String_1.py

# Basic python string problems -- no loops. Use + to combine strings, len(str) is the number of chars in a String,
# str[i:j] extracts the substring starting at index i and running up to but not including index j.

# ----------------------------------------------------------------------------------------------------------------------
#
# Given a string name, e.g. "Bob", return a greeting of the form "Hello Bob!".
#
#
# hello_name('Bob') → 'Hello Bob!'
# hello_name('Alice') → 'Hello Alice!'
# hello_name('X') → 'Hello X!'

def hello_name(name):
    return "Hello " + name + "!"


# ----------------------------------------------------------------------------------------------------------------------
#
# Given two strings, a and b, return the result of putting them together in the order abba,
# e.g. "Hi" and "Bye" returns "HiByeByeHi".
#
#
# make_abba('Hi', 'Bye') → 'HiByeByeHi'
# make_abba('Yo', 'Alice') → 'YoAliceAliceYo'
# make_abba('What', 'Up') → 'WhatUpUpWhat

def make_abba(a, b):
    return a + b + b + a


# ----------------------------------------------------------------------------------------------------------------------
#
# The web is built with HTML strings like "<i>Yay</i>" which draws Yay as italic text.
# In this example, the "i" tag makes <i> and </i> which surround the word "Yay".
# Given tag and word strings, create the HTML string with tags around the word, e.g. "<i>Yay</i>".
#
#
# make_tags('i', 'Yay') → '<i>Yay</i>'
# make_tags('i', 'Hello') → '<i>Hello</i>'
# make_tags('cite', 'Yay') → '<cite>Yay</cite>'

def make_tags(tag, word):
    return "<" + tag + ">" + word + "</" + tag + ">"


# ----------------------------------------------------------------------------------------------------------------------
#
# Given an "out" string length 4, such as "<<>>", and a word,
# return a new string where the word is in the middle of the out string, e.g. "<<word>>".
#
#
# make_out_word('<<>>', 'Yay') → '<<Yay>>'
# make_out_word('<<>>', 'WooHoo') → '<<WooHoo>>'
# make_out_word('[[]]', 'word') → '[[word]]'

def make_out_word(out, word):
    return out[0] + out[1] + word + out[2] + out[3]


# ----------------------------------------------------------------------------------------------------------------------
#
# Given a string, return a new string made of 3 copies of the last 2 chars of the original string.
# The string length will be at least 2.
#
#
# extra_end('Hello') → 'lololo'
# extra_end('ab') → 'ababab'
# extra_end('Hi') → 'HiHiHi'

def extra_end(str):
    if len(str) >= 2:
        return str[-2:] * 3


# ----------------------------------------------------------------------------------------------------------------------
#
# Given a string, return the string made of its first two chars, so the String "Hello" yields "He".
# If the string is shorter than length 2, return whatever there is, so "X" yields "X",
# and the empty string "" yields the empty string "".
#
#
# first_two('Hello') → 'He'
# first_two('abcdefg') → 'ab'
# first_two('ab') → 'ab'

def first_two(str):
    return str[0:2]


# ----------------------------------------------------------------------------------------------------------------------
#
# Given a string of even length, return the first half. So the string "WooHoo" yields "Woo".
#
#
# first_half('WooHoo') → 'Woo'
# first_half('HelloThere') → 'Hello'
# first_half('abcdef') → 'abc'

def first_half(str):
    return str[:(len(str) / 2)]


# ----------------------------------------------------------------------------------------------------------------------
#
# Given a string, return a version without the first and last char, so "Hello" yields "ell".
# The string length will be at least 2.
#
#
# without_end('Hello') → 'ell'
# without_end('java') → 'av'
# without_end('coding') → 'odin'

def without_end(str):
    return str[1:(len(str) - 1)]


# ----------------------------------------------------------------------------------------------------------------------
# #
# Given 2 strings, a and b, return a string of the form short+long+short,
# with the shorter string on the outside and the longer string on the inside.
# The strings will not be the same length, but they may be empty (length 0).
#
# combo_string('Hello', 'hi') → 'hiHellohi'
# combo_string('hi', 'Hello') → 'hiHellohi'
# combo_string('aaa', 'b') → 'baaab'

def combo_string(a, b):
    if len(a) > len(b):
        return b + a + b
    else:
        return a + b + a


# ----------------------------------------------------------------------------------------------------------------------
#
# Given 2 strings, return their concatenation, except omit the first char of each. The strings will be at least
# length 1.
#
#
# non_start('Hello', 'There') → 'ellohere'
# non_start('java', 'code') → 'avaode'
# non_start('shotl', 'java') → 'hotlava'

def non_start(a, b):
    return a[1:] + b[1:]

# ----------------------------------------------------------------------------------------------------------------------
#
# Given a string, return a "rotated left 2" version where the first 2 chars are moved to the end.
# The string length will be at least 2.
#
# left2('Hello') → 'lloHe'
# left2('java') → 'vaja'
# left2('Hi') → 'Hi'

def left2(str):
  return str[2:]+str[:2]

# ----------------------------------------------------------------------------------------------------------------------