input
Functionif
Statementsif
-else
Statementsif
-else
Statementif
-elif
-else
Statementsfor
Loopsrange
FunctionI have posted homework 7 here.
It is NOT due this coming Sunday.
Instead it is due Sunday, March 27th.
This is to give you time to study for the midterm.
And to give me time to score it.
October 22nd.
The exam will be given in this room.
It will consist of questions like those on the quizzes along with questions asking you to write short segments of Python code.
60% of the points on this exam will consist of questions from the Weekly Graded Quizzes.
There is a link to the answers to the graded quizze on the class web page.
There will be 15 of these questions, worth 4 points each.
The other 40% of points will come from four questions that ask you to write a short segment of code.
There will be 4 of these questions worth 10 points each.
To study for the code questions you should be able to
if
/elif
/else
statement
while
loopfor
loop using range
A good way to study for the code questions is to review the Class Exercises and homework solutions.
Today's class will be a review session.
You will only be responsible for the material in the Class Notes for today's class on the exam.
If for some reason you cannot take the exam on the date mentioned above you must contact me to make alternate arrangements.
The Midterm is given on paper.
I scan each exam paper and upload the scans to Gradescope.
I score the exam on Gradescope.
You will get an email from Gradescope with your score when I am done.
The Midterm is a closed book exam.
You are not allowed to use any resource other than what is in your head, while taking the exam.
Cheating on the exam will result in a score of 0 and will be reported to the Administration.
Remember your Oath of Honesty.
To prevent cheating, certain rules will be enforced during the exam.
Remember, the Midterm and Final determine 50% of your grade.
Let's look at the answers to Quiz 5.
Today is a review session.
There will no Class Exercise or Class Quiz today.
Are there any questions before I begin?
5 6.47 True
print("Hello world!")
>>> team = "Red Sox" >>> name = "Glenn Hoffman"
>>> print("Hello") # but ignore this text Hello
VARIABLE_NAME = EXPRESSION
name = "Glenn Hoffman"
int
)float
)input
Functioninput
function gets a value from the userinput
in a script it
stops running ...
input
waits for the user to type some textinput
returns the string to
the
function call
>>> name = input("Name: ") Name: Glenn >>> name 'Glenn'
input
is always a stringint
function
>>> number = int(number) >>> type(number) <class 'int'>
Character | Operation | Description |
---|---|---|
+ | Addition | Adds two numbers |
− | Subtraction | Subtracts one number from another |
* | Multiplication | Multiplies one number by another |
/ | Division | Divides one number by another and gives the result as a decimal number |
// | Integer division | Divides one number by another and gives the result as an integer |
% | Remainder | Divides one number by another and gives the remainder |
** | Exponent | Raises a number to a power |
>>> 4 / 2 2.0 >>> 4 / 5 0.8
float
int
)
>>> 10 // 3 3
>>> 3 ** 2 9 >>> 3 ** 3 27 >>> 3 ** 4 81
>>> 17 // 5 3
>>> 17 % 5 2
** | Exponentiation |
* / // % | Multiplication, division and remainder |
+ - | Addition and subtraction |
2 + 3 * 5
>>> 2 + 3 * 5 17 >>> (2 + 3) * 5 25
Escape Character | Effect |
---|---|
\n | Causes output to be advanced to the next line |
\t | Causes output to skip over to the next horizontal tab position |
\' | Causes a single quote mark to be printed |
\" | Causes a double quote mark to be printed |
\\ | Causes a backslash character to be printed |
>>> team = "Red Sox" >>> cheer = "Let's go " + team >>> print(cheer) Let's go Red Sox
True
or False
is called a
boolean
bool
True
and
False
True
False
True
or False
depending on their
relationship
Operator | Meaning |
---|---|
> | Greater than |
< | Less than |
>= | Greater than or equal to |
<= | Less than or equal to |
== | Equal to |
!= | Not equal to |
** | Exponentiation |
* / // % | Multiplication, division and remainder |
+ - | Addition and subtraction |
> < >= <= == != | Relational Operators |
if
Statementsif
statement evaluates a boolean expressionTrue
...
if BOOLEAN_EXPRESSION:
STATEMENT
STATEMENT
...
