CSC111 Exercises on Loops

Loop Exercises

Exercise 1

Write a function that asks the user to enter a number that is greater than 0. The function will keep on asking the user for a number until the number is correct. The function will return the number.

Example:

Please enter a number greater than 0: -1
Invalid number.
Please enter a number greater than 0: -10
Invalid number.
Please enter a number greater than 0: 0
Invalid number.
Please enter a number greater than 0: 10
(the function then returns 10 to the code section where it was called)

Exercise 2

Write a function that asks the user to respond by 'Y', 'y', 'yes', 'YES' or 'N', 'n', 'no', 'NO'. The function keeps on asking until the user enters the correct information. The function will return True if the user entered Yes, and False otherwise.

Exercise 3

Write a function that reads lines from a file until it finds a line that contains the string "<<<END>>>". The function receives the name of the file and returns the lines read.

Exercise 4

Pi can be computed by adding the following terms (http://en.wikipedia.org/wiki/Pi):

How many terms does it take to get the first 3 digits, 3.14?

Exercise 5

Write a program that reads 2 characters from either the keyboard or a file. The characters are either PP, PR, PS, RP, RR, RS, SP, SR, SS. They correspond to the selections made by 2 players playing the game of rock-paper-scissors.

Make the program accept inputs until one player's score is more than 3 points ahead of the other.

Exercise 6

Replace the for-loops by while-loops in the following code

for c1 in 'ab':
     for c2 in 'abcdefghijklmnopqrstuvwxyz':
          print "111c-" + c1 + c2

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