I’m just starting to learn functions and I am practicing on implementing some into my code. Just a simple example... how can I code this to loop properly and break out when the user wants?
def profit(i,c):
gain = c - i
print('Your profit is:' + '' + str(gain))
def beginning():
x = float(input("What was your initial investment?"))
y = float(input("What is your investment worth now?"))
profit(x,y)
beginning()
ans = 'y'
while ans == 'y' or ans == 'Y':
ans = str(input('Would you like to calculate another investment? (Y/N)'))
beginning()
if ans != 'y' or ans != 'Y':
break
There are two ways to break out of a while loop. The first way is obviously the break statement, kind of like you have done. For it to work correctly, you need to change the condition:
if ans != 'y' or ans != 'Y':
break
This will always be true, since ans cannot be "y" and "Y" at the same time. You should change it into:
if ans not in ["y", "Y"]:
Or
if ans.upper() != "Y":
In your case however, you don't need it at all. Since in both the if statement and the while condition you are checking ans, you can get rid of the if and just rely on this.
while ans.upper() == "Y":
This will end the loop automatically when ans becomes anything other than "Y" or "y".
The only reason you would use a break here is if you wanted to exit the loop immediately, and not complete the current iteration. For example:
while ans.upper() == "Y":
ans = input("Enter selection: ")
if ans == "I want to stop right now!":
break
print("Do other things, even if ans is not Y")
In this example, "Do other things" will always be printed regardless of ans, unless ans is "I want to stop", in which case it won't get printed.
One thing you can do is ans = ans.capitalize() after you get the user input. Then remove the ans != 'y' since that's causing your loop to break.
Related
I've been trying to solve the issue with guessing the number program,
The first number the program has to print Ans which is (Startlow + Starthigh)/2 and then Ans gets updated depends on the input
I can't figure out why my while loop keeps waiting for the input for at least 2 times until it prints the results even if I press l or h (unless I press c) which breaks the loop
Startlow = 0
Starthigh = 100
Ans = (Startlow + Starthigh)/2
print("Please think of a number between 0 and 100!")
while True:
print("Is your secret number " + str(int(Ans)))
if input() == "c":
print("Game over,Your secret number was: "+str(int(Ans)))
break
elif input() == "l":
Startlow = Ans
Ans = (Startlow + Starthigh)/2
elif input() == "h":
Starthigh = Ans
Ans = (Startlow + Starthigh)/2
else:
print("Sorry, I did not understand your input.")
any help appreciated :)
You should be asking for input once in the loop, and then comparing that answer to the items you want.
You are instead requesting a (potentially different) answer at each of your conditionals.
The number of questions asked depends on how many conditionals you fall through.
Just do:
x = input()
if x == "c":
#And so on...
I'm new to python and I'm trying to write a program that will guess the users number.
I'm trying to change the range that's in a while loop, depending on the users answer, but i'm not sure how can I do that.
list = range(100)
half = len(list)//2
def the_guess():
guess = "n"
while guess != "y":
guess = input('is it ' + str(len(list)//2) + '? up(+) or down(-) ?\n')
if guess == 'y':
print('I knew it!!')
break #stops loop?
else:
if guess == '+':
print(list[half:])
# use second part of the range
if guess == '-':
print(list[:half])
# use first part of the range
else:
print("ok, let's try again\n")
the_guess()
The loop works, i'm just not sure how to go about changing the value of the range to something other than 100.
for example:
if the user inputs a "+" I want the range to change to 50 - 100, and will continue to dividing it depending on the users input.
I am a beginner student in a python coding class. I have the majority of the done and the program itself works, however I need to figure out a way to make the program ask if wants a subtraction or an adding problem, and if the user would like another question. I asked my teacher for assistance and he hasn't gotten back to me, so I'm simply trying to figure out and understand what exactly I need to do.
import random
x = int(input("Please enter an integer: "))
if x < 0:
x = 0
print('Negative changed to zero')
elif x == 0:
print('Zero')
elif x == 1:
print('Single')
else:
print('More')
maximum = 10 ** x;
maximum += 1
firstnum = random.randrange(1,maximum) # return an int from 1 to 100
secondnum = random.randrange(1, maximum)
compsum = firstnum + secondnum # adds the 2 random numbers together
# print (compsum) # print for troubleshooting
print("What is the sum of", firstnum, " +", secondnum, "?") # presents problem to user
added = int(input("Your answer is: ")) # gets user input
if added == compsum: # compares user input to real answer
print("You are correct!!!")
else:
print ("Sorry, you are incorrect")
You'll want to do something like this:
def foo():
print("Doing good work...")
while True:
foo()
if input("Want to do more good work? [y/n] ").strip().lower() == 'n':
break
I've seen this construct (i.e., using a break) used more often than using a sentinel in Python, but either will work. The sentinel version looks like this:
do_good_work = True
while do_good_work:
foo()
do_good_work = input("Want to do more good work? [y/n] ").strip().lower() != 'n'
You'll want to do more error checking than me in your code, too.
