# 9/21/17. Outline. Expression Evaluation and Control Flow. Arithmetic Expressions. Operators. Operators. Notation & Placement

Size: px
Start display at page:

Download "9/21/17. Outline. Expression Evaluation and Control Flow. Arithmetic Expressions. Operators. Operators. Notation & Placement"

Transcription

1 Outline Expression Evaluation and Control Flow In Text: Chapter 6 Notation Operator evaluation order Operand evaluation order Overloaded operators Type conversions Short-circuit evaluation of conditions Control structures N. Meng, S. Arthur 2 Arithmetic Expressions Design issues for arithmetic expressions Notation form? What are the operator precedence rules? What are the operator associativity rules? What is the order of operand evaluation? Are there restrictions on operand evaluation side effects? Does the language allow user-defined operator overloading? Operators A unary operator has one operand A binary operator has two operands A ternary operator has three operands Functions can be viewed as unary operators with an operand of a simple list N. Meng, S. Arthur 3 N. Meng, S. Arthur 4 Operators Argument lists (or parameter lists) treat separators (comma, space) as stacking or append operators A keyword in a language statement can be viewed as functions in which the remainder of the statement is the operand Notation & Placement Prefix op a b op(a,b) (op a b) Infix a op b Postfix a b op N. Meng, S. Arthur 5 N. Meng, S. Arthur 6 1

2 Notation & Placement Most imperative languages use infix notation for binary and prefix for unary operators Lisp: prefix (op a b) Operator Evaluation Order Precedence Associativity Parentheses N. Meng, S. Arthur 7 N. Meng, S. Arthur 8 Operator Precedence Define the order in which adjacent operators of different precedence levels are evaluated Parenthetical groups (...) Exponentiation ** Mult & Div *, / Add & Sub +, - Assignment := Where to put the parentheses? E.g., A * B + C ** D / E - F Only Fortran, Ruby, Visual Basic, and Ada have the exponentiation operator. In all four, exponentiation operator has higher precedence than unary operators Where to place the parentheses in A**B? N. Meng, S. Arthur 9 N. Meng, S. Arthur 10 Operator Associativity The precedence of the arithmetic operators of Ruby and the C-based languages (e.g., C, C++, Java, Python) Ruby C-Based Languages Highest ** postfix ++, -- unary +, - prefix ++, --, unary +, - *, /, % *, /, % Lowest binary +, - binary +, - Define the order in which adjacent operators with the same precedence level are evaluated: Left associative *, /, +, - Right associative ** (exponentiation) Where to put the parentheses? E.g., B ** C ** D - E + F * G / H N. Meng, S. Arthur 11 N. Meng, S. Arthur 12 2

3 Operator Associativity EFFECTIVELY Most programming languages evaluate expressions from left to right LISP uses parentheses to enforce evaluation order APL is strictly RIGHT to LEFT, taking note only of parenthetical groups Operator Associativity Associativity For some operators, the evaluation order does not matter, i.e., (A + B) + C = A + (B + C) However, in a computer when floatingpoint numbers are represented approximately, the mathematical associativity does not always hold E.g., A = 200, B = Float.MIN_VALUE, C = -10 N. Meng, S. Arthur 13 N. Meng, S. Arthur 14 Parentheses Programmers can alter the precedence and associativity rules by placing parentheses in expressions A parenthesized part of an expression has precedence over its adjacent peers without parentheses Parentheses Advantages Allow programmers to specify any desired order of evaluation Do not require author or reader of programs to remember any precedence or association rules Disadvantages Can make writing expressions more tedious May seriously compromise code readability N. Meng, S. Arthur 15 N. Meng, S. Arthur 16 Expression Conversion Although we need parentheses in infix expressions, we don t need parentheses in prefix and postfix expressions The operators are no longer ambiguous with respect to the operands that they work on in prefix and postfix expressions Infix Expression Prefix Expression Pos.ix Expression A+B + A B A B + A+B*C?? (A+B)*C?? N. Meng, S. Arthur 17 N. Meng, S. Arthur 18 3

4 A Motivating Example What is the value of the following expression? * How do you automate the calculation of a postfix expression? Assuming operators include: Highest * / Lowest binary + - Input: a string of a postfix expression Output: a value Algorithm? N. Meng, S. Arthur 19 N. Meng, S. Arthur 20 Project 1 Create an evaluator for logical expressions written in postfix notation Assuming operators include: Highest not! RIGHT associative and & not equal /, equal = Lowest or LEFT associative Operand Evaluation Order If none of the operands of an operator has side effects, then the operand evaluation order does not matter What are side effects? Referential transparency and side effects N. Meng, S. Arthur 21 N. Meng, S. Arthur 22 Side Effects Often discussed in the context of functions A side effect is some permanent state change caused by execution of functions The subsequent computation is influenced other than by the return value for use j = i++ a = 10, b = a + fun(&a) (assume the function can change its parameter value) N. Meng, S. Arthur 23 Side Effects Many imperative languages distinguish between expressions, which always produce values, and may or may not have side effects, and statements, which are executed solely for their side effects, and return no useful value Imperative programming is sometimes called computing via side effects N. Meng, S. Arthur 24 4

