2 - Programming Flashcards
What are data types? Give some examples of some:
-data types describe the different types of data being used, and defines the range of values a variable may take
-int, real, bool, char, string
in python, real numbers are called floats
Why are data types needed?
-so the computer knows what operations it can perform on it
-it allocates the necessary amount of memory to optimise the program
in python, real numbers are called floats
What is a variable?
named identifier that holds a value in memory that can change
What is a constant, and what is it used for?
-named identifier that is given a value when initialised and holds it in memory, and doesn’t change throughout the program
-used to reference known values like pi
Define declaration/initialisation:
-naming a new identifier for the first time
-then assigning it a value
In Python, both are usually done at the same time, but some languages (like VB) do it separately
What is an identifier?
a name for a variable, constant, or subroutine
Why should you give meaningful identifier names?
-meaningful identifier names describe the purpose of the variable
-makes the program easier to interpret/debug
What are the 3 programming constructs?
-sequence
-selection
-iteration
What is sequence in programming?
executing 1 instruction after another (imperative programming)
What is selection in programming?
statements that change the flow of a program based on conditions that are met (branching)
What is iteration in programming? Describe the 3 types:
repeated execution of a section of code
for - count controlled
while - condition checked at start, may never run
repeat until - condition checked at end, always runs once
The bottom 2 are condition controlled
What is nesting?
putting a statement inside another with selection/iteration
Name 3 types of arithmetic division and give their Python symbols:
-real division, just normal ÷
/
-integer division, DIV, division that returns the integer part of the result
//
-remainder division, MOD, returns remainder
%
Name the boolean operators:
NOT
AND
OR
What are data structures?
an abstract idea of how to store and access data in a computer system
Why are data structures described as abstract?
-the computer memory doesn’t actually know it is a list, it just stores it in memory as it usually would
-it just makes it easier for the programmer to read/access
What is an array?
a data structure (1 or 2 dimensional) comprised of a set number of cells containing data all of the same type
How do you access data from a 2D array?
-the first square bracket indicates the list you want to access from the 2D array
-the second square bracket indicates the item from the previously specified list
remember indexing starts from 0
What is a record?
a data structure containing a set of information about certain items
How would you make a record in python without importing anything?
make a dictionary where the key is the name of the item, and the value is all the information about the item in the form of another dictionary
record = {
"bob":{"score":102,"name":"bob name},
"john":{"score":321,"name":"john name"},
"fred":{"score":7,"name":"fred name"}
}
Using an import statement, how could you make a record in python?
if you are making more than one dataclass, always put @dataclass before it
How do you add a record to a dataclass?
make sure you give a value to every one of the arguments when adding a record
How do you access a particular value from a record in a dataclass?
Describe a dictionary:
dict = {key1: value1, key2: value2}
-values can be accessed by doing dict[key]
What is the code for making substrings?
myString[a:b]
a, start
b, end (not included)
How do you make a string in all capitals or lower case?
myString.upper() myString.lower()
How do you find a particular character or word within a string?
myString.find("a bc")
-returns integer that shows the position of the first character in the find brackets
-if it doesn’t find it, then it will return -1
How do you reverse a string?
myString[::-1]
What is another way to concatenate some variables in a print statement?
always put the f before so that it recognises the formatting needed
Functions for converting to character code and back:
ASCii to text:
chr(myAsc)
Text to ASCii:
ord(myChar)
How do you generate a random number in python?
import random num = random.randint(startRange,endRange)
What is the difference between randint and randrange?
-randint takes a random number between the start and end numbers inclusive
-randrange does not include the end number
However both are used in the same way - (random.randint(), random.randrange())
How do you use shuffle?
import random list = [1,2,3,4,5,6,7,8,9] random.shuffle(list)
DO NOT put the last line in a print statement, it doesn’t work for some reason
What is a subroutine, and how is it used?
-indented block of code used in order to execute a commonly used task
-can be called by writing its identifier name as a statement and passing the necessary parameters
What is the difference between a global and a local variable?
global is can be accessed/changed throughout the whole program, while local only exists within a certain subroutine
What are the advantages of local variables over global ones?
-easier to debug program as variable can only be accessed within its own subroutine
-more memory efficient as once the subroutine finished, all of the local variables used in it are removed from memory
Difference between a procedure and a function:
functions return a value
Functions can also return a value as a string, eg:return "num1"
This won’t print the string but assign it to the variable where the function was called
Why was the structured approach to programming developed?
to give programmers a logical structure that uses modules/subroutines to aid code interpretation/debugging
What are the advantages to using modularised programming in the structured approach of programming?
-can be reused to reduce development time
-easier to find errors in code
-can be changed without affecting the rest of the program
-subroutines can be developed separately by different people and combined later on
Make sure to put the first point as a whole, don’t just put “reduces development time” by itself
A programmer uses the code below in order to make a program. Explain how they have used the structured approach to programming:
-decomposed the problem into sub-problems
-solved sub-problems by using subroutines and passing the necessary parameters
What is robust and secure programming?
writing sections of code to catch errors from invalid user inputs that wouldn’t usually be expected
Types of testing data:
-valid data, within accepted bounds
-invalid/erroneous data, rejected by program
-boundary/extreme data, either side of bounds
If asked to give an example of boundary data, just give one value rather than giving both sides of the boundary
Name the different types of validation checks:
range check - for numbers
length check - for strings
presence check - eg checking if a password has been entered a second time
format check - eg checking if your date of birth is in the form DDMMYYYY
type check - eg checking if a number is an integer
Name 2 types of errors:
-syntax (misspelt code, eg missing punctuation/letters)
-logic (program can run but not as intended, eg bool value is true rather than false)
A program has the statement:if distance <= 5:
How many possible values could the result of this comparison have?
2 (either distance is less than/equal to 5, or it is greater than 5)
boolean
