Chapters 2-4: Functions and Conditionals

Question 1

Boolean Expression

Answer 1

Expression either true or false.

Question 2

=

Answer 2

Assignment operator

Question 3

==

Answer 3

Comparison operator - equals

Question 4

greater than, =/greater than, is/is not operators

Answer 4

> , >=, is, is not

Question 5

elif

Answer 5

Used after the if, short for else if. can be as many as you want in a block, or none. Used same as if, ie if …..:

Question 6

else

Answer 6

used at and of the block (if needed) - sets what happens if no conditions (if and elif) are met). used by itself, ie else:

Question 7

nested conditional

Answer 7

when a conditional eg ‘else:’ has 2 sub braches, eg an if and an else

Question 8

try/except

Answer 8

try: some code. if there is an error (eg cant float an input because it’s words), move on to the except:. No exception? skip the except:.

Question 9

Guardian pattern

Answer 9

A logical expression guarding against a runtime error, using the fact logical expressions are evaluated left to right. eg [something] and x!=0 and (3/x)>2. x!=0 guards against runtime error caused if x=0, as 3 cant be divided by it.

Question 10

what error message tells you about error locaction

Answer 10

tells you where python detected the error, not necessarily where it is. true error may be earlier in code.

Question 11

Function

Answer 11

named sequence of statements that performs a computation, eg type()

Question 12

Argument

Answer 12

the expression in the brackets of a function, ie the the expression the function “takes” before it “return”s a “value”

Question 13

max()/min()

Answer 13

Functions which return the largest/smallest character/number in a string/comma’d list

Question 14

len()

Answer 14

Function which returns the number of characters in a string

Question 15

import math

Answer 15

Imports the “math” module. Can then be used, eg assign radians=0.7, height=math.sin(radians) (prefix functions with math.)

Question 16

import random

Answer 16

Imports the “random” module, allows the generation of pseudorandom (deterministic but you cant really tell) with various random.functions

Question 17

x=random.random()

Answer 17

Assigns x as random number between 0.0 and 1.0 (inclusive of 0.0 but not 1.0)

Question 18

random.randint(1, 10)

Answer 18

Returns a pseudorandom number between 1 and 10 inclusive.

Question 19

x=[1, 3, 5, 7]

Answer 19

Assigns x as a sequence, from which individual numbers can be chosen.

Question 20

random.choice(x)

Answer 20

Returns a pseudorandom choice from a pre-assigned sequence, x.

Question 21

def

Answer 21

defines a function, eg def print_lyrics(): // [tab]print(‘xxxxx’). 1st line is head, ends with “:”. Rest is the body, indented.

Question 22

def x(y)
z(y)
z(y)

Answer 22

defines a function with (a) parameter(s). Python learns to do the same regardless of parameter if the y is the same in x(y) and z(y)

Question 23

fruitful vs void function

Answer 23

function which returns a ‘worked-out’ result eg input() or math.sqrt(), vs a function which performs a task eg print()

Question 24

return

Answer 24

used in the body of a function definition, to return the result of a fruitful function, eg def addtwo(a, b)//[tab]added=a+b//[tab]return added. Without final line, python adds the parameters but the result isnt reported, so it’s pointless.

Question 25

None

Answer 25

A type of value, just like str or int, which means it is the result of a void function, or a fruitful function where the output has not been returned.

Question 26

round(x, n)

Answer 26

Function, rouund a number, x, to n decimal places.

Question 27

quit()

Answer 27

quit python/python environment

Question 28

user_input=input(‘Type something!\n’)

Answer 28

assigns user_input variable with the vavlue user enters

Question 29

Semantic error

Answer 29

The situation in which a program executes but does not produce the results that were intended. No error message, just wrong result.

Question 30

Syntactic error

Answer 30

Error on syntax, ie grammar, of the command which means the interpreter cannot intrpret it. Leads to error message.

Question 31

Logic error

Answer 31

An error in logic, often due to order of statements being wrong, or how the relate to one another.

Question 32

Variable

Answer 32

A name you can assign a value, e.g. a=45, message=’hey man’. ‘x’ not needed for variables, but is for value. Python interprets these IDENTICALLY to their value unless changing the value with variable=something new. Case sensitive!

Question 33

int()/float()/str()

Answer 33

returns argument as given type. convert with x=int(‘x’) etc

Question 34

**

Answer 34

exponentiation, eg 5**2 = 5^2 = 25. alongside

Question 35

//

Answer 35

/ but truncates result to an interger, i.e. rounds down to nearest interger. 5.9//2=2.0

Question 36

%

Answer 36

modulus, gives the remainder not the quotient. 7//3=2, 7%3=1. v. useful, used in clever ways.