Λογισμικό & κατασκευή λογ/κού

14 Δεκ 2013 (πριν από 7 χρόνια και 10 μήνες)

301 εμφανίσεις

BS0756

BSO763

UTTAM KUMAR

BSO854

SAHIL MONGA

Designed by
Guido van
Rossum

First appeared in 1991

Developer: Python Software Foundation

Stable Release: 2.6.3 on

2.10.2009

Influenced by ABC ,

ALGOL

Lisp ,
Modula
-
3,

Perl,

Java

Supports multiple

programming

(primarily

object
oriented,

imperative, and

functional)

Automatic

memory management

Often used as a

scripting language

The language has an open, community
-
based
development model

Dynamic

name resolution

(late binding)

automatically allocates and reclaims
("garbage collects") objects when no longer
used

Memory grows and shrink on demand

It keeps track of low
-
level memory details

programs are automatically compiled to
portable
byte code (.
pyc
)

runs on any platform with a
compatible
version of Python installed

Integer Variable

>>>
integer_variable

= 12345

Sting Variable

>>>
String_variable

= ‘Hi’

Float Variable

>>>
float_varialbe

= 123.456

>>> list = [‘a’,’b’,123,12.04]

Python knows a number of
compound

data
types, used to group together other values.
The most versatile is the
list
, which can be
written as a list of comma
-
separated values
(items) between square brackets. List items
need not all have the same type.

For Integer.

>>> x =
int
(input(“enter the number”))

For String.

>>> x =
str
(input(“enter the String”))

For Float.

>>> x = float(input(“enter the float”))

>>> x =
int

>>> if x < 0:

print('Negative changed to zero')

elif

x == 0:

print('Zero')

else:

print('More')

>>> # Measure some strings:

>>> a = ['cat', 'window', 'defenestrate']

>>> for x in a:

print(x,
len
(x))

NOTE:

#
is used for comment and

Len
is used for length of the string.

We can create a function that writes the Add
two numbers:

a,b
): #defining function

c=
a+b

print(c)

>>> Add(25,30) #for calling a function.

55

OPENING FILE

The open() command returns a file object.

<
filehandle
> = open(<filename>, <access type>)

Python can read, write or append to a file:

'w' = write

'a' = append

Create a file called “hello.txt” containing one line:
“Hello, world!”

>>>
myFile

= open("hello.txt", "r")

You can read the contents of the file into a single
string.

>>>
myFile

= open("hello.txt", "r")

>>>
myString

=
()

>>> print
myString

OUTPUT

Hello, world!

reading the file into a list of strings.

>>>
myFile

= open("
hello.txt","r
")

>>>
myStringList

=
()

>>> print
myStringList

['Hello, world!
\
n', "How
ya

doin
'?
\
n"]

>>> print
myStringList
[1]

How
ya

doin
'?

Open the file for writing or appending.

>>>
myFile

= open("new.txt",
"w")

Use the
<file>.write()

method.

>>>
myFile.write
("This is a new
file
\
n")

>>>
myFile.close
()

XML Parsing

DOM

SAX

Writing XML file using Python

includes many powerful data structures as
part of the core language and libraries

excellent support for Unicode and range of
encodings

implementations of the industry
-
standard
DOM and SAX interfaces

The Python standard library

implementation of Simple API for XML (SAX) and
Document Object Model (DOM)

PyXML

extends the standard library with additional XML
parsers

has adapters to allow more parsers to support the
SAX interface

4Suite, provided by
Fourthought

offers additional DOM implementations tailored for
different applications

DOM parser has to build an object model of
the whole document.

based on an object structure (structure it
Models)

SAX: Simple API for XML

Efficient memory utilization

Event
-
driven nature , faster processing

mpossible

Import
minidom

Create a new Document

Create User Element

Set Attributes to user element

Append user element in xml document

Write into an xml file

Close the file

Importing SAX and
Filehandler

Using
StartElement

&
EndElement

Parse the data

Display the contents

THANKS !!!