5 Side Effects Pure functional languages have no side effects The value of an expression depends only on the referencing environment in which the expression is evaluated, not the time at which the evaluation occurs If an expression yields a certain value at one point in time, it is guaranteed to yield the same value at any point in time How to avoid side effects? Design the language to disallow functional side effects No pass-by-reference parameters in functions Disallow global variable access in functions Concerns Programmers need the flexibility to return more than one value from a function Passing parameters is inefficient compared with accessing global variables N. Meng, S. Arthur 25 N. Meng, S. Arthur 26 How to avoid side effects? Design the language with a strictly fixed evaluation order between operands Concerns Disallow some optimizations which involve reordering operand evaluations Referential Transparency and Side Effects A program has the property of referential transparency if any two expressions having the same value can be substituted for one another E.g., result1 = (fun(a) + b) / (fun(a) c); ó temp = fun(a); result2 = (temp + b) / (temp - c), given that the function fun has no side effect N. Meng, S. Arthur 27 N. Meng, S. Arthur 28 Key points of referentially transparent programs Semantics is much easier to understand Being referentially transparent makes a function equivalent to a mathematical function Programs written in pure functional languages are referentially transparent The value of a referentially transparent function depends on its parameters, and possibly one or more global constants N. Meng, S. Arthur 29 Overloaded Operators The multiple use of an operator is called operator overloading E.g., + is used to specify integer addition, floating-point addition, and string catenation Do not use the same symbol for two completely unrelated operations, because that can decrease readability In C, & can represent a bitwise AND operator, and an address-of operator N. Meng, S. Arthur 30 5

6 Type Conversion Narrowing conversion To convert a value to a type that cannot store all values of the original type E.g., double->float, float->int Widening conversion To convert a value to a type that can include all values belong to the original type E.g., int->float, float->double N. Meng, S. Arthur 31 Narrowing Conversion vs. Widening Conversion Narrowing conversion are not always safe The magnitude of the converted value can be changed E.g., float->int with 1.3E25, the converted value is distantly related to the original one Widening conversion is always safe However, some precision may be lost E.g., int->float, integers have at least 9 decimal digits of precision, while floats have 7 decimal digits of precision 32 Implicit Type Conversion A coercion is an implicit type conversion Arithmetic expressions with operators that can have differently typed operands are called mixed-mode expressions Languages allowing such expressions must define implicit operand type conversions Implicit Type Conversion var x, y: integer; z: real;... y := x * z; /* x is automancally converted to real */ Implicit type conversion can be achieved by narrowing or widening one or more operators It is better to widen when possible E.g., x = 3, z = 5.9, what is y s value if x is widened? How about z narrowed? N. Meng, S. Arthur 33 N. Meng, S. Arthur 34 Key Points of Implicit Coercions They decrease the type error detection ability of compilers Did you really mean to use mixed-mode expressions? In most languages, all numeric types are coerced in expressions, using widening conversions Explicit Type Conversion Also called casts Ada example FLOAT(INDEX)-- INDEX is an INTEGER C example: (int) speed /* speed is a float */ N. Meng, S. Arthur 35 N. Meng, S. Arthur 36 6

7 Short-Circuit Evaluation A short-circuit evaluation of an expression is one in which the result is determined without evaluating all of the operands and/or operators Consider (a < b) && (b < c): If a >= b, there is no point evaluating b < c because (a < b) && (b < c) is automatically false (x && y) if x then y else false (x y) if x then true else y Short-Circuit Evaluation Short-circuit evaluation may lead to unexpected side effects and cause error E.g., (a > b) ((b++) / 3) C, C++, and Java: Use short-circuit evaluation for Boolean operations (&& and ) Also provide bitwise operators that are not short circuit (& and ) N. Meng, S. Arthur 37 N. Meng, S. Arthur 38 Short-Circuit Evaluation Ada: programmers can specify either Non-SC eval SC eval (x or y) ( x or else y ) (x and y) ( x and then y ) Control Structures Selection Iteration Iterators Recursion Concurrency & non-determinism Guarded commands N. Meng, S. Arthur 39 N. Meng, S. Arthur 40 Iteration Based on Data Structures A data-based iteration statement uses a user-defined data structure and a userdefined function to go through the structure s elements The function is called an iterator The iterator is invoked at the beginning of each iteration Each time it is invoked, an element from the data structure is returned Elements are returned in a particular order A Java Implementation for Iterator N. Meng, S. Arthur

