python3python3I have posted homework 9 here.
It is due this coming Sunday at 11:59 PM.
You must make the script for this assignment executable or you will loose points.
You will find the answers to Quiz 7 here.
Let's review them.
Are there any questions before I begin?
openopen is the pathname of the file
./ex20.py /usr/bin/python3^M bad interpreter: No such file or directory
dos2unix
dos2unix FILENAME
python3python3 at the command line we are running this
binary file
python3 then executes all the Python statements in the file
# prints a friendly message
print("Hello world!")
$ python3 hello_1.py Hello world!
python3python3
chmod command
chmod 755 FILENAME
#! /usr/bin/python3
2017-06-01 67 2017-06-02 71 2017-06-03 69 ...
>>> line = "2017-06-01 67" date, temp = line.split()
2017-06-01 67 2017-06-02 71 2017-06-03 69 2017-06-04 88 2017-06-05 74 ...
count = 0
total = 0
for line in file:
count += 1
date, temp = line.split()
temp = int(temp)
total += temp
average = round(total/count)
2017-06-01 67 2017-06-02 71 2017-06-03 69 ...
set a max to the lowest possible value
for each temperature
if the temperature is greater than max
give set max to this temperature
max_date = "" min_date = ""
if temp > max:
max = temp
max_date = date
if temp < min:
min = temp
min_date = date
#! /usr/bin/python3
file = open("temps.txt", "r")
max = -100
min = 200
max_date = ""
min_date = ""
for line in file:
date, temp = line.split()
temp = int(temp)
if temp > max:
max = temp
max_date = date
if temp < min:
min = temp
min_date = date
print("Maximum:", max_date, max)
print("Minimum:", min_date, min)
$ ./temps_max_min_dates.py Maximum: 2017-06-24 89 Minimum: 2017-06-26 66
>>> for = 5
File "<stdin>", line 1
for = 5
^
SyntaxError: invalid syntax
>>> name = "Glenn"
>>> print(nme)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'nme' is not defined
$ cat get_number_1.py
#! /usr/bin/python3
number = int(input("Number: ")
$ ./get_number_1.py
File "./get_number_1.py", line 6
^
SyntaxError: unexpected EOF while parsing
>>> for i in range(5):
... num = i * 2
... print(num)
File "<stdin>", line 3
print(num)
^
IndentationError: unindent does not match any outer indentation level
average = num_1 + num_2 / 2
print ("Average:", average)
average = (num_1 + num_2) / 2
$ ./file_open.py
Filename: xxxxxx
Traceback (most recent call last):
File "./file_open.py", line 6, in <module>
file = open(filename, "r")
FileNotFoundError: [Errno 2] No such file or directory: 'xxxxxx'
$ ./file_open.py
Filename: unreadable.txt
Traceback (most recent call last):
File "./file_open.py", line 6, in <module>
file = open(filename, "r")
PermissionError: [Errno 13] Permission denied: 'unreadable.txt'
$ ./int_request.py
Integer: five
Traceback (most recent call last):
File "./int_request.py", line 5, in <module>
number = int(input("Integer: "))
ValueError: invalid literal for int() with base 10: 'five'
>>> round("five")
Traceback (most recent call last):
File "<stdin>, line 1, in <module>
TypeError: type str doesn't define __round__ method
$ ./divide_two_numbers.py
Numerator: 5
Denominator: 0
Traceback (most recent call last):
File "./divide_two_numbers.py", line 7, in <module>
result = numerator / denominator
ZeroDivisionError: division by zero
Segmentation fault: Core dumped
try/except statement ...
try:
STATEMENT
STATEMENT
...
except:
STATEMENT
STATEMENT
...
try
code block
execute normally ...
try block ...
except code block ...open to create a file ...try/except statement
$ cat open_file.py
#! /usr/bin/python3
# demonstrates using a try/except statement
# to catch exceptions encountered while
# trying to open a file
filename = input("Filename: ")
try:
file = open(filename, "r")
for line in file:
print(line.rstrip())
except:
print("Could not open file", filename)
$ ./open_file.py
Filename: xxxx
Could not open file xxxx
for looptry codeinput function to ask the user for a
number ...
>>> number = int(input("Integer: "))
Integer: 5.0
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: invalid literal for int() with base 10: '5.0'
while loop
ask the user for a value
while the value is not valid:
print an error message
ask the user for a value
return the value
try/except statement
try/except statement needs to be inside the
while loop
while loop use?False
while loop will keep running as long as the flag is
False
True
set a flag to false
while the flag is not true
ask the user for a value
try:
convert the value to an integer
set the flag to true
except:
print an error message
return the value
def get_integer():
done = False
while not done:
number = input("Integer: ")
try:
number = int(number)
done = True
except:
print(number, "cannot be converted into an integer")
return number
$ ./get_integer.py Integer: 2.0 2.0 cannot be converted into an integer Integer: 2 2
while loop runs ...while True
return statementreturn statement will be run ...return statement always causes the function to stop
def get_integer():
while True:
number = input("Integer: ")
try:
number = int(number)
return number
except:
print(number, "cannot be converted into an integer")