Basics 12/01 - Strings

# # Expressions Vs Statements

# iq = 100 # this entire line is a statement
# user_age = iq / 5 # "iq / 5" is an expression, that produces a value. In this case the expression is within a statement

# # a statement is an entire line of code that performs an action, in the above case the entire line is a statement

# # Augmented Assignment Operator

# # some_value = 5
# # some_value = some_value + 2
# # some_value +=  2 # shorthand version of the above. To work the variable requires a pre-existing value
# #                  # works with several operators e.g +,-,*,/ - these go to the left of the = sign

# # # print(some_value)

# # Strings - Str - a string is simply a line of text
# "such as this,"
# 'or this! You can even put numbers like 73 in it!'

# # for individual variables on a single line
# username = 'stinkycoder'
# password = 'goongaginga'

# # triple quotes for strings that cover multiple lines of text
# long_string = '''
# WOW
# O O
# ___
# '''
# # print(long_string)

# first_name = 'bob'
# last_name = 'billy'
# full_name = first_name + ' ' + last_name # the additional quotes allow for a space between names

# print(full_name)

# # String Concatenation - simply, adding strings together
# print('hello' + 'bob') # only works between strings, e.g. could not do hello + 5 like this

#type conversion
# print(type(str(100))) # 100 has been converted into a string
# print(type(int(str(100)))) # 100 has been converted into a string, then back to an int

# a = str(100)
# b = int(a)
# c = type(b)

# print(c) # performs same function as our previous conversion, using variables

# # Escape Sequence - issues with double quotes and similar
# # weather = "it's "kind of" sunny" - situations like this don't work
# weather = "\it\'s \"kind of\" sunny" # using backslash \ allows python to see that this is a full string
# # other special functions: \t creates a tab spacing effect, \n creates a new line
# print(weather)

#Formatted strings - for more dynamic situations e.g. changing names etc

#name = 'Jimbo'
#age = '73'
# print('Hi' + ' ' + name + '. You are ' + str(age) + ' years old!') # works but is extremely clunky
# print(f'hi {name}. You are {age} years old.') # significantly cleaner version using f to denote formatting, and {} for variables
# print('hi {}. You are {} years old.'.format(name, age)) # alternative method - using numbers from 0 can change rotation of info
# print('hi {new_name}. You are {age} years old.'.format(new_name = 'sally', age = 100)) # also works
#.format slightly more complicated to deal with than just using f at the start of a string, but may be common in older code

# # String Indexes
# selfish = 'me me me'
#           #01234567 # each shelf corresponds to a value in the sting, e.g 0 = m, 1 = e, 3 = space etc
# print(selfish[0]) # this will print the letter "m", by finding the data indexed at that point in the string
# # [start] first item in the brackets is the start of the search
# # [start:stop] allows you to set a place to end the search as well
# print(selfish[0:4]) # prints items 0-4 in the variable, in this case "me m"
# # [start:stop:stepover] stepover allows you to skip a certain number
# print(selfish[0:8:2]) # in this case the step is 2, so it will skip every second item
# print(selfish[-1]) # this will effectively start at the end and work backwards, e.g. here it will start at "e" which is 7th
# print(selfish[::-1]) # this will entirely reverse the string, on higher numbers will skip as usual backwards instead

# Immutability - cannot be changed. Strings are immutable. The only way to change it is to completely reassign variable