Section 1
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guess-and-check methods
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Date created
Mar 1, 2020
Cards (58)
Section 1
(50 cards)
guess-and-check methods
Let the machine guess something, check, go back, change a parameter, check again etc. until answer arrives.
While loop
Will do the same thing over and over as long as something is true.
Variable
Declarative knowledge
statements of fact
Turing showed you can compute ___
Anything using 6 primitives: move left, move right, scan, print, erase, do nothing
5 Scalar objects
int - represents integers float - represents real numbers ex 3.27 bool - represent Boolean values True and False Nonetype - special and has one value, none
Objects come as either _____ or non ________
Scalars, which can't be subdivided, or non-scalars which have internal structure out of which we can pull parts.
modulo (%) operator
returns the integer remainder of the division. dividend % divisor = remainder.
What is the difference between an Algorithm and a Program?
An algorithm is a conceptual idea, a program is a concrete instantiation of an algorithm.
Comparison operators on int and float
i>j i>=j i<j i<=j i==j i!=j
What are the two things that computers do?
Perform calculations and remember things
What are the fundamental primitives that represent data?
Objects.
input
keyword which takes your input for a string and applies it to a variable
if-else expressions
if this is true: do this if not: else
Fixed program computer
made for one purpose only
Definitions
ways of assigning names to values or creating procedues that we're going to treat as if they are primitives
stored program computer
emulates fixed program computer in one convenient machine, a sequence of instructions built out of simple arithmetic and logic
Why would you use "print" command
If you want to see something out in the shell instead of adding to computation
Elif
IF this is true, do this. But if it is false, do this other thing. if x < y and x < z print ('x is least') elif y< z: print ('y is least')
ALU
Arithmetic Logic Unit one of two parts of basic machine - does primitive operations, testing true or false statements
Static Semantics
about meaning of sentence. Answers question: is sentence valid, what does it mean. If it is correct it will pass the static semantics test, but not necessarily be "semantic" in that it is the meaning you meant for it to have.
Nested conditionals
putting an if/else statement inside an if/else statement
Compound booleans
range
a+= b is equivalent to
a = a + b
str1 = 'hello'
assigns variable "str1" with definition 'hello'
operator for int division
i//j returns quotient without remainder
break
stops execution of code at that point, and out of a loop.
For loop
known number of times it's going to run through iterations can end early via break uses a counter can rewrite a for loop using a while loop
Every object has a ____ associated with it
Type. tells programs whether they can act on it or not.
Syntax
about structure or grammar of language. Answers question: how do I construct valid sentence
a /= b is equivalent to
a = a / b
Logic operators on bools
a and b are any variable names: not a : a and b -> true if both are true a or b -> true if either or both are true
print(x)
prints just the value of the variable 'x'
branching program simply consists of ___
a test, which returns a boolean true or false. If true, has code to say what to do in that case. If false, has code to say what to do in that case.
Commands
simple expressions that can be executed directly within python
a *= b is equivalent to
a = a * b
a -= b is equivalent to
a = a - b
mysum = 0 for i in range(7,10): mysum + = i print(mysum)
24 (seven, eight, nine, added)
one = 1 two = 2 hello = "hello" print(one + two + hello)
Won't work, can't combine strings and integers.
mysum = 0 for i in range(5, 11, 2): mysum += 1
21 (5 + 7 + 9)
operator precedence order
** * / + and - executed left to right
operator for finding power of int or float
i**j
Order of boolean operations
1. Parentheses, before operating anything else. 2. not statements 3. and statements. 4. or statements
Binding variables order
if you bind x = 2, then have x = x * x x now = 4
imperative knowledge
Directions
How many calculations can a computer do in 1 second?
A billion roughly
tuple
The shell
the current workspace.
Control Unit
Two of two parts of basic machine - keeps track of what specific operation doing in ALU at each point in time.
Section 2
(8 cards)