8 Guarded Commands New and quite different forms of selection and loop structures were suggested by Dijkstra (1975) We cover guarded commands because they are the basis for two linguistic mechanisms developed later for concurrent programming in two languages: CSP and Ada Motivations of Guarded Commands To support a program design methodology that ensures correctness during development rather than relying on verification or testing of completed programs afterwards Also useful for concurrency Increased clarity in reasoning N. Meng, S. Arthur 43 N. Meng, S. Arthur 44 Guarded Commands Two guarded forms Selection (guarded if) Iteration (guarded do) N. Meng, S. Arthur 45 Guarded Selection if <boolean> -> <statement> [] <boolean> -> <statement>... [] <boolean> -> <statement> fi Sementics When this construct is reached Evaluate all boolean expressions If more than one is true, choose one nondeterministically If none is true, it is a runtime error Idea: Forces one to consider all possibilities N. Meng, S. Arthur 46 An Example if i = 0 -> sum := sum + i [] i > j -> sum := sum + j [] j > i -> sum := sum + i fi If i = 0 and j > i, the construct chooses nondeterministically between the first and the third assignment statements If i == j and i 0, none of the conditions is true and a runtime error occurs N. Meng, S. Arthur 47 Guarded Selection The construction can be an elegant way to state that the order of execution, in some cases, is irrelevant if x >= y -> max := x [] y >= x -> max := y fi E.g., if x == y, it does not matter which we assign to max This is a form of abstraction provided by the nondeterministic semantics N. Meng, S. Arthur 48 8

9 Guarded Iteration Semantics: For each iteration do <boolean> -> <statement> [] <boolean> -> <statement>... [] <boolean> -> <statement> od Evaluate all boolean expressions If more than one is true, choose one nondeterministically, and then start loop again If none is true, exit the loop Idea: if the order of evaluation is not important, the program should not specify one N. Meng, S. Arthur 49 An Example do q1 > q2 -> temp := q1; q1 := q2; q2 := temp; [] q2 > q3 -> temp := q2; q2 := q3; q3 := temp; [] q3 > q4 -> temp := q3; q3 := q4; q4 := temp; od Given four integer variables: q1, q2, q3, and q4, rearrange the values so that q1 q2 q3 q4 Without guarded iteration, one solution is to put the values into an array, sort the array, and then assigns the value back to the four variables N. Meng, S. Arthur 50 An Example While the solution with guarded iteration is not difficult, it requires a good deal of code There is considerably increased complexity in the implementation of the guarded commands over their conventional deterministic counterparts N. Meng, S. Arthur 51 9

### Expression Evaluation and Control Flow. Outline

Expression Evaluation and Control Flow In Text: Chapter 6 Outline Notation Operator Evaluation Order Operand Evaluation Order Overloaded operators Type conversions Short-circuit evaluation of conditions

### Software II: Principles of Programming Languages. Why Expressions?

Software II: Principles of Programming Languages Lecture 7 Expressions and Assignment Statements Why Expressions? Expressions are the fundamental means of specifying computations in a programming language

### Chapter 7. Expressions and Assignment Statements ISBN

Chapter 7 Expressions and Assignment Statements ISBN 0-321-49362-1 Chapter 7 Topics Introduction Arithmetic Expressions Overloaded Operators Type Conversions Relational and Boolean Expressions Short-Circuit

### Chapter 7. Expressions and Assignment Statements

Chapter 7 Expressions and Assignment Statements Chapter 7 Topics Introduction Arithmetic Expressions Overloaded Operators Type Conversions Relational and Boolean Expressions Short-Circuit Evaluation Assignment

### Expressions & Assignment Statements

Expressions & Assignment Statements 1 Topics Introduction Arithmetic Expressions Overloaded Operators Type Conversions Relational and Boolean Expressions Short-Circuit Evaluation Assignment Statements

### Chapter 7. Expressions and Assignment Statements ISBN

Chapter 7 Expressions and Assignment Statements ISBN 0-321-33025-0 Chapter 7 Topics Introduction Arithmetic Expressions Overloaded Operators Type Conversions Relational and Boolean Expressions Short-Circuit

