I'm new to programming and I'm stuck with an exercise, I hope someone can help.
The problem is the following:
1)Write a function that repeatedly asks the user to insert a number and computes the sum of those numbers
2)When the user inserts 0, exit and print the value of the sum.
Now this is the code i managed to write, but if my variable keeps increasing the input will never b 0 and the program will run forever...
def mysum():
n=1
while n>0:
n=n+int(input('Insert a value: '))
print(n)
Now when I call the function it keeps addings the sum of the numbers the users wrote, but how can I going on with the 2nd point of the exercise?
thank you
You're close! Loop forever (while True) and break when the user gives a 0
def mysum():
n = 0
while True:
new = input('Insert a value: ')
# validate the new input can be made a number
try:
new = float(new)
except ValueError:
print('invalid input, try again')
continue
if not new: # or new == 0
break
n += new
print(n)
Instructions: Create a program that asks a user to enter a series of numbers. The user should enter a negative number to signal the end of the series. After all the positive numbers have been entered, the program should display their sum.
I am using Python 2, Python IDLE
I'm using a while loop for this assignment. So far, I made a program that is saying, while the user enters a positive number under the while loop, collect that number and keep adding it until the user enters a negative number. I am trying to find a way to include the first user input into the program.
print('This program calculates the sum of the numbers entered and ends
after inputting a negative number')
total = 0.00
number = float(input('Enter a number: '))
while number >= 0:
print('Enter another positive value if you wish to continue. Enter a
negative number to calculate the sum.')
number = float(input('Enter a number: '))
total = total + number
print('The sum is', total)
Have reduced your code to the below.
Performs checking of input in while loop and exits upon negative value.
total = 0.00
while True:
print('Enter another positive value if you wish to continue. Enter a negative number to calculate the sum.')
number = float(input('Enter a number: '))
if number >= 0: # Check for positive numbers in loop
total += number
else:
break
print('The sum is', total)
I assume you're a beginner, so firstly welcome to Python! I hope you're having fun. Now, as far as your code goes, there are two things I noticed off the bat:
You can simply put this 'Enter another positive value if you wish to continue.
Enter a negative number to calculate the sum.' inside your input, why bother
with an extra print statement?
You don't have to call the input() function twice.
Here's how I'd do it:
print('This program calculates the sum of the numbers entered and ends
after inputting a negative number')
total = 0.00
while True:
number = float(input("Enter a positive number(Negative number if you wish to terminate program"))
if number >=0:
total += number #equivalent to total=total + sum
else:
break # break out of while loop
print('The sum is', total)
P.S - Why are you using Python 2 btw ?
I have an assignment as follows
Write a program that repeatedly asks the user to enter a number, either float or integer until a value -88 is entered. The program should then output the average of the numbers entered with two decimal places. Please note that -88 should not be counted as it is the value entered to terminate the loop
I have gotten the program to ask a number repeatedly and terminate the loop with -99 but I'm struggling to get it to accept integer numbers (1.1 etc) and calculate the average of the numbers entered.
the question is actually quite straightforward, i'm posting my solution. However, please show us your work as well so that we could help you better. Generally, fro beginners, you could use the Python built-in data types and functions to perform the task. And you should probably google more about list in python.
def ave_all_num():
conti = True
total = []
while conti:
n = input('Input value\n')
try:
n = float(n)
except:
raise ValueError('Enter values {} is not integer or float'.format(n))
if n == -88:
break
total.append(n)
return round(sum(total)/len(total),2)
rslt = ave_all_num()
Try the following python code. =)
flag = True
lst=[]
while(flag):
num = float(raw_input("Enter a number. "))
lst+=[num]
if(num==-88.0): flag = False
print "Average of numbers: ", round( (sum(lst[:-1])/len(lst[:-1])) , 2)
enter code hereThank you for the prompt replies. Apologies. This is the code i was working on:
`#Assignment2, Question 3
numbers=[]
while True:
num=int(input("Enter any number:"))
if num==float:
continue
if num==-88:
break
return print(" the average of the numbers entered are:",sum(numbers)/len(numbers)`
I am a new learner for Python. I have a question about while loop.
I wrote a program below to look for square roots.
When I input anything but integers, the message "is not an integer" shows up and it repeats itself until I input correct data(integers).
My question is, why does it end loop when it return value on line 5, return(int(val))?
Thank you for your attention.
def readInt():
while True:
val = input('Enter an integer: ')
try:
return(int(val))
except ValueError:
print(val, "is not an integer")
g = readInt()
print("The square of the number you entered is", g**2)
To answer your original question, 'return' effectively exits the loop and provide the result that follows the 'return' statement, but you have to explicity print it like so:
def read_int(num1, num2):
while True:
return num1 + num2
print(read_int(12, 15))
If you simply put 'read_int(12, 14)' instead of 'print(read_int(12, 15))' in this scenario, you won't print anything but you will exit the loop.
