Demo Lecture Part 1 Flashcards
Writing our first program Writing Comments, Variables and data strutures, User inputs, Conditions, Loops
break keyword
gives us the ability to exit out of loops whenever we want
how do you create an infinite loop?
while(True):
what is a boolean value?
True or False
what is an int data type?
integer: positive or negative whole number and zero
what is a float data type?
a decimal
what is a string data type?
a sequence of characters “abc123”
what is a list data type?
an ordered sequence of values of other data types [1, 2, 3]
what is a dictionary data type?
an unordered collection of key: value pairs eg {“firstname”: “Colt”, “lastname”: “Steele”}
string formatting expression using .format and variables
1 define variables
2 print string
3 print string, close with quotes, then .format in round brackets listing variables in order
first_name = “Prerna”
country = “India”
print(“My name is {}. I stay in {}.”.format(first_name,country))
string formatting with f strings
1 define variables
2 f’string’
3 variables go in curly brackets
can you reassign the same variable to different values?
yes. python will use the last one you wrote
what are the python naming restrictions? are variables case-sensitive?
must start with an underscore or letter. rest of the string can be letters, underscores, or numbers. cannot begin a variable with a number. variables ARE case-sensitive
how do you write a multi-line comment?
three double quotationcan s
how can we capture user input? what data type does it expect?
input(“text for input request).
built-in function that will store user input into a variable. expects a string, so any other type of input must be typecast to the correct data type
difference between spacing:
print(“Prerna”+”Gupta”)
print(“Prerna”,”Gupta”)
+ > no space
, > space by default
how can you get help with a keyword?
print(help(“keyword”))
False
opposite of true, truth value 0
None
None is an instance of the NoneType object type. While new NoneType objects cannot be generated, None can be assigned to any variable.
True
opposite of false, truth value 1
and
A logical operator.both things on either side of and must be true for the entire statement to be true
as
creates an alias
assert
for debugging
async
async” defines a coroutine
await
await” suspends or yields execution to another coroutine from within a coroutine.
class keyword
To define a class
continue
loop control statement.
the code inside the loop following the continue statement will be skipped for the current iteration and the next iteration of the loop will begin.
def
for defining a function
del
To delete an object
elif
or else, if. (condition)
else
if all of the above conditions are not true, do this
except
Used with exceptions, what to do when an exception occurs
finally
Used with exceptions, a block of code that will be executed no matter if there is an exception or not
for
“applying to the following”
from
To import specific parts of a module
global
To declare a global variable
if
in the case that (followed by a condition)
import
To import a module
in
To check if a value is present in a list, tuple, etc.
is
To test if two variables are equal
lambda
To create an anonymous function(one that does not have a name), takes any number of arguments but limited to only ONE expression
nonlocal
To declare a non-local variable
not keyword
A logical operator.The return value will be True if the statement(s) are not True , otherwise it will return False .
or keyword
A logical operator.one or both of the epressions must be true for the statement to be true.
pass keyword
When the user does not know what code to write, So user simply places a pass at that line. Sometimes, the pass is used when the user doesn’t want any code to execute. So users can simply place a pass where empty code is not allowed, like in loops, function definitions, class definitions, or in if statements.
raise keyword
To raise an exception
return keyword - what does it do?
To exit a function and return a value
try keyword
To make a try…except statement
while keyword
To create a while loop
with keyword
used in exception handling to make the code more readable. It simplifies the management of common resources like file streams.
yield keyword
To end a function, returns a generator
how do you get the data type of a variable or other piece of data?
type(data)
+ operator
adds two operands
(-) operator
subtracts two operands
(*) operator
multiplies two operands
/ operator
division. divides first operand by the second. returns a float
// operator
floor division:
divides first operand by the second, returns greatest integer less than or equal to dividend (number being divided)
eg 10/3=3 because 3*3=9, which is the closest whole number to 10. essentially gives the greatest whole number of times the divisor can go into the dividend, gives no remainder.
% operator
modulus:
returns REMAINDER when first operand is divided by the second
** operator
to the power of. first # raised to the power of second #
idx
abbreviation for index
can you define a functionw ithin a function? what’s it called?
yes
nested function
how do you produce numbers corresponding to list elements?
enumerate function:
enumerate(iterable, start=int)
what is a range? and what is the syntax?
a slice of a number line
(x=starting number, y=number AFTER ending number, z=increments)
what is a factorial?
the product of all positive integers less than or equal to a given positive integer and denoted by that integer and an exclamation point. Thus, factorial seven is written 7!, meaning 1 × 2 × 3 × 4 × 5 × 6 × 7.