Asking users for input is straightforward, you just need to use the python built-in input() function. You then compare the stored answer to some possible outcomes. In your case this would work fine:
print('Would you like to test your adding or subtracting skills?')
user_choice = input('Answer A for adding or S for subtracting: ')
if user_choice.upper() == 'A':
# ask adding question
elif user_choice.upper() == 'S':
# ask substracting question
else:
print('Sorry I did not understand your choice')
For repeating the code While loops are your choice, they will repeatedly execute a statement in them while the starting condition is true.
while True: # Condition is always satisfied code will run forever
# put your program logic here
if input('Would you like another test? [Y/N]').upper() == 'N':
break # Break statement exits the loop
The result of using input() function is always a string. We use a .upper() method on it which converts it to UPPERCASE. If you write it like this, it doesn't matter whether someone will answer N or n the loop will still terminate.
If you want the possibility to have another question asked use a while loop and ask the user for an input. If you want the user to input whether (s)he want an addition or substraction you already used the tools to ask for such an input. Just ask the user for a string.
it shows error ---> add_charge referenced before assign
when initial value of ans is not "y" or "n"
function choice(ans) ----> assign add_charge(additional charge) according to input user
gave
def choice(ans):
if ans == "Y" or ans =="y" or ans == "Yes" or ans == "yes":
add_charge = 100
elif ans == "N" or ans =="n"or ans =="No"or ans =="no":
add_charge = 0
else:
ans = f_ans() # if ans is other then y or n, ask user again and assign value
choice(ans)
return add_charge
You are using recursion where you should use a while loop.
When a user picks something other than yes or no (or variants thereof), you end up in the else branch and call choice(). That function call eventually returns, and at that moment add_charge is not set.
You can 'fix' that issue by assigning the return value:
else:
ans = f_ans() # if ans is other then y or n, ask user again and assign value
add_charge = choice(ans)
but you should really use a loop here; that way you don't run into namespace issues and won't ever run out of stack either. All it takes is someone holding the ENTER key for you to run into the maximum recursion limit.
You can use str.lower() and a set membership test to simplify your tests as well:
def choice():
while True:
ans = f_ans()
if ans.lower() in {'y', 'yes'}:
return 100
elif ans.lower() in {'n', 'no'}:
return 0
The return statements will exit the function, but if neither branch is met (the user gave something other than a valid answer), the while loop goes back to the top and f_ans() is called again to ask for a valid answer.
Hello fellow programmers,
I'm quite a Python and overall programming newbie and I don't know how to process user input the bestimmt. A friend of mine suggested while loops and they worked quite well but now I have a serious problem.
The program is about asking the user which one of 3 ways to calculate Pi he wants. After his/her selection, e.g. the way to calculate Pi using a polygon which doubles the number of corners after each iteration, it asks how many digit the user wants to see or how many loops should be calculated etc. I also have added some code that checks what the user has written, e.g. if the user is asked to either type y or n but types b the program reminds him of that and asks again.
This style has led to whiles, inside whiles, inside whiles and now looks more like HTML code than Python and is a little complicated to understand...
Take a look:
#!/usr/bin/python
# -*- coding: iso-8859-15 -*-
prgrm_ctrl_main_while_start = 0
while prgrm_ctrl_main_while_start == 0:
print "Please select the type of algorithm you want to calculate Pi."
usr_ctrl_slct_algrthm = raw_input("'p' to use polygons, 'm' to use the Monte-Carlo algorithm or 'c' for the Chudnovsky algorithm: ")
print " "
if usr_ctrl_slct_algrthm == 'p':
#import libraries
import time
from mpmath import *
#starting values
n_corners = mpf(8)
counter = 0
while_loop_check_itertions = 0
while while_loop_check_itertions == 0:
print "Pi will be calculated more precisely the more iterations you select but it'll also take longer!"
