Question

Python Please.

a)Let a program store the result of applying the eval function to the first command-line argument. Print out the resulting object and its type. Run the program with different input: an integer, a real number, a list, and a tuple. (On Unix systems you need to surround the tuple expressions in quotes on the command line to avoid error message from the Unix shell.) Try the string "this is a string" as a commandline argument. Why does this string cause problems and what is the remedy?

b) Prompt the user for input to a formula. Consider the simplest program for evaluting the formula y(t) = v0t− 0.5gt2 [V(base 0)t - 0.5gt(square)]. : v0 = 3; g = 9.81; t = 0.6 y = v0*t - 0.5*g*t**2 print y Modify this code so that the program asks the user questions t=? and v0=?, and then gets t and v0 from the user’s input through the keyboard.

c)Modify the program listed in b) such that v0 and t are read from the command line.

d)Extend that program with exception handling such that missing command-line arguments are detected. In the except IndexError block, use the raw_input function to ask the user for missing input data. e)Test if the t value read in the program from Exercise 4.7 lies between 0 and 2v0/g. If not, print a message and abort execution.

e)Instead of printing an error message and aborting the program explicitly, raise a ValueError exception in the if test on legal t values in the program from d) Include the legal interval for t in the exception message.

f)A car driver, driving at velocity v0, suddenly puts on the brake. What braking distance d is needed to stop the car? One can derive, from basic physics, that d= 1/2 Vo2/µg [formula in english : d= 1 by 2 multiplied V(base zero)- squared divided by (/)µg] Make a program for computing d in (b) when the initial car velocity v0 and the friction coefficient µ are given on the command line. Run the program for two cases: v0 = 120 and v0 = 50 km/h, both with µ = 0.3 (µ is dimensionless). (Remember to convert the velocity from km/h to m/s before inserting the value in the formula!)

Answer 1

a)

i 2 3 import sys a=sys.argv[1] #getting first command line as input try: print(eval(a)) #print the result of command line arguement after evaluation print(type (eval(a))) #printing type of result except (NameError, SyntaxError): #execption handling for strings as commandline, print(a) print(type(a)) 6

Sample output:

$python problem.py 6 6 <type 'int'> rint (type (eval(a))) [anonymus@parrot]-[-/Desktop/HomeworkLib Error $python problem.py -45 -45 mint type a.) <type 'int'> (anonymus@parrot]-[-/Desktop/HomeworkLib) $python problem.py -45.4 -45.4 <type 'float'> (anonymus@parrot -[-/Desktop/HomeworkLib. - $python problem.py "[1,2,3,4]" [1, 2, 3, 4] <type 'list'> (anonymus@parrot]-[-/Desktop/HomeworkLib) $python problem.py "(3,4,3)" (3, 4, 3) <type 'tuple'> (anonymus@parrot]-[-/Desktop/HomeworkLib. L $python problem.py "this is a string" this is a string <type 'str'> [anonymus@parrot]-[-/Desktop/HomeworkLib]

Rawcode:

import sys
a=sys.argv[1]       #getting first command line as input
try:
    print(eval(a))       #print the result of command line arguement after evaluation
    print(type(eval(a)))   #printing type of result
except (NameError, SyntaxError):   #execption handling for strings as commandline
    print(a)
    print(type(a))

--------------------------------------------------------------------------

b)

Before modification:

1 g=9.81 2 Vo=3 3 t=0.6 4 y=vo*t-0.5*g*t**2 5 print(y2

output:

File Edit View Search Terminal Help lanonymus@parrot]-1-/Desktop/HomeworkLib. $python3 formula.py 0.034199999999999786 anonymus@parrot)-(-/Desktop/HomeworkLib Solutions $python formula.py 0.0342 Canonymus@parrot 1-[-/Desktop/HomeworkLib mit the

RawCode:

g=9.81
vo=3
t=0.6
y=vo*t-0.5*g*t**2
print(y)

