Lab 6 - Python (Reloaded)


Objectives
  1. Review the following programming elements: if statements and string operations.
  2. Practice writing Python programs

If Statements

if <condition>:

<statements>

elif <condition>:

<statements>

else:

<statements>

Example: What is the output of the following program?

x = 9
y = 2 
if x/y>4: 
    print "if"
else:
    print "else"
print "freedom" 

Practice I: Maximum of 3 integers

Our first task is to write a program, which asks the user to input 3 integers and outputs the maximum of them.


String Operations

Consider the following string:

>>> x = "I am you are"

What would the following expressions produce?

>>> x[0]

>>> x[-1]

>>> x[2:4] + x[6:8]

>>> x[:4]

>>> x[5:]

>>> x[1:2] * 3

Given x, provide a way to access "you" with negative indices


Practice II : Strings

Creating String expressions

Execute the following statements in Python:
    import string
    str1 = "Go"
    str2 = "Terriers!"
Now, for each of the following values, construct a Python expression involving string operations on str1 and/or str2 that evaluates to that value.
  1.     "Go Terriers!"      use "+"
  2.     "GOT!"                      use "upper"
  3.     'Torriors!'            use "replace"

 

Using the "in" keyword

Consider the following expression:

>>> "base" in "datacase"

What is the type of this expression?

 

Reading strings from the terminal

Assume that the following raw_input statements are both executed:

>>> mine=raw_input("My favorite number: ")

>>> yours=raw_input("Your favorite number: ")

Write one or more statements that prints the sum of our (mine and yours) favorite numbers! (Hint: Don't forget that raw_input always gives you a string. How can you change the string to an integer?)

 

Printing vertically

Write a program to read a word into the variable word and print each letter of the word twice on its own line.

Example: if the user inputs "CS", the output should be:

C C
S S

 

Splitting strings

Useful functions from the string library:

>>> import string

>>> temp= "There's four new colors in the rainbow, an old man's taking polaroids"

>>> parts1=string.split(temp)

>>> parts2=string.split(temp,",")

>>> temp1=string.join(parts1)

>>> temp2=string.join(parts2)

Is temp1==temp?

What about temp2==temp?

What does the following command do?
>>> string.replace(temp, " ", ";")

CS105