Function Literals and Value Closures Proposal for C23
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By Kumari Priyadarshani 22-04-2020 BBM 3Rd Year Variables in C a Variable Is a Name of the Memory Location. It Is Used to Store Data
By Kumari priyadarshani 22-04-2020 BBM 3rd year Variables in C A variable is a name of the memory location. It is used to store data. Its value can be changed, and it can be reused many times. It is a way to represent memory location through symbol so that it can be easily identified. Let's see the syntax to declare a variable: type variable_list; The example of declaring the variable is given below: int a; float b; char c; Here, a, b, c are variables. The int, float, char are the data types. We can also provide values while declaring the variables as given below: int a=10,b=20;//declaring 2 variable of integer type float f=20.8; char c='A'; Rules for defining variables A variable can have alphabets, digits, and underscore. A variable name can start with the alphabet, and underscore only. It can't start with a digit. No whitespace is allowed within the variable name. A variable name must not be any reserved word or keyword, e.g. int, float, etc. Valid variable names: int a; int _ab; int a30; Invalid variable names: int 2; int a b; int long; Types of Variables in C There are many types of variables in c: local variable global variable static variable automatic variable external variable 1)Local Variable A variable that is declared inside the function or block is called a local variable. It must be declared at the start of the block. void function1(){ int x=10;//local variable } You must have to initialize the local variable before it is used. -
An Empirical Study Into COBOL Type Inferencing*
Science of Computer Programming ELSEVIERI Science of Computer Programming 40 (2001) 189-211 www.elsevier.nl/locate/scico An empirical study into COBOL type inferencing* Arie van Deursen 1, Leon Moonen 1 * CWL P. 0. Box 94079, 1090 GB Amsterdam, Netherlands Accepted 2 February 2001 Abstract In a typical COBOL program, the data division consists of 50% of the lines of code. Automatic type inference can help to understand the large collections of variable declarations contained therein, showing how variables are related based on their actual usage. The most problematic aspect of type inference is pollution, the phenomenon that types become too large, and contain variables that intuitively should not belong to the same type. The aim of the paper is to provide empirical evidence for the hypothesis that the use of subtyping is an effective way for dealing with pollution. The main results include a tool set to carry out type inference experiments, a suite of metrics characterizing type inference outcomes, and the experimental observation that only one instance of pollution occurs in the case study conducted. @ 2001 Elsevier Science B.V. All rights reserved. Keywords: Software maintenance; Static program analysis; Variable usage; Case study 1. Introduction In this paper, we will be concerned with the variables occurring in a COBOL pro gram. The two main parts of a COBOL program are the data division, containing declarations for all variables used, and the procedure division, which contains the state ments performing the program's functionality. Since it is in the procedure division that the actual computations are made, one would expect this division to be larger than the data division. -
XL C/C++: Language Reference About This Document
IBM XL C/C++ for Linux, V16.1.1 IBM Language Reference Version 16.1.1 SC27-8045-01 IBM XL C/C++ for Linux, V16.1.1 IBM Language Reference Version 16.1.1 SC27-8045-01 Note Before using this information and the product it supports, read the information in “Notices” on page 63. First edition This edition applies to IBM XL C/C++ for Linux, V16.1.1 (Program 5765-J13, 5725-C73) and to all subsequent releases and modifications until otherwise indicated in new editions. Make sure you are using the correct edition for the level of the product. © Copyright IBM Corporation 1998, 2018. US Government Users Restricted Rights – Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp. Contents About this document ......... v Chapter 4. IBM extension features ... 11 Who should read this document........ v IBM extension features for both C and C++.... 11 How to use this document.......... v General IBM extensions ......... 11 How this document is organized ....... v Extensions for GNU C compatibility ..... 15 Conventions .............. v Extensions for vector processing support ... 47 Related information ........... viii IBM extension features for C only ....... 56 Available help information ........ ix Extensions for GNU C compatibility ..... 56 Standards and specifications ........ x Extensions for vector processing support ... 58 Technical support ............ xi IBM extension features for C++ only ...... 59 How to send your comments ........ xi Extensions for C99 compatibility ...... 59 Extensions for C11 compatibility ...... 59 Chapter 1. Standards and specifications 1 Extensions for GNU C++ compatibility .... 60 Chapter 2. Language levels and Notices .............. 63 language extensions ......... 3 Trademarks ............. -