--------------------------------

After modification:

i | 2 3 4 5 g=9.81 vo=float(input("Vo= "), t=float(input("t= ")), y=vo*t-0.5*g*t**2 print(y)

sample output:

PYTICE vo= 4 t= 1 [anonymus@parrot]-[-/Desktop/cheg

Rawcode:

g=9.81
vo=float(input("vo= "))
t=float(input("t= "))
y=vo*t-0.5*g*t**2
print(y)

---------------------------------------

c)

1 2 3 4 5 6 import sys g=9.81 vo=eval(sys.argv[i]) treval(sys.argv[2]). y=vo t-0.5*g*t**2 print(y) #eval for converting string to float or integer

sample Output:

[anonymus@parrot]-[-/Desktop/HomeworkLib] $python formula.py 5 3 -29.145 Canonymus@parrot-(-/Desktop/HomeworkLib] Solutions

Rawcode:

import sys
g=9.81
vo=eval(sys.argv[1])   #eval for converting string to float or integer
t=eval(sys.argv[2])
y=vo*t-0.5*g*t**2
print(y)

---------------------------------------------

d)

1 import sys GAWN try: vo=eval (sys.argv[1]) 5 t=eval(sys.argv[2]). 6 except IndexError: t=eval (raw_input("t=")) 8 g=9.81 9 y=vo*t-0.5*g*t**2 10 print(y)

Sample output:

LUNUITYu JUULIUL LIDLJICOP CUCYy - $python formula.py 3 argi t=0.6 0.0342 IndexError: [anonymus@parrot]-[-/Desktop/HomeworkLib]) $ 3D

Rawcode:

import sys

try:
   vo=eval(sys.argv[1])
   t=eval(sys.argv[2])
except IndexError:
    t=eval(raw_input("t="))
g=9.81
y=vo*t-0.5*g*t**2
print(y)

-------------------------------------------------------------

e)

import sys try: Vo=eval(sys.argv[1]) t=eval(sys.argv[2]) except IndexError: t=eval (raw input("t=")), g=9.81 if(0<=t<=2*vo*g): print("ok") else: print("not valid") exit(0) y=vo*t-0.5*g*t**2 print(y)

output:

L $python formula.py 3 t=6 ok y VotSgt 2 - 158.58int(y) (anonymus@parrot -[-/Desktop/HomeworkLib. -- $python formula.py 3 t=88 not valid Canonymus@parrot]-[-/Desktop/HomeworkLib]

Rawcode:

import sys

try:
   vo=eval(sys.argv[1])
   t=eval(sys.argv[2])
except IndexError:
   t=eval(raw_input("t="))
g=9.81
if(0<=t<=2*vo*g):
   print("ok")
else:
   print("not valid")
   exit(0)
y=vo*t-0.5*g*t**2
print(y)

------------------------------------------------------------

f)

1 Imp import sys 2 vo=eval (sys.argv[1]) 3 u=eval (sys.argv[2]) 4 g=9.81 5 Vo=v0*18/5 #convertion from kmph to mps 6 d=(1/2) *v0*2/(u*g) 7 print(d)

output:

lanonymus@parrot-r-/Desktop/HomeworkLib. $python3 formula.py 120 0.3 146.78899082568807 [anonymus@parrot -[-/Desktop/HomeworkLib) $python3 formula.py 500.3 61.162079510703364 [anonymus@parrot]-[-/Desktop/HomeworkLib] - $ de CD Vo (ug) (anonymus@parrot]--/Desktop/HomeworkLib.