### Chapter 7. Expressions and Assignment Statements (updated edition 11) ISBN

Chapter 7 Expressions and Assignment Statements (updated edition 11) ISBN 0-321-49362-1 Chapter 7 Topics Introduction Arithmetic Expressions Overloaded Operators Type Conversions Relational and Boolean

### CSE 452: Programming Languages. Outline of Today s Lecture. Expressions. Expressions and Control Flow

CSE 452: Programming Languages Expressions and Control Flow Outline of Today s Lecture Expressions and Assignment Statements Arithmetic Expressions Overloaded Operators Type Conversions Relational and

### Expressions and Assignment Statements

Expressions and Assignment Statements Introduction Expressions are the fundamental means of specifying computations in a programming language To understand expression evaluation, need to be familiar with

### Expressions and Assignment

Expressions and Assignment COS 301: Programming Languages Outline Other assignment mechanisms Introduction Expressions: fundamental means of specifying computations Imperative languages: usually RHS of

### Chapter 7. Expressions and Assignment Statements

Chapter 7 Expressions and Assignment Statements Chapter 7 Topics Introduction Arithmetic Expressions Overloaded Operators Type Conversions Relational and Boolean Expressions Short-Circuit Evaluation Assignment

### Chapter 7 Expressions and Assignment statements

Chapter 7 Expressions and Assignment statements 1 7.1 Introduction Expressions are the fundamental means of specifying computations in a programming language Semantics of expressions are discussed in this

### LECTURE 17. Expressions and Assignment

LECTURE 17 Expressions and Assignment EXPRESSION SYNTAX An expression consists of An atomic object, e.g. number or variable. An operator (or function) applied to a collection of operands (or arguments)

### Programming Languages Third Edition. Chapter 9 Control I Expressions and Statements

Programming Languages Third Edition Chapter 9 Control I Expressions and Statements Objectives Understand expressions Understand conditional statements and guards Understand loops and variation on WHILE

### G Programming Languages - Fall 2012

G22.2110-003 Programming Languages - Fall 2012 Lecture 3 Thomas Wies New York University Review Last week Names and Bindings Lifetimes and Allocation Garbage Collection Scope Outline Control Flow Sequencing

### Chapter7 Expression and Assignment Statement. Introduction

Chapter7 Expression and Assignment Statement Arithmetic Expressions Overloaded Operators Boolean Expressions Short-Circuit Evaluation Assignment Statements Mixed-Mode Assignment Introduction Fundamental

### Operators and Expressions

Operators and Expressions Conversions. Widening and Narrowing Primitive Conversions Widening and Narrowing Reference Conversions Conversions up the type hierarchy are called widening reference conversions

### Chapter 8. Statement-Level Control Structures ISBN

Chapter 8 Statement-Level Control Structures ISBN 0-321-49362-1 Chapter 8 Topics Introduction Selection Statements Iterative Statements Unconditional Branching Guarded Commands Conclusions Copyright 2012

### Concepts of Programming Languages

Concepts of Programming Languages COMP322 Fall 2012/2013 1-1 Textbook ISBN 0-321-49362-1 Chapter 1 Preliminaries ISBN 0-321-49362-1 Chapter 1 Topics Reasons for Studying Concepts of Programming Languages

### Chapter 8. Statement-Level Control Structures

Chapter 8 Statement-Level Control Structures Chapter 8 Topics Introduction Selection Statements Iterative Statements Unconditional Branching Guarded Commands Conclusions Copyright 2009 Addison-Wesley.

### Chapter 8. Statement-Level Control Structures

Chapter 8 Statement-Level Control Structures Chapter 8 Topics Introduction Selection Statements Iterative Statements Unconditional Branching Guarded Commands Conclusions 1-2 Levels of Control Flow Within

### The PCAT Programming Language Reference Manual

The PCAT Programming Language Reference Manual Andrew Tolmach and Jingke Li Dept. of Computer Science Portland State University September 27, 1995 (revised October 15, 2002) 1 Introduction The PCAT language

### Chapter 3: Operators, Expressions and Type Conversion

101 Chapter 3 Operators, Expressions and Type Conversion Chapter 3: Operators, Expressions and Type Conversion Objectives To use basic arithmetic operators. To use increment and decrement operators. To

### Java enum, casts, and others (Select portions of Chapters 4 & 5)

Enum or enumerates types Java enum, casts, and others (Select portions of Chapters 4 & 5) Sharma Chakravarthy Information Technology Laboratory (IT Lab) Computer Science and Engineering Department The

### Iterative Statements. Iterative Statements: Examples. Counter-Controlled Loops. ICOM 4036 Programming Languages Statement-Level Control Structure

