hw03
from variables to defining functions

# your name
# ITEC109 hw03 -- see http://www.radford.edu/~itec109/2014spring-ibarland/Homeworks/hw03.html 


# We will use some string-library functions for this hw:
import string


# A helper function, for this homework:
#
# substring -- given a string, a start-index, and a stop-index,
#   return the characters from start-index up to (but not including) stop-index.
#   Indices are 0-based.
#   Examples:   substring( "radford", 3, 6) = "for"
#               substring( "radford", 0, 3) = "rad"
#
def substring(txt,start,stop):
  return txt[start:stop]

  
#############################
####   Problem#1 (6pts)  
##   Consider the following 7 lines of code/comments:

# inputs: height and diameter of a cone:
height = 10
diam = 20

rad = diam/2
baseArea = 3.14 * pow(rad,2)
# Our final answer: the volume of the cone.
1.0/3.0 * baseArea * height


## Replace the above lines with a function name `coneVolume` by filling in the blanks below;
  
# coneVolume : float, float -> float
# Given the height and diameter of a cone (in that order),
# return its volume.
#
def __________ ( ________, _______ ):
  __________________
  __________________
  return ______________
  
#### Problem 1b (0pts): At the end of your file, inside `tst` below, uncomment the tests for `coneVolume`,
# and verify that all the expected-outputs match the actual-ouputs when you run `tst()`.




##############################
#### Problem #2 (7pts)
# Convert the following lines of code with a function named `removeLead`:
  
# The input:
msg = "the leader"

leadStart = string.find( msg, "lead" )
leadEnd = leadStart + len("lead")
beginning = substring( msg, 0, leadStart )
ending =  substring( msg, leadEnd, len(msg) )
# The answer:
beginning + ending


# removeLead : string -> string
# Given a string containing the four letters "lead",
# return the same string but with [the first occurence of] those four letters removed.
# (See examples in `tst` below.)
#



  
#################################
####  Problem #3 (7pts)
# Write the following function:

#  remove2FrontBack :  string -> string
#  Given a string of length four or more,
#  return that string with the first two and last two characters removed.
# (See examples in `tst` below.)
#


  
def tst():
  print( "Problem #1:" )
  print( "Expect: " + str(1043) + " (approx)" )
  print( "Actual: " + str( coneVolume(10,20) ) )
  print( "Expect: " + str(2086) + " (approx)" )
  print( "Actual: " + str( coneVolume(20,20) ) )
  print( "Expect: " + str(4172) + " (approx)" )
  print( "Actual: " + str( coneVolume(10,40) ) )
  print( "Expect: " + str(0) )
  print( "Actual: " + str( coneVolume(0,20) ) )
  print( "Expect: " + str(0) )
  print( "Actual: " + str( coneVolume(10,0) ) )

  print( "Problem #2:" )
  print( "Expect: " + "the er" )
  print( "Actual: " + removeLead("the leader") )
  print( "Expect: " + "Anyone can " )
  print( "Actual: " + removeLead("Anyone can lead") )
  print( "Expect: " + "" )
  print( "Actual: " + removeLead("lead") )
  
  print( "Problem #3:" )
  print( "Expect: " + "he" )
  print( "Actual: " + remove2FrontBack( "behead" ) )
  print( "Expect: " + "fore and aft" )
  print( "Actual: " + remove2FrontBack( "before and after" ) )
  print( "Expect: " + "x" )
  print( "Actual: " + remove2FrontBack( "vwxyz" ) )
  print( "Expect: " + "" )
  print( "Actual: " + remove2FrontBack( "wxyz" ) )