Rawcode:

import sys
vo=eval(sys.argv[1])
u=eval(sys.argv[2])
g=9.81
vo=vo*18/5   #convertion from kmph to mps
d=(1/2)*vo*2/(u*g)
print(d)

----------------------------------------------

Hope you understand.If you any doubts comment me.Upvote me.

i 2 3 import sys a=sys.argv[1] #getting first command line as input try: print(eval(a)) #print the result of command line arguement after evaluation print(type (eval(a))) #printing type of result except (NameError, SyntaxError): #execption handling for strings as commandline, print(a) print(type(a)) 6

$python problem.py 6 6 <type 'int'> rint (type (eval(a))) [anonymus@parrot]-[-/Desktop/HomeworkLib Error $python problem.py -45 -45 mint type a.) <type 'int'> (anonymus@parrot]-[-/Desktop/HomeworkLib) $python problem.py -45.4 -45.4 <type 'float'> (anonymus@parrot -[-/Desktop/HomeworkLib. - $python problem.py "[1,2,3,4]" [1, 2, 3, 4] <type 'list'> (anonymus@parrot]-[-/Desktop/HomeworkLib) $python problem.py "(3,4,3)" (3, 4, 3) <type 'tuple'> (anonymus@parrot]-[-/Desktop/HomeworkLib. L $python problem.py "this is a string" this is a string <type 'str'> [anonymus@parrot]-[-/Desktop/HomeworkLib]

1 g=9.81 2 Vo=3 3 t=0.6 4 y=vo*t-0.5*g*t**2 5 print(y2

File Edit View Search Terminal Help lanonymus@parrot]-1-/Desktop/HomeworkLib. $python3 formula.py 0.034199999999999786 anonymus@parrot)-(-/Desktop/HomeworkLib Solutions $python formula.py 0.0342 Canonymus@parrot 1-[-/Desktop/HomeworkLib mit the

i | 2 3 4 5 g=9.81 vo=float(input("Vo= "), t=float(input("t= ")), y=vo*t-0.5*g*t**2 print(y)

PYTICE vo= 4 t= 1 -0.905 [anonymus@parrot]-[-/Desktop/cheg

1 2 3 4 5 6 import sys g=9.81 vo=eval(sys.argv[i]) treval(sys.argv[2]). y=vo t-0.5*g*t**2 print(y) #eval for converting string to float or integer

[anonymus@parrot]-[-/Desktop/HomeworkLib] $python formula.py 5 3 -29.145 Canonymus@parrot-(-/Desktop/HomeworkLib] Solutions

1 import sys GAWN try: vo=eval (sys.argv[1]) 5 t=eval(sys.argv[2]). 6 except IndexError: t=eval (raw_input("t=")) 8 g=9.81 9 y=vo*t-0.5*g*t**2 10 print(y)

LUNUITYu JUULIUL LIDLJICOP CUCYy - $python formula.py 3 argi t=0.6 0.0342 IndexError: [anonymus@parrot]-[-/Desktop/HomeworkLib]) $ 3D

import sys try: Vo=eval(sys.argv[1]) t=eval(sys.argv[2]) except IndexError: t=eval (raw input("t=")), g=9.81 if(0<=t<=2*vo*g): print("ok") else: print("not valid") exit(0) y=vo*t-0.5*g*t**2 print(y)

L $python formula.py 3 t=6 ok y VotSgt 2 - 158.58int(y) (anonymus@parrot -[-/Desktop/HomeworkLib. -- $python formula.py 3 t=88 not valid Canonymus@parrot]-[-/Desktop/HomeworkLib]

1 Imp import sys 2 vo=eval (sys.argv[1]) 3 u=eval (sys.argv[2]) 4 g=9.81 5 Vo=v0*18/5 #convertion from kmph to mps 6 d=(1/2) *v0*2/(u*g) 7 print(d)

lanonymus@parrot-r-/Desktop/HomeworkLib. $python3 formula.py 120 0.3 146.78899082568807 [anonymus@parrot -[-/Desktop/HomeworkLib) $python3 formula.py 500.3 61.162079510703364 [anonymus@parrot]-[-/Desktop/HomeworkLib] - $ de CD Vo (ug) (anonymus@parrot]--/Desktop/HomeworkLib.