Programming lesson1

PROGRAMMING
3RD GRADING PERIOD – LESSON 2

What is Programming?

Programming is a creative process done
by programmers to instruct a computer
on how to do a task.
Programming is instructing a computer
to do something for you with the help of
a programming language.

What is a Program?
 In computing, a program is a specific set of ordered
operations for a computer to perform. In the modern
computer that John von Neumann outlined in 1945,
the program contains a one-at-a-time sequence of
instructions that the computer follows. Typically, the
program is put into a storage area accessible to the
computer. The computer gets one instruction and
performs it and then gets the next instruction.

What is a Programmer?

A programmer is a person who
prepares instructions for
computers.

A programmer needs to develop a welldefined concept of how to solve a
problem. Then this concept must be
translated into a computer language.
Finally, the program needs to be typed
into the computer, tested, and
debugged before being placed into
service.

What is a Programming Language?

Programming Language is a
language used to give
instructions to computers.

During the 1960s and 1970s, a huge variety
of programming languages were developed,
most of which are no longer in wide use.
Moreover, a substantial amount of
programming is now done with special
program development tools (e.g., Visual
Basic), or in programming languages that
pertain to specific pieces of software (e.g.,
Maple) rather than by simply writing
instructions in a general-purpose language.

The following is a rough classification of
programming languages.
1. General-purpose languages for large, complex programs: PL/I, C, C++, Pascal,
Modula-2, Ada, Java, C#.
2. General-purpose languages for smaller programs: BASIC, Visual Basic, Pascal,
Python.
3. Mathematical calculation, science, and engineering: FORTRAN, APL, Maple, and
the general-purpose languages named above.
4. Business data processing: COBOL, RPG. Where microcomputers are involved,
BASIC, C, and languages associated with specific database products are also
widely used.
5. Artificial intelligence and programs of extreme logical complexity: Lisp and
Prolog.
6. String handling and scripting: SNOBOL, REXX, Awk, Perl, Python, VBSCRIPT,
JavaScript.

Another useful classification is based
on the way the program is organized.
1. Sequential languages treat the program as
a series of steps, with an occasional GOTO
statement as a way of breaking out of the
sequence. In this category are FORTRAN,
BASIC, and COBOL(though COBOL also
allows programs to be written in a style
more like a block-structured language).

2.Block-structured languages
encourage structured
programming by allowing the
programmer to group statements
into functional units. This category
originated with Algol and now
includes Pascal, Modula-2, C, PL/I,
and Ada.

Structured Programming?
 Structured programming is a programming technique
that emphasizes clear logic, modularity, and avoidance
of GO TO statements (which are intrinsically errorprone).
 Structured programming is a style of programming
designed to make programs more comprehensible
and programming errors less frequent.

3.Object-oriented languages allow the
programmer to define new data types
and associate procedures with them.
Languages of this type include C++,
Java, C#, object-oriented extensions of
Pascal, and Smalltalk.

4.Symbolic languages allow the program
to examine and modify itself, treating
instructions as data. Lisp and Prolog fall
into this category.

Although names of some
programming languages are
normally written in all capital
letters, names of most languages
are not, even if they are acronyms.
Usage varies from language to
language. With some, usage has
shifted over the years.

BASIC?
 BASIC (Beginner’s All-purpose Symbolic Instruction
Code) a computer language designed by John Kemeny
and Thomas Kurtz in 1964 and popularized by
Microsoft in the 1970s.
 BASIC is good for programming simple calculations
quickly, and you do not have to learn much of the
language in order to begin using it.
 Because no declarations are required, programs can
be quite short.

 In the 1970s and 1980s, numerous software vendors,
especially Microsoft, added features to BASIC to
support STRUCTURED PROGRAMMING and a wide
variety of DATASTRUCTURES. Today, BASIC is one of
the most complex programming languages in wide
use, incorporating features from Pascal, FORTRAN,
and C. Line numbers are no longer necessary.
 However, BASIC is still easy for beginners to use, and
the newest BASIC compilers still accept programs
written in Kemeny and Kurtz’s original language.

BASIC program and its output
10 REM Temperature conversion program
20 PRINT ”Temperature in Fahrenheit”;
30 INPUT F
40 LET C=(F-32)*5/9
50 PRINT F;” F equals ”;
60 PRINT C;” C”
70 END
Temperature in Fahrenheit? 98
98 F equals 36.66667 C

VISUAL BASIC?
 One of the first successful interactive development
environments for Windows programming, introduced by
Microsoft in 1991.
 Programmers can lay out the program’s windows graphically
and write BASIC code to specify what happens when each
button is clicked or other events occur.
 Any part of the layout or code can be changed at any time.
 Unlike in earlier Windows programming environments, the
programmer need not write any general code to initialize
windows, handle events, or interact with the operating
system.

The current version is called Visual Basic .NET
or VB.NET and uses the .NET Framework for
fully object-oriented programming. Similar
products for other programming languages
include Microsoft’s Visual C++ and Visual C#
and Borland’s Delphi and Kylix (for Pascal),
JBuilder (for Java), and C++ Builder.

.NET Framework?
 An application program interface (API) for Microsoft Windows,
introduced in 2001 as a downloadable add-on to Windows 2000
and XP and included in subsequent versions of Windows.
 The purpose of the .NET Framework is to reduce the amount of
work programmers have to do, while at the same time increasing
reliability and introducing Java-like portability.
 The .NET Framework is fully object-oriented.
 The .NET Framework manages the memory used by each
program.
 Like Java, the .NET Framework normally compiles programs into
bytecode, a concise notation that is converted to machine
language when the program is ready to run.

Bytecode?
Bytecode is the compiled code that compilers for
Java and C# produce. It isn't true machine code
but a simpler code made up of instructions that
are one byte long.

Programming lesson1

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