Assignment 6: Subtyping and Bidirectional Typing
Assignment 6: Subtyping and Bidirectional Typing 15-312: Foundations of Programming Languages Joshua Dunfield ([email protected]) Out: Thursday, October 24, 2002 Due: Thursday, November 7 (11:59:59 pm) 100 points total + (up to) 20 points extra credit 1 Introduction In this assignment, you will implement a bidirectional typechecker for MinML with , , +, 1, 0, , , and subtyping with base types int and float. ! ∗ 8 9 Note: In the .sml files, most changes from Assignment 4 are indicated like this: (* new asst6 code: *) ... (* end asst6 code *) 2 New in this assignment Some things have become obsolete (and have either been removed or left • in a semi-supported state). Exceptions and continuations are no longer “officially” supported. One can now (and sometimes must!) write type annotations e : τ. The • abstract syntax constructor is called Anno. The lexer supports shell-style comments in .mml source files: any line • beginning with # is ignored. There are now two valid syntaxes for functions, the old syntax fun f (x:t1):t2 is e end • and a new syntax fun f(x) is e end. Note the lack of type anno- tations. The definition of the abstract syntax constructor Fun has been changed; its arguments are now just bindings for f and x and the body. It no longer takes two types. 1 The old syntax fun f(x:t1):t2 is e end is now just syntactic sugar, transformed by the parser into fun f(x) is e end : t1 -> t2. There are floating point numbers, written as in SML. There is a new set of • arithmetic operators +., -., *., ˜. -
(901133) Instructor: Eng
home Al-Albayt University Computer Science Department C++ Programming 1 (901133) Instructor: Eng. Rami Jaradat [email protected] 1 home Subjects 1. Introduction to C++ Programming 2. Control Structures 3. Functions 4. Arrays 5. Pointers 6. Strings 2 home 1 - Introduction to C++ Programming 3 home What is computer? • Computers are programmable devices capable of performing computations and making logical decisions. • Computers can store, retrieve, and process data according to a list of instructions • Hardware is the physical part of the compute: keyboard, screen, mouse, disks, memory, and processing units • Software is a collection of computer programs, procedures and documentation that perform some tasks on a computer system 4 home Computer Logical Units • Input unit – obtains information (data) from input devices • Output unit – outputs information to output device or to control other devices. • Memory unit – Rapid access, low capacity, stores information • Secondary storage unit – cheap, long-term, high-capacity storage, stores inactive programs • Arithmetic and logic unit (ALU) – performs arithmetic calculations and logic decisions • Central processing unit (CPU): – supervises and coordinates the other sections of the computer 5 home Computer language • Machine languages: machine dependent, it consists of strings of numbers giving machine specific instructions: +1300042774 +1400593419 +1200274027 • Assembly languages: English-like abbreviations representing elementary operations, assemblers convert assembly language to machine -
Language Reference
Enterprise PL/I for z/OS Version 5 Release 3 Language Reference IBM SC27-8940-02 Note Before using this information and the product it supports, be sure to read the general information under “Notices” on page 613. Third Edition (September 2019) This edition applies to Enterprise PL/I for z/OS Version 5 Release 3 (5655-PL5), and IBM Developer for z/OS PL/I for Windows (former Rational Developer for System z PL/I for Windows), Version 9.1, and to any subsequent releases of any of these products until otherwise indicated in new editions or technical newsletters. Make sure you are using the correct edition for the level of the product. Order publications through your IBM® representative or the IBM branch office serving your locality. Publications are not stocked at the address below. A form for readers' comments is provided at the back of this publication. If the form has been removed, address your comments to: IBM Corporation, Department H150/090 555 Bailey Ave. San Jose, CA, 95141-1099 United States of America When you send information to IBM, you grant IBM a nonexclusive right to use or distribute the information in any way it believes appropriate without incurring any obligation to you. Because IBM Enterprise PL/I for z/OS supports the continuous delivery (CD) model and publications are updated to document the features delivered under the CD model, it is a good idea to check for updates once every three months. © Copyright International Business Machines Corporation 1999, 2019. US Government Users Restricted Rights – Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp. -
