Module 3 Flashcards
What data type is the following?
(10, 20)
Tuple
What is the result of this comparison?
2 == 2.0
True
What is the difference between these two operators?
“=“
“==“
= is the assignment operator. It assigns a value to a variable
== is the equality operator. It compares two values
What is this operator or and what does it do?
!=
The not equal operator. This checks whether two values or expressions are not equal to each other
It is a binary operator.
Returns a Boolean value
What is this operator?
<=
Less than or equal to
What is this operator? And what does it do?
> =
Greater than or equal to
It is a binary operator
It compares values on either side of it
It has left side binding
As far as priority goes, where do the greater than, less than, greater than or equal to, and less than or equal to operators sit in the spectrum?
They are below binary addition subtraction operators and above the equality and not equal operators
What is a group of if-elif-else statements called?
A cascade
What does the max() function do?
Finds the largest number out of multiple arguments or an iterable
List the comparison operators
== equal
!= not equal
> Greater than
< Less than
>= greater than or equal to
<= less than or equal to
Are comparison operators binary?
Yes
Do uppercase letters have a higher ASCII value than lowercase letters?
No
In fact, lowercase letters have a higher value than their uppercase counterparts
A number corresponding to a character is called a:
Codepoint
can len() return the value of an int or a float?
No
What is the output of this code?
x = 10
if x == 10:
print(x == 10)
if x > 5:
print(x > 5)
if x < 10:
print(x < 10)
else:
print(“else”)
True
True
else
all If statements are evaluated
The final code block is an If/Else statement. Since the If fails, then the Else is triggered
What is the output of the following snippet?
x = 1
y = 1.0
z = “1”
if x == y:
print(“one”)
if y == int(z):
print(“two”)
elif x == y:
print(“three”)
else:
print(“four”)
one
two
Both if statements are evaluated
Since the second if belongs to an if/elif/else block, once the first if is successfully evaluated the elif and the else are skipped
a “while” statement repeats the execution of the code inside it as long as the condition evaluates to _________
True
An instruction or set of instructions executed inside the while loop is called
the loop’s body
True or False?
If the “while” condition is False when it is evaluated the first time then the loop’s body is executed at least once
False
If the “while” condition is false when it is first evaluated, then the loop’s body is never executed
What is another name for an Infinite Loop?
An Endless Loop
What is the “for” loop designed for?
To browse large collections of data
Like the results of a database query
i.e.
new_row = []
for row in results:
order_num = row[1]
new_row.append(order_num)
any variable after the “for” keyword is the __________ variable
control
What does the control variable of a “for” loop do?
it counts the loop’s turns automatically
Is the range() function inclusive
No
It is exclusive.
So, range(100) will give you all values from 0 to 99
How many arguments can the range() function take?
3
If 2 arguments are provided, the first positional argument denotes the starting value, the second parameter is the ending value
So,
for i in range(2,8): print(i)
will print these integers to the console: 2,3,4,5,6,7
if 3 arguments are provided, the third argument is the increment or “step”
for i in range(2, 8, 3): print(i)
will print these integers to the console:
2,5
does the range() function accept floats as an argument?
no. Only integers. And it produces only integers
The range() function only accepts _________ as arguments
integers
What is the printout of the following code snippet?
for i in range(2, 8, 3):
print(“here is:”, i)
here is 2
here is 5
What does the “break” keyword do inside a loop?
exits the loop immediately
What does the “continue” keyword do inside a loop?
it behaves as if the loop execution was finished, and starts the loop over from wherever the continue keyword is accessed
So
for in in range(2,12, 3):
if i == 5:
continue
print(i)
will print the following to the console:
2
8
11
(Skipping 5)
when is a loop’s “else” branch executed?
every time - whether the while (or “for”) loop’s body is executed or not
Unless the loop is exited by the “break” keyword
What does the following code snippet print to the console?
i = 111
for i in range(2, 1):
print(i)
else:
print(“else:”, i)
111
the for loop’s body is never executed, and (it doesn’t change the i variable’s value) so the else branch is executed and the value of i is printed to the console
- unless the loop is broken – as in, unless the loop is terminated by break
What is a connection of conditions called?