ICOM 4036 Programming Languages Statement-Level Control Structure Selection Statement Iterative Statements Unconditional Branching Guarded Commands This lecture covers review questions 8-16 This lecture

### Chapter 7 Control I Expressions and Statements

Chapter 7 Control I Expressions and Statements Expressions Conditional Statements and Guards Loops and Variation on WHILE The GOTO Controversy Exception Handling Values and Effects Important Concepts in

### 9/7/17. Outline. Name, Scope and Binding. Names. Introduction. Names (continued) Names (continued) In Text: Chapter 5

Outline Name, Scope and Binding In Text: Chapter 5 Names Variable Binding Type bindings, type conversion Storage bindings and lifetime Scope Lifetime vs. Scope Referencing Environments N. Meng, S. Arthur

### The SPL Programming Language Reference Manual

The SPL Programming Language Reference Manual Leonidas Fegaras University of Texas at Arlington Arlington, TX 76019 fegaras@cse.uta.edu February 27, 2018 1 Introduction The SPL language is a Small Programming

### Review of the C Programming Language

Review of the C Programming Language Prof. James L. Frankel Harvard University Version of 11:55 AM 22-Apr-2018 Copyright 2018, 2016, 2015 James L. Frankel. All rights reserved. Reference Manual for the

Lecture Set 4: More About Methods and More About Operators Methods Definitions Invocations More arithmetic operators Operator Side effects Operator Precedence Short-circuiting main method public static

Lecture Set 4: More About Methods and More About Operators Methods Definitions Invocations More arithmetic operators Operator Side effects Operator Precedence Short-circuiting main method public static

### Chapter 6 Control Flow. June 9, 2015

Chapter 6 Control Flow June 9, 2015 Expression evaluation It s common in programming languages to use the idea of an expression, which might be a simple object function invocation over some number of arguments

### ECE 122 Engineering Problem Solving with Java

ECE 122 Engineering Problem Solving with Java Lecture 3 Expression Evaluation and Program Interaction Outline Problem: How do I input data and use it in complicated expressions Creating complicated expressions

### Operators and Expressions in C & C++ Mahesh Jangid Assistant Professor Manipal University, Jaipur

Operators and Expressions in C & C++ Mahesh Jangid Assistant Professor Manipal University, Jaipur Operators and Expressions 8/24/2012 Dept of CS&E 2 Arithmetic operators Relational operators Logical operators

### Java Primer 1: Types, Classes and Operators

Java Primer 1 3/18/14 Presentation for use with the textbook Data Structures and Algorithms in Java, 6th edition, by M. T. Goodrich, R. Tamassia, and M. H. Goldwasser, Wiley, 2014 Java Primer 1: Types,

### Lecture 13: Expression Evaluation

The University of North Carolina at Chapel Hill Spring 2002 Lecture 13: Expression Evaluation Feb 8 1 Control Flow Control flow refers to the order in which a program executes This is fundamental in the

### 1 Lexical Considerations

Massachusetts Institute of Technology Department of Electrical Engineering and Computer Science 6.035, Spring 2013 Handout Decaf Language Thursday, Feb 7 The project for the course is to write a compiler

### Lecture 1. Types, Expressions, & Variables

Lecture 1 Types, Expressions, & Variables About Your Instructor Director: GDIAC Game Design Initiative at Cornell Teach game design (and CS 1110 in fall) 8/29/13 Overview, Types & Expressions 2 Helping

### Lecture 2: Variables & Assignments

http://www.cs.cornell.edu/courses/cs1110/2018sp Lecture 2: Variables & Assignments (Sections 2.1-2.3,2.5) CS 1110 Introduction to Computing Using Python [E. Andersen, A. Bracy, D. Gries, L. Lee, S. Marschner,

### There are four numeric types: 1. Integers, represented as a 32 bit (or longer) quantity. Digits sequences (possibly) signed are integer literals:

Numeric Types There are four numeric types: 1. Integers, represented as a 32 bit (or longer) quantity. Digits sequences (possibly) signed are integer literals: 1-123 +456 2. Long integers, of unlimited

### Primitive Data Types: Intro

Primitive Data Types: Intro Primitive data types represent single values and are built into a language Java primitive numeric data types: 1. Integral types (a) byte (b) int (c) short (d) long 2. Real types

### Unit 3. Operators. School of Science and Technology INTRODUCTION

INTRODUCTION Operators Unit 3 In the previous units (unit 1 and 2) you have learned about the basics of computer programming, different data types, constants, keywords and basic structure of a C program.

