We covered the following examples on the board:
Return the last 2 characters of a string:
def last2(s):
return s[-2:]
Add up the cubes of the numbers from 1 to n:
def sum_cubes(n):
counter = 1
answer = 0
while counter <= n:
answer = answer + counter**3
counter = counter + 1
return answer
Return n duplicate copies of a string:
def dups(s,n):
counter = 1
answer = ''
while counter <= n:
answer = answer + s
counter = counter + 1
return answer
Count how many times a character appears in a string:
def ccount(s,c):
counter = 0 # note that this starts at 0 instead of 1
answer = 0
while counter < len(s): # note that this is a little
different
if s[counter] == c:
answer =
answer + 1
counter = counter + 1
return answer
Homework problems: Create a .py file with all of the functions below, plus your test cases, and submit to the homework server.
1. strcount(s,q). returns how many times the string q appears in the string s. Examples (look at these carefully and undrstand them before starting):
2. div23(n): Add up the numbers (from 1 to n) that are evenly devisible by 2 or evenly divisibly by 3 (or both). Examples:
3. findchar(s,c): returns the position of the first occurrence of the character c in the string s (c will aways be a single character). Returns -1 if not found. Examples:
4. findstringrev(s,q): returns the position of the last occurrence of the string q in the string s. Returns -1 if not found. Examples: