Discussion - Friday, 2/18/2011
Topics: Format strings, escape sequences, loops
Complete the exercises at the end of this document!
Controlling the appearance of output in print statements
Format strings for different types:
%f -- used for floating point numbers
%e and %E -- used for floating point numbers in exponential form
%d -- used for integers
%s -- used for strings
Example with floating point numbers:
print "%.2f and %.4f are my favorite numbers!" % (3.14159, 2.71835)
3.14 and 2.7184 are my favorite numbers!
Note: For the two values in the above example, we are printing:
- 2 digits after the decimal point for the first number (%.2f), and
- 4 digits (%.4f) after the decimal point in the second number.
Example with integers and strings:
print '%s is %d years old' % ('Elvis', 25)
Elvis is 25 years old
while <some condition>:
number = 10
while number >= 7:
number = number - 1
What is the output??
for i in sequence:
Note: Execute the body of the loop once for each value of i in the sequence.
for i in [1, 2, 3]:
What is the output?
sum = 0
for i in range(1, 5):
sum = sum + i
print 'The sum is %d.' % sum
Use escape sequences inside quotes in print statements: these 2 character sequences start with a backslash.
\t -- tab
\n -- carriage return
\\ -- display a backslash
1. Write a program that uses a for loop to compute the sum of the even integers from 12 to 100.
2. Read two numbers from the user, and print their sum. Note that you must use a format string to produce the output.
First number? 10
Second number? 12
The sum is 22.
3. Use a while loop to print 99, 96, 93, ..., 3 in this order to the screen, one number per line.
4. Write a function make10 that, given two ints a and b, prints True if one of them is 10 or if their sum is 10.
def make10(a, b):
# finish the function definition