### Language Basics. /* The NUMBER GAME - User tries to guess a number between 1 and 10 */ /* Generate a random number between 1 and 10 */

Overview Language Basics This chapter describes the basic elements of Rexx. It discusses the simple components that make up the language. These include script structure, elements of the language, operators,

### Operators and Expressions:

Operators and Expressions: Operators and expression using numeric and relational operators, mixed operands, type conversion, logical operators, bit operations, assignment operator, operator precedence

### Operators. Java operators are classified into three categories:

Operators Operators are symbols that perform arithmetic and logical operations on operands and provide a meaningful result. Operands are data values (variables or constants) which are involved in operations.

### Module 2 - Part 2 DATA TYPES AND EXPRESSIONS 1/15/19 CSE 1321 MODULE 2 1

Module 2 - Part 2 DATA TYPES AND EXPRESSIONS 1/15/19 CSE 1321 MODULE 2 1 Topics 1. Expressions 2. Operator precedence 3. Shorthand operators 4. Data/Type Conversion 1/15/19 CSE 1321 MODULE 2 2 Expressions

### Declaration and Memory

Declaration and Memory With the declaration int width; the compiler will set aside a 4-byte (32-bit) block of memory (see right) The compiler has a symbol table, which will have an entry such as Identifier

### Programming Languages Third Edition. Chapter 7 Basic Semantics

Programming Languages Third Edition Chapter 7 Basic Semantics Objectives Understand attributes, binding, and semantic functions Understand declarations, blocks, and scope Learn how to construct a symbol

### CPS 506 Comparative Programming Languages. Programming Language Paradigm

CPS 506 Comparative Programming Languages Functional Programming Language Paradigm Topics Introduction Mathematical Functions Fundamentals of Functional Programming Languages The First Functional Programming

### The Arithmetic Operators. Unary Operators. Relational Operators. Examples of use of ++ and

The Arithmetic Operators The arithmetic operators refer to the standard mathematical operators: addition, subtraction, multiplication, division and modulus. Op. Use Description + x + y adds x and y x y

### The Arithmetic Operators

The Arithmetic Operators The arithmetic operators refer to the standard mathematical operators: addition, subtraction, multiplication, division and modulus. Examples: Op. Use Description + x + y adds x

### Relational Expressions. Boolean Expressions. Boolean Expressions. ICOM 4036 Programming Languages. Boolean Expressions

ICOM 4036 Programming Languages Ch7. Expressions & Assignment Statements Arithmetic Expressions Overloaded Operators Type Conversions Relational and Boolean Expressions Short-Circuit Evaluation Assignment

### Outline. Performing Computations. Outline (cont) Expressions in C. Some Expression Formats. Types for Operands

Performing Computations C provides operators that can be applied to calculate expressions: tax is 8.5% of the total sale expression: tax = 0.085 * totalsale Need to specify what operations are legal, how

### Motivation for typed languages

Motivation for typed languages Untyped Languages: perform any operation on any data. Example: Assembly movi 5 r0 // Move integer 5 (some representation) to r0 addf 3.6 r0 // Treat bit representation in

### Lexical Considerations

Massachusetts Institute of Technology Department of Electrical Engineering and Computer Science 6.035, Fall 2005 Handout 6 Decaf Language Wednesday, September 7 The project for the course is to write a

### Operators in C. Staff Incharge: S.Sasirekha

Operators in C Staff Incharge: S.Sasirekha Operators An operator is a symbol which helps the user to command the computer to do a certain mathematical or logical manipulations. Operators are used in C

### Review of the C Programming Language for Principles of Operating Systems

Review of the C Programming Language for Principles of Operating Systems Prof. James L. Frankel Harvard University Version of 7:26 PM 4-Sep-2018 Copyright 2018, 2016, 2015 James L. Frankel. All rights

### Computer Components. Software{ User Programs. Operating System. Hardware

Computer Components Software{ User Programs Operating System Hardware What are Programs? Programs provide instructions for computers Similar to giving directions to a person who is trying to get from point

### More Programming Constructs -- Introduction

More Programming Constructs -- Introduction We can now examine some additional programming concepts and constructs Chapter 5 focuses on: internal data representation conversions between one data type and

### C Language Part 1 Digital Computer Concept and Practice Copyright 2012 by Jaejin Lee

C Language Part 1 (Minor modifications by the instructor) References C for Python Programmers, by Carl Burch, 2011. http://www.toves.org/books/cpy/ The C Programming Language. 2nd ed., Kernighan, Brian,

### Control Structures. Outline. In Text: Chapter 8. Control structures Selection. Iteration. Gotos Guarded statements. One-way Two-way Multi-way

Control Structures In Text: Chapter 8 1 Control structures Selection One-way Two-way Multi-way Iteration Counter-controlled Logically-controlled Gotos Guarded statements Outline Chapter 8: Control Structures

