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Tutorial B1

9 important questions on Tutorial B1

Bij string (for i in range -> for .... in ...)

text = 'my textual data'
for ch in text:
print ch

Bij string (for i in range(len(text)): -> bruikbaar/nuttig

for i in range(len(text)):
print 'character at position', i, ':', text[i]

character at position 0 : m
character at position 1 : y
character at position 2 :
character at position 3 : t
character at position 4 : e
character at position 5 : x
character at position 6 : t
character at position 7 : u
character at position 8 : a
character at position 9 : l
character at position 10 :
character at position 11 : d
character at position 12 : a
character at position 13 : t
character at position 14 : a

Integer values of charachters - ord met type Int en Chr met type String

waar opgeslagen, te vinden met ord('a')

>>> ord('a')
97
>>> chr(97)'a'

Controleren van de count bound loop door (2)

range
opsommen van elementen uit een reeks

An example of the former is counting how many times a given letter occurs in a given string: (loop template)

def count (s, letter):
    s = 'Analogous to str method count'
    result = 0
    for ch in s:
        if ch == letter:
            result = result + 1
    return result

An example of the latter is adding(sum) a series of numbers entered by the user:

n = raw_input('how many numbers to add? ')
n = int(n)
sum = 0
for i in range(n):
    num = raw_input('add a number: ')
    num = int(num)
    sum += num   # shorthand for sum = sum + num
print 'the total is', sum

A “sentinel bound loop”

is a loop where the decision to repeat or stop depends on a special value for some variable: the “sentinel” , WHILE LOOP

A “data bound loop”

is a loop that stops as soon as some computed value (data) fulfills a particular condition. WHILE LOOP

This function multiplies a variable power by base until the power is larger than a given threshold (while loop)

def find_power (base, threshold):
    'Find first power of base above threshold'
    power = 1
    exponent = 0
    while power <= threshold:
        power *= base   # power = power * base
        exponent += 1
    return exponent, power

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Python

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Tutorial B1

9 important questions on Tutorial B1

Bij string (for i in range -> for .... in ...)

Bij string (for i in range(len(text)): -> bruikbaar/nuttig

Integer values of charachters - ord met type Int en Chr met type String

Controleren van de count bound loop door (2)

An example of the former is counting how many times a given letter occurs in a given string: (loop template)

An example of the latter is adding(sum) a series of numbers entered by the user:

A “sentinel bound loop”

A “data bound loop”

This function multiplies a variable power by base until the power is larger than a given threshold (while loop)

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