Python: Input-Output (Solutions)

Raw input

1. Solution:

   food = raw_input("What is your favourite food? ")
   
   print "I also like", food
   

2. Solution:

   a_and_b = raw_input("Write two integers: ")
   words = a_and_b.split()
   a = int(words[0])
   b = int(words[1])
   
   answer = raw_input("how much is " + str(a) + " " + str(b) " ? ")
   result = int(answer)
   
   print a + b == answer
   

3. Solution:

   key = raw_input("give me a key: ")
   value = raw_input("give me a value: ")
   
   dictionary = {key: value}
   # or
   dictionary = {}
   dictionary[key] = value
   
   print "dictionary =", dictionary
   

4. Solution:

   name = raw_input("Give me your full name: ")
   
   fixed_words = [word[0].upper() + word[1:].lower()
                        for word in name.split()]
   print "Your name is:", " ".join(fixed_words)
   

Filesystem

1. Solution:

   f = open("data/aatable", "r")
   # or
   f = open("data/aatable")
   
   rows = f.readlines()
   print type(rows)                           # list
   print type(rows[0])                        # str
   print len(rows)
   
   f.close()
   

2. Solution:

   f = open("data/aatable")
   
   first_row = f.readline()
   print "The first row is: ", first_row
   
   remaining_rows = f.readlines()
   print "another", len(remaining_rows), " rows are left"
   
   remaining_rows_bis = f.readlines()
   print "then, another", len(remaining_rows_bis), "rows are left"
   
   # In the last case, 0 rows should be left: the first
   # readlines() already read all the lines of f
   
   f.close()
   

3. Solution:

   f = open("output.txt", "w")
   f.write("check one two three check")
   f.close()
   
   g = open("output.txt", "r")
   print g.readlines()
   g.close()
   

4. Solution:

   verses = [
       "S'i fosse fuoco, arderei 'l mondo"
       "s'i fosse vento, lo tempestarei"
   ]
   
   f = open("poetry.txt", "w")
   f.write("\n".join(verses))
   f.close()
   

   Now let’s try with "a":

   f2 = open("poetry2.txt", "a")
   f2.write(verses[0] + "\n")
   f2.close()
   
   f2 = open("poetry2.txt", "a")
   f2.write(verses[1] + "\n")
   f2.close()
   

   And if we use "w" on "poetry2.txtx":

   f = open("poetry2.txt", "w")
   # Here we do absolutely nothing to f, we just close it
   f.close()
   

   we can see that now "poetry2.txt" is empty! This happens as a consequence of using "w" instead of "a".

5. Let’s write in the file trick.py:

   myself = open("trick.py")
   print myself.read()
   myself.close()
   

   Let’s execute the file to verify that it’s working as we want: from a shell, let’s write:

   python trick.py