Chapter 12 Programming Concepts and Languages.

Chapter 12 Programming Concepts and Languages

Presentation Overview
Programming Concepts Problem-Solving Techniques The Evolution of Programming Approaches Programming Development and Documentation Tools Programming Errors The Software Development Life Cycle Major Programming Languages

Programming Concepts What makes up a programming language?

Programming Concepts What makes up a programming language?
Program – instructions telling a computer how to perform tasks

Program – instructions telling a computer how to perform tasks Programming languages – languages that communicate with the computer to create programs

Program – instructions telling a computer how to perform tasks Programming languages – languages that communicate with the computer to create programs Source code – text files that make up a programming language

Program – instructions telling a computer how to perform tasks Programming languages – languages that communicate with the computer to create programs Source code – text files that make up a programming language Four main computer language programming elements are variables, executable statements, looping, and decision statements.

Programming Concepts High-Level versus Low-Level Languages

Programming Concepts High-Level versus Low-Level Languages
Low-level language (machine code) is a binary language consisting of 1s and 0s; runs faster and takes up less disk space.

Programming Concepts High-Level versus Low-Level Languages
Low-level language (machine code) is a binary language consisting of 1s and 0s; runs faster and takes up less disk space. High-level language is similar to natural languages, making it easier to learn and use.

Programming Concepts Each generation of programs builds on the contributions of the group of languages that preceded it.

Programming Concepts Classic Programming Elements

Programming Concepts Classic Programming Elements
Variable – data value stored in computer memory

Variable – data value stored in computer memory Executable statement –performs an action and then proceeds to the next statement in sequence

Variable – data value stored in computer memory Executable statement –performs an action and then proceeds to the next statement in sequence Looping – allows a program to return to a previously executed instruction and repeat it

Variable – data value stored in computer memory Executable statement –performs an action and then proceeds to the next statement in sequence Looping – allows a program to return to a previously executed instruction and repeat it Decision statement – point in a program where different actions may be performed depending on specific conditions

Programming Concepts Looping allows a computer program to continuously repeat the same steps, such as a program designed to direct a traffic light to display yellow, red, and green lights at a consistent rate.

Programming Concepts Using an if-then statement based on a particular action, such as pushing the crosswalk button, a program can interrupt the looping pattern, making the program more useful.

Problem-Solving Techniques
Top-down design approach helps programmers break a large project into manageable parts. Breakdown process continues until there are no more steps.

Problem-Solving Steps

Problem-Solving Steps Identify the problem.

Problem-Solving Steps Identify the problem. Analyze the problem.

Problem-Solving Steps Identify the problem. Analyze the problem. Brainstorm solutions and choose the best one.

Problem-Solving Steps Identify the problem. Analyze the problem. Brainstorm solutions and choose the best one. Write the algorithm.

Problem-Solving Steps Identify the problem. Analyze the problem. Brainstorm solutions and choose the best one. Write the algorithm. Prototype the solution.

Problem-Solving Steps Identify the problem. Analyze the problem. Brainstorm solutions and choose the best one. Write the algorithm. Prototype the solution. Implement and test the solution.

Step-by-step pseudocode algorithm for changing a lightbulb.

The Evolution of Programming Approaches
Structured Programming

Structured Programming Creates groups of instructions as independent elements.

Structured Programming Creates groups of instructions as independent elements. Structured groups of instructions are built on a routine, which is a section of a program to handle a function.

Structured Programming Creates groups of instructions as independent elements. Structured groups of instructions are built on a routine, which is a section of a program to handle a function. A routine is broken down into steps to accomplish the function.

Modules

Modules Code modules handle separate components of a program.

Modules Code modules handle separate components of a program. Each module is a solid portion of a larger structure.

Modules Code modules handle separate components of a program. Each module is a solid portion of a larger structure. Modules are reusable, and modularity helps in tracking down errors.