If you allow me, here are some modifications to your original code:
def read_int(): # functions must be lowercase (Python convention)
while True:
val = input('Enter an integer: ')
try:
val = int(val) # converts the value entered to an integer
minimum_value = 0 # There is no need to evaluate a negative number as it will be positive anyway
maximum_value = 1000000 # Also, a number above 1 million would be pretty big
if minimum_value <= val <= maximum_value:
result = val ** 2
print(f'The square of the number you entered is {result}.')
# This print statement is equivalent to the following:
# print('The square of the number you entered is {}.'.format(result))
break # exits the loop: else you input an integer forever.
else:
print(f'Value must be between {minimum_value} and {maximum_value}.')
except ValueError: # If input is not an integer, print this message and go back to the beginning of the loop.
print(val, 'is not an integer.')
# There must be 2 blank lines before and after a function block
read_int()
With the final 'print' that you actually have at the end of your code, entering a string of text in the program generates an error. Now it doesn't ;). Hope this is useful in some way. Have a great day!
Objective: * Write a python program that repeatedly prompts for input of a positive number until the sum of the numbers is greater than 179. Use at least three modules/functions in your solution.
* The largest number entered cannot exceed 42.
* When the sum of the numbers exceeds 179, print the sum of the numbers, the largest number entered and smallest number entered.
I just need some guidance, specifically for the "input_numbers" module. There must be an easier way to do this than to make a variable for each number. The code is not complete. I haven't even started on the two other modules yet. Thanks in advance.
def input_numbers():
while True:
num1 = raw_input("Enter a positive integer no greater than 42 ")
if num1 <= 0:
print "That is not a positive integer. Try again "
elif num1 > 42:
print "The number cannot exceed 42. Try again "
num2 = raw_input("Enter another positive integer ")
if num2 <= 0:
print "That is not a positive integer. Try again "
elif num2 > 42:
print "The number cannot exceed 42. Try again "
num3 = raw_input("Enter another positive integer ")
if num3 <= 0:
print "That is not a positive integer. Try again "
elif num3 > 42:
print "The number cannot exceed 42. Try again "
num4 = raw_input("Enter another positive integer ")
if num4 <= 0:
print "That is not a positive integer. Try again "
elif num4 > 42:
print "The number cannot exceed 42. Try again "
num5 = raw_input("Enter another positive integer ")
if num5 <= 0:
print "That is not a positive integer. Try again "
elif num5 > 42:
print "The number cannot exceed 42. Try again "
elif sum(num1, num2, num3, num4, num5) > 179:
print_numbers()
add_numbers()
def add_numbers():
print_numbers()
def print_numbers():
input_numbers()
You can knock out all three function requirements by encapsulating each step of your program. Rather than having your loop inside of a function, we'll let main control the loop, and we'll control the flow by passing data into and out of function calls.
Let's rework your input_numbers() function a bit.
def get_input_number():
num = int(raw_input("Enter a positive integer no greater than 42 "))
if num <= 0 or num > 42:
print "Invalid input. Try again "
get_input_number()
else:
return num
So, instead of having input_numbers control the loop as well as the input handling and validation, we have it do just what its name implies: It asks for input, validates it, and then, if it's good, it returns the value to the caller, but if it's bad, it writes a message, and calls itself again to the user can enter good input.
The next function we'll set up is straight from your list of requirements. From all of the numbers that the user enters, we need to find the biggest one. From the language alone, we can determine that we're looking through a set of numbers, and thus, this is a good place to break out a list. Assuming we store all of the users input in a list, we can then pass that list to a function and perform operations on it, like so.
def get_greatest_number(input_list):
highest = input_list[0]
for i in input_list:
if i > highest:
highest = i
return highest
We set the first element of the list to a variable highest and then check all other elements in the list against that initial value. If we find one that's bigger, we then reassign the highest variable to the element that was bigger. Once we do this for each element in the list, the number inside of highest will now be, just that, the highest number, and so, we'll return it to the main program.
Similarly, we can do the same for finding the smallest.
def get_smallest_number(input_list):
smallest = input_list[0]
for i in input_list:
if i < smallest:
smallest = i
return smallest
Finally, we get to our main loop. Here we declare an empty list, number_list to store all the numbers in. And we use the sum of that as our loop condition.
if __name__ == '__main__':
number_list = []
while sum(number_list) < 179:
number_list.append(get_input_number())
In the body of the loop, we call our get_input_number() and append its result to the list we made. Once the sum of the numbers in the list exceed 179, the while loop will exit and we can finally show the user the results.
print
print '-------------------------'
print 'total of numbers entered: %d' % sum(number_list)
print 'greatest number entered: %d' % get_greatest_number(number_list)
print 'smallest number entered: %d' % get_smallest_number(number_list)
Here we can the get_greatest_number and get_smallest_number we made, and we give them the list of numbers as an argument. They'll loop though the lists, and then return the appropriate values to the print statements.
