Python Strings

• use "" or ''
• for multiple lines use triple quotes ''' '''
• strings are iterable, i.e. can look up characters in the string by index
• can use negative indexes
• strings are immutable, must create a new string
• concatenate strings with + and multiple with *
  • these will not automatically add spaces between strings
• string.upper() and string.lower() change the case of all the characters in the string to be upper or lower
• string.capitalize() will just capitalize the first letter
• create new string using using .format()
  • it looks for curly brackets and inserts the parameter
  • example: 'William {}'.format('Faulkner') creates the string 'William Faulkner'
  • example:

    n1 = input('Enter a noun: ')
    v = input('Enter a verb: ')
    adj = input('Enter a adj: ')
    n2 = input('Enter a noun: ')
    
    r = '''The {} {} the {}{}'''.format(n1, v, adj, n2)

• .split(delimiter) will split into multiple strings at the delimiter
  • the delimiter is not in either string
• .join() lets you add new characters to a string
  • example:

    first_three = 'abc'
    result = '+'.join(first_three)

    result is a+b+c
  • can also use with lists. example:

    words = ['The', 'fox', 'jumped', 'over', 'the', 'fence', '.']
    one_string = ' '.join(words)

    one_string is 'The fox jumped over the fence .'
• .strip() strips leading and following white space from a string
• can use in and not in keywords
• '\' escape character
  • \n newline
• slicing: name[start_index:end_index]
  • start_index is included, end_index is not included
  • works with strings and lists
  • example:

    ivan = 'In place of death there was light.'
    ivan[0:17]

    gives us 'In place of death'ivan[17:33]gives us ' there was light'
  • example:

    list = ['a', 'b', 'c', 'd', 'e']
    list[0:3]

    now list is ['a', 'b', 'c']
  • if start_index is 0 you can leave it empty [:end_index]
  • if end_index is last index in the iterable you can leave it empty [start_index:]
  • leaving both empty [:] returns the original iterable
• .replace(param1, param2) replaces every occurrence of one character with another
  • first param is the string to replace and the second param is the replacement string
  • example:

    equ = 'All animals are equal.'
    equ = equ.replace('a', '@')

    equ is now 'All @nim@ls @re equ@l.'
• string.index('character') returns the first index the param string occurs at