Intro To Python

Question 1

What is an algorithm?

Answer 1

A step by step list of instructions that if followed exactly will solve the problem under consideration

Question 2

What is the goal in computer science?

Answer 2

Is to take a problem & develop an algorithm that can serve as a general solution

Question 3

What is the most important skill for a computer scientist?

Answer 3

To be able to solve problems

Question 4

True or false. High-level languages are easier to program in

Answer 4

True

They take less time to write

They are shorter and easier to read

They are more likely to be correct

They are portable = can run on all different kinds of computers

Question 5

Source code is another name for what?

Answer 5

The instructions in a program, stored in a file

Question 6

Python is a high-level language, but must be interpreted into machine code called “_______” before it can be executed

Answer 6

Binary

Question 7

It is high-level if the program must be “__________” before it can run

It is low-level if the computer can execute it w/out “_________ __________”

Answer 7

Processed

Additional processing

Question 8

What is the difference between compilers and interpreters?

Answer 8

Compilers:
- take the entire source code & produce object code
Ex. Translating an entire book

Interpreters:
- execute the code line by line
Ex. Translating a line at a time in a book

Question 9

Computing science is the study of “__________”

Answer 9

Algorithms

Question 10

What is a programming language?

Answer 10

Provide a set of instructions & syntax rules for writing code that can implement algorithms to perform specific tasks or problems

Question 11

What is the role of the python interpreter?

Translation process?

Computer execution?

Answer 11

Source code —> python interpreter —> output/results

Translation process:
- transforms code into language the computer understands

Computer execution:
- translated code —> sent to computer for execution

Question 12

What are “code blocks” in python?

Answer 12

Sections of code that tell the computer to do something specific

Can include loops, functions, and if statements etc…

Question 13

Need “____” to run python code

This is like a “_______” write down what is made & follow instructions step by step

Answer 13

IDE (integrated development environment)
**NOTE: in CMPUT 101 we use IDLE (integrated development and learning environment)

Recipe

Question 14

Python code is executed from “_____” to “_______”

Answer 14

Top to bottom

Question 15

“Hello world” is what?

Answer 15

A string

Can use single or double quotations

Question 16

How do you concatenate (join) strings together in python?

Answer 16

Do this by using the “+” operator

Ex. “Hello” +” “ + “World”

Question 17

Who or what typically finds syntax errors?

Answer 17

The compiler / interpreter

Question 18

What is a syntax error?

Give an example…

Answer 18

Syntax refers to the structure of a program and the rules about that structure

Ex. Forgetting a colon at the end of a statement where one is required

Question 19

What is a runtime error?

Answer 19

Called this because the error does not appear until you run the program

Rare in the simple programs seen in the first few chapters

Ex. Attempting to divide by zero

Question 20

What typically finds runtime errors?

Answer 20

The interpreter

If an instruction is illegal to perform at that point in the execution

The interpreter will stop with a message describing the exception

Question 21

What is a semantic error?

Give an example

Answer 21

If there is one in your program it will run successfully in the sense that there is no error messages

HOWEVER the problem is that your program you wrote is not the program you wanted to write

The program or ‘sementics’ is wrong

Ex. Forgetting to divide by 100 when printing a percentage amount
- will give a wrong answer because the programmer implemented the solution incorrectly

Question 22

Who or what typically finds semantic errors?

Answer 22

The programmer

You must fully understand the problem so that you can tell if your program properly solves it

Question 23

What is the difference between programming and debugging?

Answer 23

Programming is the process of writing the source code

Debugging is the process of finding and correcting all the errors w/in the program until it is correct

Question 24

Programming languages are “______” languages that have been designed to express computations

Answer 24

Formal

Question 25

Why is indentation so important in python?

Answer 25

Relies on this to *group statements together” Code bocks are defined by their level of indentation Each indentation must be **consistent** throughout the code block

Question 26

What does the input() function do?

Answer 26

Prompts user to input something in the shell

Question 27

What are comments?

Answer 27

Lines that are ignored by the computer Good for explaining and keeping track of different parts of code

Question 28

How do you assign variables in python?

Answer 28

With the operator “=“ Ex. course = 101

Question 29

True or false. You can have spaces in variable naming

Answer 29

False Cannot have space, must be one unit INSTEAD we can use __ (underscores) Ex. “user_name”

Question 30

True or false. You can’t start a variable name with a number

Answer 30

True You CAN use numbers, just cannot start it with one Ex. “user_name1” = good VS Ex. “1user_name” = bad

Question 31

Strings and numbers CANNOT be directly mixed What does this mean?

Answer 31

Ex. Num = 5 Numstr = “5” Num + numstr Traceback error unsupported operand type for +: ‘isn’t’ and ‘str’

Question 32

The functions (int, float and str) are called “_____” conversion functions

Answer 32

Type

Question 33

What value is printed when the following statement executes? print( int(53.785) )

Answer 33

53 **NOTE: this does not round to the closest integer**

Question 34

What is printed when the following statement executes? day = “Thursday” day = 32.5 day = 19 print (day)

Answer 34

19 The variable day will contain the **last value** assigned to it when it is printed

Question 35

True or false. You cannot have an illegal character such as “&” or “+” or “$” when naming variable

Answer 35

True Ex. more$ = 1000000 Incorrect ^^^ CANNOT have the “$” in there

Question 36

What is formatted output in python?

Answer 36

Allows you to create a **custom string** by *combining texts and values* Given the variables: num = 101 name = 'Mark' print('My number is: {}, and my name is {}'.format(num,name)) print('My number is: {one}, and my name is:{two}'.format(one=num,two=name)

Question 37

What are operators?

Answer 37

Special tokens that represent computations like addition, multiplication and division Ex. +, *, /

Question 38

What does the operator “//“ do?

Answer 38

Called integer division It always truncates its result down to the NEXT *smallest integer* Ex. print(18 // 4) Gives the integer 4 NOT the floating point 4.5

Question 39

What is printed when the following statements execute? n= input(“Please enter your age: “) # user types in 18 print ( type (n) )

Answer 39

Classified and read as a string **NOTE: all *input* from users is read in as a string**