### Statement level control structures

1 Statement level control structures CS 315 Programming Languages Pinar Duygulu Bilkent University Control Statements: Evolution 2 FORTRAN I control statements were based directly on IBM 704 hardware Much

### SOFTWARE DEVELOPMENT 1. Operators 2018W A. Ferscha (Institute of Pervasive Computing, JKU Linz)

SOFTWARE DEVELOPMENT 1 Operators 2018W (Institute of Pervasive Computing, JKU Linz) OPERATORS Operators are required to form expressions. Depending on the number of operands they take, they are called:

### Lexical Considerations

Massachusetts Institute of Technology Department of Electrical Engineering and Computer Science 6.035, Spring 2010 Handout Decaf Language Tuesday, Feb 2 The project for the course is to write a compiler

### Primitive Types. Four integer types: Two floating-point types: One character type: One boolean type: byte short int (most common) long

Primitive Types Four integer types: byte short int (most common) long Two floating-point types: float double (most common) One character type: char One boolean type: boolean 1 2 Primitive Types, cont.

### Two Types of Types. Primitive Types in Java. Using Primitive Variables. Class #07: Java Primitives. Integer types.

Class #07: Java Primitives Software Design I (CS 120): M. Allen, 13 Sep. 2018 Two Types of Types So far, we have mainly been dealing with objects, like DrawingGizmo, Window, Triangle, that are: 1. Specified

### HANDLING NONLOCAL REFERENCES

SYMBOL TABLE A symbol table is a data structure kept by a translator that allows it to keep track of each declared name and its binding. Assume for now that each name is unique within its local scope.

### Chapter 7. Additional Control Structures

Chapter 7 Additional Control Structures 1 Chapter 7 Topics Switch Statement for Multi-Way Branching Do-While Statement for Looping For Statement for Looping Using break and continue Statements 2 Chapter

### Data Types and Variables in C language

Data Types and Variables in C language Disclaimer The slides are prepared from various sources. The purpose of the slides is for academic use only Operators in C C supports a rich set of operators. Operators

### COP4020 Programming Languages. Control Flow Prof. Robert van Engelen

COP4020 Programming Languages Control Flow Prof. Robert van Engelen Overview Structured and unstructured flow Goto's Sequencing Selection Iteration and iterators Recursion Nondeterminacy Expressions evaluation

Visual C# 2005 2-1 Chapter 2 Using Data At a Glance Instructor s Manual Table of Contents Overview Objectives s Quick Quizzes Class Discussion Topics Additional Projects Additional Resources Key Terms

### 3. Java - Language Constructs I

Educational Objectives 3. Java - Language Constructs I Names and Identifiers, Variables, Assignments, Constants, Datatypes, Operations, Evaluation of Expressions, Type Conversions You know the basic blocks

### St. MARTIN S ENGINEERING COLLEGE Dhulapally, Secunderabad

St. MARTIN S ENGINEERING COLLEGE Dhulapally, Secunderabad-00 014 Subject: PPL Class : CSE III 1 P a g e DEPARTMENT COMPUTER SCIENCE AND ENGINEERING S No QUESTION Blooms Course taxonomy level Outcomes UNIT-I

### UNIT 3

UNIT 3 Presentation Outline Sequence control with expressions Conditional Statements, Loops Exception Handling Subprogram definition and activation Simple and Recursive Subprogram Subprogram Environment

### GO - OPERATORS. This tutorial will explain the arithmetic, relational, logical, bitwise, assignment and other operators one by one.

http://www.tutorialspoint.com/go/go_operators.htm GO - OPERATORS Copyright tutorialspoint.com An operator is a symbol that tells the compiler to perform specific mathematical or logical manipulations.

### UNIT- 3 Introduction to C++

UNIT- 3 Introduction to C++ C++ Character Sets: Letters A-Z, a-z Digits 0-9 Special Symbols Space + - * / ^ \ ( ) [ ] =!= . \$, ; : %! &? _ # = @ White Spaces Blank spaces, horizontal tab, carriage

### Expressions and Statements. Department of CSE, MIT, Manipal

Expressions and Statements Control Control: what gets executed, when, and in what order. Abstraction of control: Expression Statement Exception Handling Procedures and functions Expression vs. Statement

### CHAPTER 3 Expressions, Functions, Output

CHAPTER 3 Expressions, Functions, Output More Data Types: Integral Number Types short, long, int (all represent integer values with no fractional part). Computer Representation of integer numbers - Number