Modules Code modules handle separate components of a program. Each module is a solid portion of a larger structure. Modules are reusable, and modularity helps in tracking down errors. A macro is a recording of steps to perform a repetitive task.

Object-Oriented Programming

Object-Oriented Programming Object-oriented programming (OOP) defines each module (object) with definite rules for interfacing and a protected set of variables.

Object-Oriented Programming Object-oriented programming (OOP) defines each module (object) with definite rules for interfacing and a protected set of variables. Protected variables allow a programmer to prevent data from being altered during program execution.

Rapid Application Development

Rapid Application Development Rapid application development (RAD) reduces cost by decreasing time needed to develop a project.

Rapid Application Development Rapid application development (RAD) reduces cost by decreasing time needed to develop a project. Programmers using RAD follow guidelines • Use visual development (4GL) tools when possible • Rapidly prototype new projects • Approach coding with these priorities – Use existing code first. – Buy someone else’s code second. – Write new code last.

Programming Development and Documentation Tools
Compilers and Interpreters

Compilers and Interpreters Compiler – program that translates programming language source code into machine code

Compilers and Interpreters Compiler – program that translates programming language source code into machine code Interpreter – translates instructions one-by-one as source code is being executed; identifies errors as they are encountered, including the line containing the error

Debuggers

Debuggers Debugger – a software tool that helps programmers find errors quickly.

Debuggers Debugger – a software tool that helps programmers find errors quickly. Allows programmers to examine closely what is happening when a program runs.

Debuggers Debugger – a software tool that helps programmers find errors quickly. Allows programmers to examine closely what is happening when a program runs. Usually an integral component of compilers and interpreters.

Document Tools

Document Tools Flowchart – provides a visual diagram of an algorithm

Document Tools Flowchart – provides a visual diagram of an algorithm CASE tools – help programming team schedule and coordinate its operations

Document Tools Flowchart – provides a visual diagram of an algorithm CASE tools – help programming team schedule and coordinate its operations Comment – informal message inserted into a program usually to explain source code to later users

These symbols are used in flowcharts to represent the logic of a program.

Flowcharts help programmers visualize the steps in a software program.

Programming Errors What programming errors are in programs?

Programming Errors What programming errors are in programs?
Syntax errors – typing errors or misunderstanding of rules of the language

Syntax errors – typing errors or misunderstanding of rules of the language Logic errors – program instructs computer to perform an action incorrectly

Syntax errors – typing errors or misunderstanding of rules of the language Logic errors – program instructs computer to perform an action incorrectly Run-time errors – mistakes that occur when an application is running (crash or infinite loop)

Syntax errors – typing errors or misunderstanding of rules of the language Logic errors – program instructs computer to perform an action incorrectly Run-time errors – mistakes that occur when an application is running (crash or infinite loop) Style errors – poorly written programming code that may cause dissatisfaction with program

The Software Development Life Cycle
What are the steps in the software development life cycle? The software development life cycle involves planning, designing, implementing, testing, and release of application software.

Major Programming Languages
Commonly used programming languages

Machine Code

Machine Code programming language that computers actually read and interpret

Machine Code programming language that computers actually read and interpret machine code written in a binary string of 1s and 0s

Machine Code programming language that computers actually read and interpret machine code written in a binary string of 1s and 0s difficult to memorize the long binary strings that comprise the machine code

Assembly Language

Assembly Language uses symbols and words to represent elements of machine code

Assembly Language uses symbols and words to represent elements of machine code must be converted to machine code by a compiler

Assembly Language uses symbols and words to represent elements of machine code must be converted to machine code by a compiler runs fastest and uses least memory

Assembly Language uses symbols and words to represent elements of machine code must be converted to machine code by a compiler runs fastest and uses least memory programs are difficult to write and development times are lengthened

COBOL

COBOL used chiefly for business applications by large institutions and companies

COBOL used chiefly for business applications by large institutions and companies is slow and cumbersome language, but has large body of existing code and many programmers know the language

