User:Selena Savic/TechdazeNotes

IMPERATIVE LANGUAGES

Python

DECLARATIVE LANGUAGES

CSS

Regular expressions - finite state machine
uses:

• SEARCH (=check for matches)
  
• FINDALL (=extract; returns a list of matches)
  
• SUB / FIND AND REPLACE (=automatic markup)
  
• SPLIT (=cut up)
  

special characters:

• [ ] - character class; either, or
  

0123456789 = any digit, from 0 to 9 = 0-9
a-z = any letter
? = 0, 1
+ = 1>

• = 0>
  

. = any character (like star in command line)
{ } = n, m; modifiers (expanding patterns)
( ) = grouping
\d = digit
\w = word
\D = non-digit
\W = non-word
\n = new line
\s = space, any number of white spaces
\S = non-space
\b = word boundary
\0 = the match
1, $, \b = anchors

python: >>> print "hello"
hello
>>> print "h\ello"
h\ello
>>> print "h\tello" #\t stands for "tab"
h ello
>>> print "h\nello"
h
ello
>>> print r"h\nello" # r stands for "raw"
h\nello