelihood of 64%.

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We report on our experiences of introducing an instant messaging and group chat application into geographically distributed workgroups. We describe a number of issues we encountered, including privacy concerns, individual versus group training, and focusing on teams or individuals. The perception of the tool's utility was a complex issue, depending both on users' views of the importance of informal communication, and their perceptions of the nature of cross-site communication issues. Finally, we conclude with a discussion of critical mass, which is related to the features each user actually uses. More generally, we encountered a dilemma that imposes serious challenges for user-centered design of groupware systems

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Introducing instant messaging and chat in the workplace

A form-based service is one in which the flow of data between service and user is described by a sequence of query/response interactions, or forms. Mawl is a domain-specific language for programming form-based services in a device-independent manner. We focus on Mawl's form abstraction, which is the means for separating service logic from user interface description, and show how this simple abstraction addresses seven issues in service creation, analysis, and maintenance: compile-time guarantees, implementation flexibility, rapid prototyping, testing and validation, support for multiple devices, composition of services, and usage analysis.

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Mawl: a domain-specific language for form-based services

We describe a system for creating, maintaining, and analyzing interactive services that require access from multiple devices. The system augments the infrastructure of the World Wide Web with Mawl, an application-oriented language for specifying form-based services in a device-independent manner, and TelePortal, a software/hardware platform that enables telephone access to Web content via standard interactive voice response (IVR) platforms. Service creators link service logic and presentation with templates written in an extension of the HyperText Markup Language (HTML). HTML is extended with marks for dynamic content (Meta-HTML) and with marks specific to a user interface or access device. Documents to be interpreted by TelePortal are written in the Phone Markup Language (PML). Together, Mawl and TelePortal provide a new way to create integrated services, as well as IVR services. The ability to develop such services in a single environment appears to be unique.

Integrated web and telephone service creation

Software tools can improve the quality and maintainability of software, but are expensive to acquire, deploy and maintain, especially in large organizations. We explore how to quantify the effects of a software tool once it has been deployed in a development environment. We present a simple methodology for tool evaluation that correlates tool usage statistics with estimates of developer effort, as derived from a project's change history (version control system). Our work complements controlled experiments on software tools, which usually take place outside the industrial setting, and tool assessment studies that predict the impact of software tools before deployment. Our analysis is inexpensive, non-intrusive and can be applied to an entire software project in its actual setting. A key part of our analysis is how to control confounding variables such as developer work-style and experience in order accurately to quantify the impact of a tool on developer effort. We demonstrate our method in a case study of a software tool called VE, a version-sensitive editor used in BellLabs. VE aids software developers in coping with the rampant use of preprocessor directives (such as if/ endif) in C source files. Our analysis found that developers were approximately 36% more productive when using VE than when using standard text editors.

Using version control data to evaluate the impact of software tools

Apparatus for visualizing slices of transitive closures of entities having dependence relationships with one another. A preferred embodiment visualizes slices of programs. A display in a computer system includes reduced representations of the files, procedures, and lines making up a program. The user employs a pointing device to interactively select a reduced representation as the slice point and the apparatus computes the slice and changes the color of the reduced representations in the slice. The color of the reduced representation indicates the distance of the entity represented by the reduced representation from the slice point. The display may be rearranged so that files and procedures are ordered by distance from the slice point. Other aspects of the display include scaling the size of the reduced representation of a procedure to indicate the number of lines in the procedure and filling the reduced representation of the procedure according to the number of lines belonging to the slice which are contained in the procedure. A user may select open and closed representations of procedures. The open representation of a procedure contains reduced representations of the lines in the procedure. The apparatus also includes a viewer for viewing the text of lines in the program.

David L. Atkins

Papers

Introducing instant messaging and chat in the workplace

Mawl: a domain-specific language for form-based services

Integrated web and telephone service creation

Using version control data to evaluate the impact of software tools

Apparatus for visualizing program slices