loops = int(input("Please select number of iterations (1 - 10.000.000): "))
print " "
if 1 <= loops <= 10000000:
loops = loops - 1
decimals = int(input("Please select the amount of decimals you want to see: "))
print " "
decimals = decimals + 1
starttime = time.clock()
mp.dps = decimals
while counter <= loops:
counter = counter + 1
n_corners = mpf(n_corners) * mpf(2)
circle = mpf(360)
alpha = mpf(circle) / mpf(n_corners)
beta = mpf(alpha) / mpf(2)
radiansBeta = mpf(mp.radians(beta))
opp_leg = mpf(mp.sin(radiansBeta))
edge_lngth = mpf(opp_leg) * mpf(2)
circmfrnce = mpf(n_corners) * mpf(edge_lngth)
pi = mpf(circmfrnce) / mpf(2)
print "Pi: ", mpf(pi)
print "Time to calculate: ", time.clock() - starttime, "seconds"
print " "
prgrm_ctrl_p_algrthm_while_start = 0
while prgrm_ctrl_p_algrthm_while_start == 0:
usr_ctrl_slct_p_algrthm = raw_input("Would you like to try this algorithm again? (y/n): ")
print " "
if usr_ctrl_slct_p_algrthm == 'y':
usr_ctrl_slct_p_algrthm_slction = 0
break
elif usr_ctrl_slct_p_algrthm == 'n':
usr_ctrl_slct_p_algrthm_slction = 1
break
else:
print "You must either type 'y' or 'n'!"
continue
if usr_ctrl_slct_p_algrthm_slction == 0:
continue
else:
usr_ctrl_slct_diffrt_algrthm_while_start = 0
while usr_ctrl_slct_diffrt_algrthm_while_start == 0:
usr_ctrl_slct_diffrt_algrthm = raw_input("Do you want to use another algorithm? (y/n): ")
print " "
if usr_ctrl_slct_diffrt_algrthm == 'y':
usr_ctrl_slct_diffrt_algrthm_slction = 0
break
elif usr_ctrl_slct_diffrt_algrthm == 'n':
print "See you next time!"
print " "
usr_ctrl_slct_diffrt_algrthm_slction = 1
break
else:
print "You must either type 'y' or 'n'!"
continue
if usr_ctrl_slct_diffrt_algrthm_slction == 0: #The program gets to this line and in case of the user selecting 'y' should continue in the first while-loop
continue
else: #if the user says 'n' the program should interrupt and stop, in the best case it should close the command line (in my case IDLE)
break #instead of doing all this the code gets executed again in the 2nd while loop not the 1st
"""NOTE: I also know the lines above continue or quit the 2nd while-loop"""
elif loops < 1:
print "Please select at least one iteration!"
while_loop_check_algrthm_slct = 0
while while_loop_check_algrthm_slct == 0:
usr_ctrl_slct_algrthm_p_try_agn = raw_input("Do you want to try it again? (y/n): ")
print " "
if usr_ctrl_slct_algrthm_p_try_agn == 'y':
usr_ctrl_slct_algrthm_p_try_agn_slction = 0
break
elif usr_ctrl_slct_algrthm_p_try_agn == 'n':
usr_ctrl_slct_algrthm_p_try_agn_slction = 1
break
else:
print "You must either type 'y' or 'n'!"
continue
if usr_ctrl_slct_algrthm_p_try_agn_slction == 1:
break
else:
continue
else:
print "The maximum amount of iterations is 10 million!"
while_loop_check_algrthm_slct = 0
while while_loop_check_algrthm_slct == 0:
usr_ctrl_slct_algrthm_p_try_agn = raw_input("Do you want to try it again? (y/n): ")
print " "
if usr_ctrl_slct_algrthm_p_try_agn == 'y':
usr_ctrl_slct_algrthm_p_try_agn_slction = 0
break
elif usr_ctrl_slct_algrthm_p_try_agn == 'n':
usr_ctrl_slct_algrthm_p_try_agn_slction = 1
break
else:
print "You must either type 'y' or 'n'!"
continue
if usr_ctrl_slct_algrthm_p_try_agn_slction == 1:
break
else:
continue
I have commented the lines that are effected...
I can't solve the problem with the main-while-loop therefore I'm asking you how I can solve this. Is there a better way of handling user input and checking if it's correct? I'm stuck at a point where I wish I had goto because I can't imagine any other solution.
Hopefully you can help me and thank you for reading this long code! I appreciate that! :)
holofox
My first thought is simplify things, please see this "pseudo-code":
while True: #select algorithm type
#code: ask for algorithm
if answer not in "pmc":
#some message
continue #non-valid algorithm selected, ask again
#...
if answer == 'p':
while True: #select iteration range
#code: ask for iteration
if answer_not_in_range:
#some message
continue #non-valid iteration value, ask again
#...
#perform calculation upon valid selections
#...
#calculation ends
#code: ask for try again with other iteration (algorithm stays same)
if answer != "yes":
break #break out of "iteration" loop
#else loop continues asking for new iteration
#code: ask for try again with other algorithm
if answer != "yes":
break #"algorithm" loop ends, program ends
As Robert Rossney says in an answer to another question:
My first instinct would be to refactor the nested loop into a function and use return to break out.