python练习题园地（二）——String篇
String-1 > hello_name
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!’
Code:
def hello_name(name):
return 'Hello '+name+'!'
String-1 > make_abba
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*2+a
String-1 > make_tags
The web is built with HTML strings like “Yay“ which draws Yay as italic text. In this example, the “i” tag makes and which surround the word “Yay”. Given tag and word strings, create the HTML string with tags around the word, e.g. “Yay“.
make_tags(‘i’, ‘Yay’) → ‘Yay‘
make_tags(‘i’, ‘Hello’) → ‘Hello‘
make_tags(‘cite’, ‘Yay’) → ‘Yay‘
Code
def make_tags(tag, word):
return ('<%s>'+word+'</%s>')%(tag,tag)
String-1 > make_out_word
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. “<
make_out_word(‘<<>>’, ‘Yay’) → ‘<
make_out_word(‘<<>>’, ‘WooHoo’) → ‘<
make_out_word(‘[[]]’, ‘word’) → ‘[[word]]’
Code
def make_out_word(out, word):
return out[:2]+word+out[2:]
String-1 > extra_end
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’
Code:
def extra_end(str):
str_len=len(str)
return str[str_len-2:]*3
String-1 > first_two
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’
Code:
def first_two(str):
if len(str)<=2:
return str
else:
return str[:2]
String-1 > first_half
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’
Code:
def first_half(str):
return str[:int(len(str)/2)]
String-1 > without_end
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’
Code:
def without_end(str):
return str[1:len(str)-1]
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