A conjunction
What is a logical operator that is a unary operator that performs logical negation?
not
Which logical operator is known as logical negation?
not
Which logical operator is known as logical conjunction?
and
Which logical operator is known as logical disjunction?
or
When is a loop’s else branch NOT executed?
If the loop’s execution is broken by the “break” keyword
Describe how strings are compared by comparison operators
They are compared lexicographically
Letters increase in value as they continue in the alphabet
So
print(“a” < “b”) == True
And capital letters have a lower value than their lowercase counterparts
So
print(“A” < “a”) == True
print(“a” < “b”) # True
print(“A” < “a”) # True
print(“apple” < “banana”) # True
print(“apple” < “application”) # True
print(“apple” == “apple”) # True
print(“Apple” < “apple”) # True
What is the printout of the following code snippet?
print(“apple” < “application”)
True
The strings are the same up until the letter “e” in Apple
“e” has a lower lexicographic value than “I” so “apple” evaluates to less than “application”
What is the result of this code snippet?
print( “this is “ + “ my test Exam “.lstrip() + “woot”)
this is my test Exam woot
lstrip() only strips leading blank spaces from a string
How to remove all items from a dictionary?
Use the clear() method
What will this code snippet return? Why?
alist = [3, 4, 5]
print( “this one”,alist[-2:8])
this one [4,5]
String slicing doesn’t care if the end index is out of range for the string. It will slice as much of the string as it can
what is the logical conjunction operator in Python?
and
When does the logical conjunction operator (and) evaluate to True?
When both operands are True
When does the logical disjunction operator (or) evaluate to True?
When at least one of the operands are True
How does the logical negation operator work?
It is a unary operator, so it only needs one operand.
If the operand is True, then it makes it False
If the operand is False, then it makes it True
What is the result of this code snippet?
var = 17
var_right = var»_space; 1
print(var_right)
8
the right shift operator halves the left operand by the amount of the right operand
It is, essentially, working as integer division.
in this case 17/2 = 8.5, rounded down (floor) = 8
Okay, smart guy, what is the result of this code snippet?
What is the result of this code snippet?
var = 18
var_right = var»_space; 3
print(var_right)
2
18 / 2 = 9
9 / 2 = 4.5 (floor = 4)
4 / 2 = 2
What is the output of this code snippet?
x = 1
y = 0
z = ((x == y) and (x == y)) or not(x == y)
print(not(z))
False
Left Side Operand:
( ( x == y ) and ( x == y ) ) —> False
logical and only evaluates to True if both operands evaluate to True
Since both operands in this case are False, then the logical and evaluates to False
Right Side Operand:
not( x == y) —> True
Logical negation always changes the Truthiness of its operand. So, since x == y is False, then the logical negation changes it to True
or
The logical or evoluates to True, so long as one of its operands is True
So, since the left side operands is False and the right side operand is True, then the logical or evaluates to True
So….
z == True
And finally, the print applies a logical negation to var z (which is True), so the result is False
How to calculate the binary value of a number?
repeatedly divide the number by 2 and note the remainders, then write the remainders in reverse order
Ex:
What is 10 in binary?
10 / 2 = 5 remainder —-> 0
5 / 2 = 2 remainder ——> 1
2 / 2 = 1 remainder ——> 0
1 / 2 = 0 remainder ——> 1
Reversing the order of remainders = 1010 which is the binary value of 10
What is the result of this code?
x = 4
y = 1
a = x & y
print( a )
0
x = 4
4 = 100 when converted to binary
4 / 2 = 2 rem 0
2 / 2 = 1 rem 0
1 / 2 = 0 rem 1
reverse the remainders and you get 100 is the binary of 4
y = 1
1 = 1 when converted to binary (0 = 0 when converted to binary)
Bitwise logical conjunction requires two 1s to make a 1, so a 0 and a 1 makes a 0
So…
100 & 001 = 000
or look at it this way:
100
001
—–
000
So…
x & y = 0
What is this operator? And what does it do?
&
bitwise conjunction
It requires two 1s to make a 1, so a 1 and a 0 = 0