RPG

RPG commonly used in business environments

RPG commonly used in business environments inefficient, but simplifies coding of database applications

RPG commonly used in business environments inefficient, but simplifies coding of database applications is familiar to many programmers

RPG commonly used in business environments inefficient, but simplifies coding of database applications is familiar to many programmers often used on midrange and mainframe computers

FORTRAN

FORTRAN for many years, the language of choice for math, science, and engineering projects

FORTRAN for many years, the language of choice for math, science, and engineering projects still in use today in factories and laboratories

BASIC

BASIC high-level language that is friendlier and more natural than COBOL or FORTRAN

BASIC high-level language that is friendlier and more natural than COBOL or FORTRAN runs slowly, but faster to develop for programmers

BASIC high-level language that is friendlier and more natural than COBOL or FORTRAN. runs slowly, but faster to develop for programmers. This sequence of code will print the numbers 1 to 10.

Visual Basic (VB)

Visual Basic (VB) language of choice for developing software prototypes or for developing interfaces for Windows platforms

Visual Basic (VB) language of choice for developing software prototypes or for developing interfaces for Windows platforms quick and easy to develop, but run slowly and is demanding of RAM and disk space

Visual Basic (VB) language of choice for developing software prototypes or for developing interfaces for Windows platforms quick and easy to develop, but run slowly and is demanding of RAM and disk space supports graphic interfaces

C

C compromise between high-level and low-level languages, containing components of BASIC and assembly language

C compromise between high-level and low-level languages, containing components of BASIC and assembly language not as easy to read as BASIC, but runs considerably faster and uses less space

C++

C++ superset of C; any C program should run in C++

C++ superset of C; any C program should run in C++ added features such as object-oriented programming

C++ superset of C; any C program should run in C++. added features such as object-oriented programming. This sequence of code will print the numbers 1 to 10.

C#

C# modern object-oriented language derived from C++ and Java

C# modern object-oriented language derived from C++ and Java combines productivity of Visual Basic with power of C++

C# modern object-oriented language derived from C++ and Java combines productivity of Visual Basic with power of C++ allows use of features in Microsoft.NET framework, C, and Microsoft’s Component Object Model (COM)

Scripting Languages

Scripting Languages interpreted language that is relatively easy to learn and use

Scripting Languages interpreted language that is relatively easy to learn and use explains what a computer should do in English-like terms but not precisely how the computer should do it

Scripting Languages interpreted language that is relatively easy to learn and use explains what a computer should do in English-like terms but not precisely how the computer should do it Hypertext Markup Language (HTML), JavaScript, VBScript, and perl are scripting languages

Major Program- ming Languages
This sequence of code directs a browser to display buttons users can click to change the background color within the Web browser window.

DHTML

DHTML allows Web page designers to alter contents of Web page screen dynamically

DHTML allows Web page designers to alter contents of Web page screen dynamically allows viewer actions to change contents of a Web page

DHTML allows Web page designers to alter contents of Web page screen dynamically allows viewer actions to change contents of a Web page displays faster than HTML

DHTML allows Web page designers to alter contents of Web page screen dynamically allows viewer actions to change contents of a Web page displays faster than HTML higher quality appearance and more graphically responsive to user actions

XHTML

XHTML allows Web pages to separate their content from the format supported by a Web page

XHTML allows Web pages to separate their content from the format supported by a Web page screens with different sizes and resolutions can display the same Web page content without the Web designer having to write specialized versions for each

Wireless Markup Language (WML)

Wireless Markup Language (WML) created specifically for small systems such as cell phones and handheld computers

Wireless Markup Language (WML) created specifically for small systems such as cell phones and handheld computers allows designers to build pages that work for small screens with limited display and input capabilities

On the Horizon Based on the information presented in this chapter and your own experience, what do you think is on the horizon?

Chapter 12 Programming Concepts and Languages.

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