Yes, of course there's a better way than making a variable for each number. Store them in a list. Storing them in a list also makes finding their sum and the highest and lowest value easy (there are built-in functions for this).
As a further hint, you'll want to use two loops, one inside the other. The outer loop keeps the user entering numbers until their sum exceeds 179. The inner loop keeps the user entering a single number until it's between 1 and 42 inclusive.
def get_int(prompt=''):
while True:
try:
return int(raw_input(prompt))
except ValueError:
pass
def get_values():
values = []
total = 0
while total <= 179:
val = get_int('Enter a positive integer <= 42: ')
if 0 <= val <= 42:
values.append(val)
total += val
return values
def print_info(values):
print 'Sum is {}'.format(sum(values))
print 'Largest value is {}'.format(max(values))
print 'Smallest value is {}'.format(min(values))
def main():
values = get_values()
print_info(values)
if __name__=="__main__":
main()
You can repeatedly poll the number in a loop, and add the inputs into a list, e.g.
def input_numbers():
user_inputs = [] # a list of all user's inputs
while True:
num = raw_input("Enter a positive integer no greater than 42 ")
try:
num = int(num) # convert input string to integer
if num <= 0:
print "That is not a positive integer. Try again "
elif num > 42:
print "The number cannot exceed 42. Try again "
user_inputs.append(num)
except ValueError: # conversion to integer may fail (e.g. int('string') ?)
print 'Not a Number:', num
if some_condition_regarding(user_inputs):
break # eventually break out of infinite while loop
here some well-known tricks:
def min_and_max(your_num_list)
min=your_num_list[0]
max=your_num_list[0]
for num in your_num_list:
if num < min:
min=num
if max > num
max=num
return min,max
When you're writing a standalone Python program, it’s a good practice to use a main function. it allows you to easily add some unit tests, use your functions or classes from other modules (if you import them), etc.
And as others already said, it is a good idea to create a list and append a new element to it each time the user enters a valid number (until the sum of the numbers axceeds 179). If user entered an incorrect value, then just don’t append anything to the list and skip to the next iteration (so the user will be asked to enter a number again).
So basically it could look like this:
def validate_entered_number(num):
"""
Checks if the number is positive and is less or equal to 42.
Returns True if the number matches these conditions,
otherwise it returns False.
"""
if num < 0:
print "That is not a positive integer."
return False
if num > 42:
print "The number cannot exceed 42."
return False
return True
def main():
entered_numbers = []
while True:
try:
num = int(raw_input("Enter a positive integer less or equal to 42: "))
except ValueError:
print "You should enter a number"
continue
if validate_entered_number(num):
entered_numbers.append(num)
if sum(entered_numbers) > 179:
print "The sum of the numbers is %s" % sum(entered_numbers)
print "The smallest number entered is %s" % min(entered_numbers)
print "The largest number entered is %s" % max(entered_numbers)
return
if __name__ == "__main__":
main()
In fact, I can imagine a situation where you would want to just store the sum of the numbers, the smallest number and the largest number in three variables and update these variables in each iteration (add current number to the sum and compare it to the currently known smallest and larger numbers and update the corresponding variables when necessary), but in this case the longest list you can possibly have is only 180 elements (if all numbers are 1 and the user doesn’t enter 0 or you have modified the program to deny entering 0), which is very small amount of elements for a list in Python. But if you had to deal with really big amounts of numbers, I’d recommend to switch to a solution like this.
Thanks to everyone who answered. I've written the following code and it works nearly perfectly except the last module. If you exit the program after the first run (by pressing 0) it will exit, but if you run it a second time pressing 0 won't make it exit. It'll just go back to the beginning of the program. I don't know why.
Note: The assignment has various requirements that I had to incorporate in my code. Hence the unnecessary modules, global variables, and comments.
maxNum = 42 # declares global variable maxNum
target = 179 # declares global variable target
def user_input(): # prompts user to input a number 42 or less until all add up to 179
x = 0
nums = []
while sum(nums) <= target:
nums.append(int(raw_input("Enter a number: ")))
if int(nums[x]) > int(maxNum):
print "Number cannot exceed 42."
user_input()
else:
x += 1
print_nums(nums,x)
def print_nums(nums,x): # prints the sum of the numbers, the smallest, and the largest
print "Sum of all numbers is", sum(nums)
nums.sort()
x -= 1
print "Largest number entered is", nums[x]
print "Smallest number entered is", nums[0]
decide()
def decide(): # allows user to continue the program or exit
exit = raw_input("<9 to enter a new set of number. 0 to exit.> ")
while True:
if int(exit) == 0:
return
elif int(exit) == 9:
user_input()
user_input()