strings.py

#Using python to manipulate strings

'''
Python can be used to manipulate strings, which can 
be expressed in several ways.

They can be enclosed in single quotes ('...') 
or double quotes ("...")

'\' can be used to escape quotes

Python strings cannot be changed — they are immutable.

We will also look at the built in function called len()
This function returns the length of a string:

Strings have a bunch of methods available.
capitalize() Converts the first character to upper case
casefold() Converts string into lower case
center() Returns a centered string
count() Returns the number of times a specified value occurs in a string
encode() Returns an encoded version of the string
endswith() Returns true if the string ends with the specified value
expandtabs() Sets the tab size of the string
find() Searches the string for a specified value and returns the position of where it was found
format() Formats specified values in a string
format_map() Formats specified values in a string
index() Searches the string for a specified value and returns the position of where it was found
isalnum() Returns True if all characters in the string are alphanumeric
isalpha() Returns True if all characters in the string are in the alphabet
isascii() Returns True if all characters in the string are ascii characters
isdecimal() Returns True if all characters in the string are decimals
isdigit() Returns True if all characters in the string are digits
isidentifier() Returns True if the string is an identifier
islower() Returns True if all characters in the string are lower case
isnumeric() Returns True if all characters in the string are numeric
isprintable() Returns True if all characters in the string are printable
isspace() Returns True if all characters in the string are whitespaces
istitle() Returns True if the string follows the rules of a title
isupper() Returns True if all characters in the string are upper case
join() Converts the elements of an iterable into a string
ljust() Returns a left justified version of the string
lower() Converts a string into lower case
lstrip() Returns a left trim version of the string
maketrans() Returns a translation table to be used in translations
partition() Returns a tuple where the string is parted into three parts
replace() Returns a string where a specified value is replaced with a specified value
rfind()	 Searches the string for a specified value and returns the last position of where it was found
rindex() Searches the string for a specified value and returns the last position of where it was found
rjust() Returns a right justified version of the string
rpartition() Returns a tuple where the string is parted into three parts
rsplit() Splits the string at the specified separator, and returns a list
rstrip() Returns a right trim version of the string
split() Splits the string at the specified separator, and returns a list
splitlines() Splits the string at line breaks and returns a list
startswith() Returns true if the string starts with the specified value
strip() Returns a trimmed version of the string
swapcase() Swaps cases, lower case becomes upper case and vice versa
title() Converts the first character of each word to upper case
translate() Returns a translated string
upper() Converts a string into upper case
zfill() Fills the string with a specified number of 0 values at the beginning
'''

#The basics
'spam eggs'  # single quotes
'doesn\'t'  # use \' to escape the single quote...
"doesn't"  # ...or use double quotes instead
'"Yes," they said.'
"\"Yes,\" they said."


#New line
from tkinter import PIESLICE


s = 'First line.\nSecond line.'  # \n means newline
s  # without print(), \n is included in the output

print(s)  # with print(), \n produces a new line

#remove new line
print("ncshfsk", end="")   #remove new line, by default has new line character
print("jksfhuifyeuffbnfb")

#Raw string allows you to use backlash in string litteral
print('C:\some\name')  # here \n means newline!
print(r'C:\some\name')  # note the r before the quote


#String literals
print("""\
Usage: thingy [OPTIONS]
     -h                        Display this usage message
     -H hostname               Hostname to connect to
""")


#Concatenated
3 * 'un' + 'ium'
'Did' 'Coding'
text = ('Put several strings within parentheses '
        'to have them joined together.')
text
#This only works with two literals though, 
#not with variables or expressions:
prefix = 'Did'
#prefix 'Coding'
prefix + 'Coding'

#Indexing
'''
 +---+---+---+---+---+---+---+---+---+
 | D | i | d | C | o | d | i | n | g |
 +---+---+---+---+---+---+---+---+---+
 0   1   2   3   4   5   6   7   8   
-9  -8  -7  -6  -5  -4  -3  -2  -1
'''

word = 'Didcoding'
word[0]  # character in position 0
word[5]  # character in position 5
word[0:2]  # characters from position 0 (included) to 2 (excluded)
word[2:5]  # characters from position 2 (included) to 5 (excluded)
word[:2]   # character from the beginning to position 2 (excluded)
word[4:]   # characters from position 4 (included) to the end
word[-2:]  # characters from the second-last (included) to the end
word[:2] + word[2:]
word[:4] + word[4:]


#changing strings
# word[0] = 'P'
'P' + word[1:]
word[:2] + 'di'

#Sting length
s = 'bobby-didcoding'
len(s)


#Handy built-in functions
'''
When you don’t need fancy output but just want a quick display 
of some variables for debugging purposes, you can convert any 
value to a string with the repr() or str() functions.

The str() function is meant to return representations of values 
which are fairly human-readable, while repr() is meant to generate 
representations which can be read by the interpreter

You also have format().
The format() method formats the specified value(s) and insert them 
inside the string's placeholder '{}'.

'''
x=20
y=400
repr((x, y, ('spam', 'eggs')))
str((x, y, ('spam', 'eggs')))


print('{0} and {1}'.format('spam', 'eggs'))
print('{1} and {0}'.format('spam', 'eggs'))

# Advance Slicing

string = "I am Aimen Yaseen"

print(string[::2]) # [:]  // prints all the string
# [::2] // 3rd argument represents skipping of characters
# it prints 0th index then skip next and prints 2nd index
# 3rd argument is by default 1 i.e. no skipping

# Negative indexing
print(string[::-1])  # 3rd is be default 1 but when we give -1 it reverses the string
print(string[::-2])
# -2 will skip some characters

# built in methods 
# isalnum || isalpha
print(string.isalnum()) # False // because it contains spaces
print(string.isalpha()) # False // because it contains spaces
print(string.endswith("een")) # True
print(string.capitalize()) # capitalize 1st character of a sentence
print(string.count("e"))
print(string.lower())
print(string.upper())
print(string.replace("am", "are"))