# Ordinary string literals in Python. Escape sequences can be used

# to embed various special characters inside string literals.

s1 = "Hello there,\tworld!"

s2 = ""

import unicodedata as uu # properties of Unicode characters

# Python 3 strings are sequences of arbitrary Unicode characters.

for c in range(100,10100,500):

cc = chr(c)

s2 += cc

print(f"Character {cc} is {uu.name(cc)}, in category {uu.category(cc)}.")

# Old time byte strings can contain only ASCII characters 0-127.

sb = b'Only ASCII characters allowed here!\x60'

print(f"String s1 is <{s1}>.")

print(f"String s2 is <{s2}>.")

print(f"String sb is {sb}.")

a = 42

b = 123.45678

# Python 3.6 formatted string. There is a whole minilanguage available.

s3 = f"a is now {a} (which is {a:x} in hex), and b is now {b:.3f} \

which is {b:e} in scientific notation."

print(s3) # note the rounding of decimal number b

# The string does not remember where its characters came from.

a = 99

print(s3) # still says that a is 42

s4 = f"a is now {a}, b is now {b:7.3}."

print(s4) # Here a is 99

# Format placeholders are evaluated once. They are compiled to Python

# bytecode before executing the program, so syntax errors are revealed

# before the script starts running. Uncomment to see this happen.

#print(f"a is now {a:!4&^#}")

a = 42

print(s4) # a is still 99 inside the string

# And yet another way to compose strings from smaller pieces.

from string import Template

tt = Template("$who likes $food.")

# Python's flexibility to allow arbitrary keyword arguments in functions

# really displays its power and usefulness here.

print(tt.substitute(who="Bob", food="sushi"))

print(tt.substitute(who="Jack", food="steak"))

# The old-timey string interpolation operator % behaves like in C.

s2 = "a is now %3d, b is now %.4f." % (a, b)

print(s2)

# Strings are iterable, and can thus be processed like other iterables.

it = iter(s1)

print(next(it)) # H

print(next(it)) # e

for x in it:

print(ord(x), end = ' ') # whole bunch of Unicode codepoints

print() # line break

# Raw strings can be handy with regexes and other things that handle

# special characters differently from Python.

s5 = r'Bunch of % \ special characters as they are.'

print(s5)

# Unicode has lots of crazy stuff.

# https://mortoray.com/2013/11/27/the-string-type-is-broken/

s6 = u'noe\u0308l'

print(s6)

print("".join(reversed(s6))) # reversing unicode string is tricksy

print(s6[::-1]) # clever indexing reverse taken from Stack Overflow

# Taken from "WTF Python". What is going on here?

value = 11

valuе = 32

print(value) # 11

print(valuе) # 32

# Some handy methods on strings.

print(s1.title())

print(s1.upper())

print(s1.lower())

print(s1.capitalize())

# Add whitespace to left, right or both sides to reach given length.

print('1234'.center(10))

print('1234'.ljust(10))

print('1234'.rjust(10))

# In principle all string operations could be done using methods

# that we already have, but it's pointless to reinvent the wheel

# unless you feel like exercising.

from string import capwords

s = "let us capitalize every word of this sentence."

print(capwords(s))

# This one would not be too difficult to do on our own.

print(" ".join([x.capitalize() for x in s.split()]))