Difference between revisions of "CSC111 While Loop Exercises"
(→Loop Exercises) |
|||
| Line 70: | Line 70: | ||
<br /> | <br /> | ||
<onlydft> | <onlydft> | ||
| − | ==Solution | + | ==Solution Programs== |
<source lang="python"> | <source lang="python"> | ||
def exo1( ): | def exo1( ): | ||
| Line 79: | Line 79: | ||
return ans | return ans | ||
| + | def exo1b(): | ||
| + | while True: | ||
| + | try: | ||
| + | x = eval( input( "Enter a number greater than 0: " ) ) | ||
| + | if x > 0: | ||
| + | return x | ||
| + | print( "Invalid number.", x, "is negative." ) | ||
| + | except ( NameError, SyntaxError ): | ||
| + | print( "Invalid input. Try again!" ) | ||
| + | |||
def exo2( ): | def exo2( ): | ||
ans = input( "Should we continue (Yes/No)? " ) | ans = input( "Should we continue (Yes/No)? " ) | ||
| Line 110: | Line 120: | ||
print( "Key not found" ) | print( "Key not found" ) | ||
| + | def exo3c( fileName, key ): | ||
| + | """this version of the function is more robust and will not crash if the | ||
| + | file does not exist""" | ||
| + | try: | ||
| + | file = open( fileName, 'r' ) | ||
| + | except IOError: | ||
| + | print( fileName, "does not exist" ) | ||
| + | return False | ||
| + | |||
| + | for line in file: | ||
| + | if line.find( key ) != -1: | ||
| + | print( "found", key, "in line:\n>>>", line ) | ||
| + | file.close() | ||
| + | return True | ||
| + | |||
| + | print( key, "not found..." ) | ||
| + | file.close() | ||
| + | return False | ||
| + | |||
| + | |||
def exo4(): | def exo4(): | ||
sum = 0 | sum = 0 | ||
Revision as of 10:09, 15 November 2011
--D. Thiebaut 09:43, 10 November 2011 (EST)
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 the number until it is valid. The function will return the number.
- 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 a particular string. The function receives the name of the file, and the string.
- 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 to be correct, 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.
def Exercise5():
P1 = 0
P2 = 0
while abs( P1 - P2 ) < 3:
play = input( "\n\nEnter Player1 Player2 choices: " ).upper()
while not ( play in ["SS", "RR", "PP", "SR",
"SP", "RS", "RP", "PS", "PR" ] ):
play = input( "Invalid! Try again: " ).upper()
if play in [ "SP", "PR" ]: P1 += 1
if play in [ "PS", "RP" ]: P2 += 1
print( "Player 1: ", P1, "points -- Player 2: ", P2, "points" )
if P1 > P2:
print( "Player 1 wins!" )
else:
print( "Player 2 wins!" )
- 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