Explicitly Implicifying Explicit Constructors
Explicitly Implicifying explicit Constructors Document number: P1163R0 Date: 2018-08-31 Project: Programming Language C++, Library Working Group Reply-to: Nevin “☺” Liber, [email protected] or [email protected] Table of Contents Revision History ................................................................................................................ 3 P11630R0 .................................................................................................................................... 3 Introduction ....................................................................................................................... 4 Motivation and Scope ....................................................................................................... 5 Impact On the Standard ................................................................................................... 6 Policy .................................................................................................................................. 7 Design Decisions ................................................................................................................ 8 Technical Specifications ................................................................................................... 9 [template.bitset]........................................................................................................................ 10 [bitset.cons] .............................................................................................................................. -
The Cool Reference Manual∗
The Cool Reference Manual∗ Contents 1 Introduction 3 2 Getting Started 3 3 Classes 4 3.1 Features . 4 3.2 Inheritance . 5 4 Types 6 4.1 SELF TYPE ........................................... 6 4.2 Type Checking . 7 5 Attributes 8 5.1 Void................................................ 8 6 Methods 8 7 Expressions 9 7.1 Constants . 9 7.2 Identifiers . 9 7.3 Assignment . 9 7.4 Dispatch . 10 7.5 Conditionals . 10 7.6 Loops . 11 7.7 Blocks . 11 7.8 Let . 11 7.9 Case . 12 7.10 New . 12 7.11 Isvoid . 12 7.12 Arithmetic and Comparison Operations . 13 ∗Copyright c 1995-2000 by Alex Aiken. All rights reserved. 1 8 Basic Classes 13 8.1 Object . 13 8.2 IO ................................................. 13 8.3 Int................................................. 14 8.4 String . 14 8.5 Bool . 14 9 Main Class 14 10 Lexical Structure 14 10.1 Integers, Identifiers, and Special Notation . 15 10.2 Strings . 15 10.3 Comments . 15 10.4 Keywords . 15 10.5 White Space . 15 11 Cool Syntax 17 11.1 Precedence . 17 12 Type Rules 17 12.1 Type Environments . 17 12.2 Type Checking Rules . 18 13 Operational Semantics 22 13.1 Environment and the Store . 22 13.2 Syntax for Cool Objects . 24 13.3 Class definitions . 24 13.4 Operational Rules . 25 14 Acknowledgements 30 2 1 Introduction This manual describes the programming language Cool: the Classroom Object-Oriented Language. Cool is a small language that can be implemented with reasonable effort in a one semester course. Still, Cool retains many of the features of modern programming languages including objects, static typing, and automatic memory management. -
Generic Immutability and Nullity Types for an Imperative Object-Oriented Programming Language with flexible Initialization
Generic Immutability and Nullity Types for an imperative object-oriented programming language with flexible initialization James Elford June 21, 2012 Abstract We present a type system for parametric object mutability and ref- erence nullity in an imperative object oriented language. We present a simple but powerful system for generic nullity constraints, and build on previous work to provide safe initialization of objects which is not bound to constructors. The system is expressive enough to handle initialization of cyclic immutable data structures, and to enforce their cyclic nature through the type system. We provide the crucial parts of soundness ar- guments (though the full proof is not yet complete). Our arguments are novel, in that they do not require auxiliary runtime constructs (ghost state) in order to express or demonstrate our desired properties. 2 Contents 1 Introduction 4 1.1 In this document . .5 2 Background 6 2.1 Parametric Types . .6 2.1.1 Static Polymorphism through Templates . .7 2.1.2 Static Polymorphism through Generic Types . 12 2.2 Immutability . 18 2.2.1 Immutability in C++ .................... 19 2.2.2 Immutability in Java and C# ............... 21 2.2.3 An extension to Java's immutability model . 21 2.2.4 Parametric Immutability Constraints . 24 2.3 IGJ: Immutability Generic Java .................. 25 2.4 Nullity . 27 2.5 Areas of commonality . 30 3 Goals 32 4 Existing systems in more detail 34 4.1 The initialization problem . 34 4.2 What do we require from initialization? . 35 4.3 Approaches to initialization . 37 4.4 Delay Types and initialization using stack-local regions . -
