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lab45
strings-as-arrays practice

Last time, we looked at using a loop to examine each character in a string, using the square-brackets (array-lookup) to look at the i'th character. We'll practice these skills today.

YOUR TASKS:

Write a function countUpperCase, which returns the number of upper-case letters in a given string.

hint: As you write this, and you reach something which you wish was a built-in function, use the technique of wishful-thinking, and make up a helper-function to do what you want. Then you can come back later and write that, perhaps even getting some help.

Here are some test-cases for you:

# testCountUpperCase : -> None
#
def testCountUpperCase():
    print("Actual: " + str( countUpperCase( "a" ) ))
    print("Expect: " + str( 0 ))
    print("Actual: " + str( countUpperCase( "A" ) ))
    print("Expect: " + str( 1 ))
    print("Actual: " + str( countUpperCase( "Aa" ) ))
    print("Expect: " + str( 1 ))
    print("Actual: " + str( countUpperCase( "aA" ) ))
    print("Expect: " + str( 1 ))
    print("Actual: " + str( countUpperCase( "AA" ) ))
    print("Expect: " + str( 2 ))
    print("Actual: " + str( countUpperCase( "abc" ) ))
    print("Expect: " + str( 0 ))
    print("Actual: " + str( countUpperCase( "ABC" ) ))
    print("Expect: " + str( 3 ))
    print("Actual: " + str( countUpperCase( "ABC" ) ))
    print("Expect: " + str( 3 ))
    print("Actual: " + str( countUpperCase( "?AbC!@#$42 Z " ) ))
    print("Expect: " + str( 3 ))
    return None

(Optional self-challenge — not to be checked off, but you should be able to do this.)
Write a function containsChar : string, char -> Boolean which determines whether a string contains a given letter. Do not use string.find¹!

Note: There are several ways to solve this problem; I can think of three that are all reasonable; some involve a so-far variable, and some don't.

hint: Your overall answer involves a boolean. That means your so-far variable should be a boolean — something like seenItSoFar!

hint: If you want to update a boolean so-far variable, rather than something like “vowelsSoFar = vowelsSoFar + 1”, you might say something like “seenItSoFar = seenItSoFar or …”,

# testContainsChar : -> None
#
def testContainsChar():
    print("Actual: " + str( containsChar( "a", "a" ) ))
    print("Expect: " + str( True ))
    print("Actual: " + str( containsChar( "a", "b" ) ))
    print("Expect: " + str( False ))
    print("Actual: " + str( containsChar( "abcd", "a" ) ))
    print("Expect: " + str( True ))
    print("Actual: " + str( containsChar( "abcd", "b" ) ))
    print("Expect: " + str( True ))
    print("Actual: " + str( containsChar( "abcd", "d" ) ))
    print("Expect: " + str( True ))
    print("Actual: " + str( containsChar( "abcd", "x" ) ))
    print("Expect: " + str( False ))
    print("Actual: " + str( containsChar( "", "x" ) ))
    print("Expect: " + str( False ))
    print("Actual: " + str( containsChar( "Four score and seven years ago, our fathers brought forth on this continent a new nation, conceived in liberty, and dedicated to the proposition that all men are created equal.", "q" ) ))
    print("Expect: " + str( True ))
    return None
    
    
# test : -> None
#
def test():
    testCountUpperCase()
    testContainsChar()

¹The reason is that we want to develop the skills so that we could write string.find ourselves, if it hadn't been provided! ↩

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©2014, Ian Barland, Radford University
Last modified 2014.Apr.28 (Mon) Please mail any suggestions
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lab45 strings-as-arrays practice

lab45
strings-as-arrays practice