### Overview (4) CPE 101 mod/reusing slides from a UW course. Assignment Statement: Review. Why Study Expressions? D-1

CPE 101 mod/reusing slides from a UW course Overview (4) Lecture 4: Arithmetic Expressions Arithmetic expressions Integer and floating-point (double) types Unary and binary operators Precedence Associativity

### Programming in C++ 5. Integral data types

Programming in C++ 5. Integral data types! Introduction! Type int! Integer multiplication & division! Increment & decrement operators! Associativity & precedence of operators! Some common operators! Long

### Chapter 7. - FORTRAN I control statements were based directly on IBM 704 hardware

Levels of Control Flow: 1. Within expressions 2. Among program units 3. Among program statements Evolution: - FORTRAN I control statements were based directly on IBM 704 hardware - Much research and argument

### CONTENTS: Compilation Data and Expressions COMP 202. More on Chapter 2

CONTENTS: Compilation Data and Expressions COMP 202 More on Chapter 2 Programming Language Levels There are many programming language levels: machine language assembly language high-level language Java,

### Programming Languages, Summary CSC419; Odelia Schwartz

Programming Languages, Summary CSC419; Odelia Schwartz Chapter 1 Topics Reasons for Studying Concepts of Programming Languages Programming Domains Language Evaluation Criteria Influences on Language Design

### CPSC 3740 Programming Languages University of Lethbridge. Control Structures

Control Structures A control structure is a control statement and the collection of statements whose execution it controls. Common controls: selection iteration branching Control Structures 1 15 Howard

### Arithmetic Operators. Portability: Printing Numbers

Arithmetic Operators Normal binary arithmetic operators: + - * / Modulus or remainder operator: % x%y is the remainder when x is divided by y well defined only when x > 0 and y > 0 Unary operators: - +

### CSc 520 Principles of Programming Languages. 26 : Control Structures Introduction

CSc 520 Principles of Programming Languages 26 : Control Structures Introduction Christian Collberg Department of Computer Science University of Arizona collberg+520@gmail.com Copyright c 2008 Christian

### Unit-II Programming and Problem Solving (BE1/4 CSE-2)

Unit-II Programming and Problem Solving (BE1/4 CSE-2) Problem Solving: Algorithm: It is a part of the plan for the computer program. An algorithm is an effective procedure for solving a problem in a finite

### Prof. Navrati Saxena TA: Rochak Sachan

JAVA Prof. Navrati Saxena TA: Rochak Sachan Operators Operator Arithmetic Relational Logical Bitwise 1. Arithmetic Operators are used in mathematical expressions. S.N. 0 Operator Result 1. + Addition 6.

### Control Flow February 9, Lecture 7

Chapter 6 Control Flow February 9, Lecture 7 Expressions A simple object Literal constant Named variable Constant Or a function applied to arguments For built-in functions we use the term operator (like

### Java Notes. 10th ICSE. Saravanan Ganesh

Java Notes 10th ICSE Saravanan Ganesh 13 Java Character Set Character set is a set of valid characters that a language can recognise A character represents any letter, digit or any other sign Java uses

### CS2900 Introductory Programming with Python and C++ Kevin Squire LtCol Joel Young Fall 2007

CS2900 Introductory Programming with Python and C++ Kevin Squire LtCol Joel Young Fall 2007 Course Web Site http://www.nps.navy.mil/cs/facultypages/squire/cs2900 All course related materials will be posted

### LECTURE 18. Control Flow

LECTURE 18 Control Flow CONTROL FLOW Sequencing: the execution of statements and evaluation of expressions is usually in the order in which they appear in a program text. Selection (or alternation): a

### IPCoreL. Phillip Duane Douglas, Jr. 11/3/2010

IPCoreL Programming Language Reference Manual Phillip Duane Douglas, Jr. 11/3/2010 The IPCoreL Programming Language Reference Manual provides concise information about the grammar, syntax, semantics, and

### ! Non-determinacy (unspecified order) Maria Hybinette, UGA 2. 1 Landin adding sugar to a language to make it easier to read (for humans)

Maria Hybinette, UGA Big Picture: Control Flow Ordering in Program Execution CSCI: 4500/6500 Programming Languages Control Flow Chapter 6 1 Ordering/Flow Mechanisms:! Sequencing (statements executed (evaluated)

CS313D: ADVANCED PROGRAMMING LANGUAGE Computer Science department Lecture 2 : C# Language Basics Lecture Contents 2 The C# language First program Variables and constants Input/output Expressions and casting

### JAVA OPERATORS GENERAL

JAVA OPERATORS GENERAL Java provides a rich set of operators to manipulate variables. We can divide all the Java operators into the following groups: Arithmetic Operators Relational Operators Bitwise Operators