Fundamentals of Programming Session 12
Fundamentals of Programming Session 12 Instructor: Maryam Asadi Email: [email protected] 1 Fall 2018 These slides have been created using Deitel’s slides Sharif University of Technology Outlines Random Number Generation … Storage Classes Scope Rules 2 Random Number Generation … The values produced directly by rand are always in the range: 0 rand() RAND_MAX As you know, the following statement simulates rolling a six- sided die: face = 1 + rand() % 6; This statement always assigns an integer value (at random) to the variable face in the range 1 face 6. The width of this range (i.e., the number of consecutive integers in the range) is 6 and the starting number in the range is 1. 3 Random Number Generation … Referring to the preceding statement, we see that the width of the range is determined by the number used to scale rand with the remainder operator (i.e., 6), and the starting number of the range is equal to the number (i.e., 1) that is added to rand % 6. We can generalize this result as follows n = a + rand() % b; where a is the shifting value (which is equal to the first number in the desired range of consecutive integers) and b is the scaling factor (which is equal to the width of the desired range of consecutive integers). 4 Random Number Generation … 5 Random Number Generation … 6 Random Number Generation … Notice that a different sequence of random numbers is obtained each time the program is run, provided that a different seed is supplied. To randomize without entering a seed each time, use a statement like srand( time( NULL ) ); This causes the computer to read its clock to obtain the value for the seed automatically. -
C DEFINES and C++ TEMPLATES Professor Ken Birman
Professor Ken Birman C DEFINES AND C++ TEMPLATES CS4414 Lecture 10 CORNELL CS4414 - FALL 2020. 1 COMPILE TIME “COMPUTING” In lecture 9 we learned about const, constexpr and saw that C++ really depends heavily on these Ken’s solution to homework 2 runs about 10% faster with extensive use of these annotations Constexpr underlies the “auto” keyword and can sometimes eliminate entire functions by precomputing their results at compile time. Parallel C++ code would look ugly without normal code structuring. Const and constexpr allow the compiler to see “beyond” that and recognize parallelizable code paths. CORNELL CS4414 - FALL 2020. 2 … BUT HOW FAR CAN WE TAKE THIS IDEA? Today we will look at the concept of programming the compiler using the templating layer of C++ We will see that it is a powerful tool! There are also programmable aspects of Linux, and of the modern hardware we use. By controlling the whole system, we gain speed and predictability while writing elegant, clean code. CORNELL CS4414 - FALL 2020. 3 IDEA MAP FOR TODAY History of generics: #define in C Templates are easy to create, if you stick to basics The big benefit compared to Java is that a template We have seen a number of parameterized is a compile-time construct, whereas in Java a generic types in C++, like std::vector and std::map is a run-time construct. The template language is Turing-complete, but computes These are examples of “templates”. only on types, not data from the program (even when They are like generics in Java constants are provided). -
Class Notes on Type Inference 2018 Edition Chuck Liang Hofstra University Computer Science
Class Notes on Type Inference 2018 edition Chuck Liang Hofstra University Computer Science Background and Introduction Many modern programming languages that are designed for applications programming im- pose typing disciplines on the construction of programs. In constrast to untyped languages such as Scheme/Perl/Python/JS, etc, and weakly typed languages such as C, a strongly typed language (C#/Java, Ada, F#, etc ...) place constraints on how programs can be written. A type system ensures that programs observe logical structure. The origins of type theory stretches back to the early twentieth century in the work of Bertrand Russell and Alfred N. Whitehead and their \Principia Mathematica." They observed that our language, if not restrained, can lead to unsolvable paradoxes. Specifically, let's say a mathematician defined S to be the set of all sets that do not contain themselves. That is: S = fall A : A 62 Ag Then it is valid to ask the question does S contain itself (S 2 S?). If the answer is yes, then by definition of S, S is one of the 'A's, and thus S 62 S. But if S 62 S, then S is one of those sets that do not contain themselves, and so it must be that S 2 S! This observation is known as Russell's Paradox. In order to avoid this paradox, the language of mathematics (or any language for that matter) must be constrained so that the set S cannot be defined. This is one of many discoveries that resulted from the careful study of language, logic and meaning that formed the foundation of twentieth century analytical philosophy and abstract mathematics, and also that of computer science.