True
if
-else
Statementsif
statement will only run the statements in the
code block ...
True
True
...True
...
False
...if
-else
statement
if BOOLEAN_EXPRESSION:
STATEMENT
STATEMENT
...
else:
STATEMENT
STATEMENT
...
True
if
clause are
executed
else
clause
are executed
if
-else
Statementif
statement and and if
-else
statement must be indented properly
if
-else
statement has two clauses
if
clauseelse
clauseif
and else
are not
exactly aligned
>>> if 4 > 3:
... print("4 is ")
... print("greater than 3")
File "<stdin>", line 3
print("greater than 3")
^
if
-elif
-else
Statementsif
-elif
-else
statement lets you
test for many conditions
if BOOLEAN_EXPRESSION_1:
STATEMENT
...
elif BOOLEAN_EXPRESSION_2:
STATEMENT
...
elif BOOLEAN_EXPRESSION_3
STATEMENT
...
...
[else:
STATEMENT
...]
else
clause means
that it is optional
elif
is short for "else if"and
operator returns True
if both its
operands are True
>>> 5 > 4 and 4 > 2 True
False
, and
returns
False
>>> 5 > 4 and 4 < 2 False
False
if both its operands are False
>>> 5 < 4 and 4 < 2 False
or
operator returns True
if either of its
operands are True
>>> 5 > 4 or 4 < 2 True
False
if both of its operands are
False
>>> 5 < 4 or 4 < 2 False
not
operator takes only one operand ...True
becomes False
>>> not 5 > 4 False
False
becomes True
>>> not 5 < 4 True
and
p | q | p and q |
---|---|---|
True |
True |
True |
True |
False |
False |
False |
True |
False |
False |
False |
False |
p | q | p or q |
---|---|---|
True |
True |
True |
True |
False |
True |
False |
True |
True |
False |
False |
False |
not
p | not p |
---|---|
True |
False |
False |
True |
** | Exponentiation |
* / // % | Multiplication, division and remainder |
+ - | Addition and subtraction |
> < >= <= == != | Relational Operators |
not | Logical NOT |
and | Logical AND |
or | Logical OR |
True
while
loop has the following format
while BOOLEAN_EXPRESSION:
STATEMENT
STATEMENT
...
True
while
loop does not become
False
for
Loopsfor
loop has the following format
for VARIABLE_NAME in LIST:
STATEMENT
STATEMENT
...
range
Functionrange
function is used to create a list of integers in a
for
loop
>>> for number in range(5): ... print(number) ... 0 1 2 3 4
>>> for number in range(1, 5): ... print(number) ... 1 2 3 4
>>> for number in range(2, 11, 2): ... print(number) ... 2 4 6 8 10
$ cat average.py # this program asks the user how many numbers # they have to enter, then performs a running # total and computes the average entries = int(input("How many entries? ")) total = 0 for entry_no in range(entries): number = int(input("number: ")) total += number average = total / entries print("Average", average) $ python3 average.py How many entries? 10 number: 10 number: 9 number: 8 number: 7 number: 6 number: 5 number: 4 number: 3 number: 2 number: 1 Average 5.5
number = number + 5
number += 5
Operator | Example | Equivalent To |
---|---|---|
+= | numb += 5 | numb = num + 5 |
-= | num -= 5 | num = num - 5 |
*= | x *= 5 | x = x * 5 |
/= | x /= 5 | x = x / 5 |
//= | x //= 5 | x = x // 5 |
%= | x %= 5 | x = x % 5 |
**= | x **= 5 | x = x ** 5 |
import
statement to bring these functions
into any Python script
str
, int
and
float
return a value
print
does not return a value
def FUNCTION_NAME([PARAMETER, ...]):
STATEMENT
STATEMENT
...
def
average = round(total/entries)