How check if first digit of integer is zero in python - python

** i want to check if first digit of integer is zero.
If it is zero, i want to leave first digit which is zero and take the rest.
For example num = 0618861552
In this case first digit is zero. I want to get 618861552
If the first digit of num is not zero, i want to take the entire string.
For example num = 618861552
In this case first digit of num is not zero, i want to get 618861552
Below is the code i have tried.
Note that my code works if first digit is not zero but doesn't work if the first digit is zero
**
num = int(input("enter number: "))
#changing int to str to index.
position = str(num)
if int(position[0]) == 0:
len = len(position)
position1 = position[1:len]
print(position1)
else:
len = len(position)
position1 = position [0:len]
print(position1)

This should do:
number = input("enter number: ")
print(number.lstrip('0'))

This would work :
def remove_zero (a) :
a = str(a)
if ord(a[0]) == 48 :
a = a[1:]
return (str(a))
p = int(input("Enter a number :"))
q = remove_zero(p)
print(q)

Actually converting to int remove all leading zero.
num = "0020"
num2 = "070"
num3 = "000000070"
print(int(num))
print(int(num2))
print(int(num3))
Output is
20
70
70
And this way works too:
num = int(input())
print(num)
That is why
Note that my code works if first digit is not zero but doesn't work if
the first digit is zero **
It is always without leading zero after convertion to int

Related

How to print sum of digits for a Python integer? [duplicate]

This question already has answers here:
Sum the digits of a number
(11 answers)
Closed last year.
Consider the following input prompt. I want to output the sum of digits that are inputted.
Example:
two_digit_number = input("Type a two digit number: ") 39
# program should print 12 (3 + 9) on the next line
If I input 39, I want to output 12 (3 + 9). How do I do this?
You can use sum(), transforming each digit to an integer:
num = input("Enter a two digit number: ")
print(sum(int(digit) for digit in num))
maybe like this:
numbers = list(input("Enter number: "))
print(sum(list(map(int, numbers))))
Read digits with input as a whole number of string type
split them with list() in characters in a list
use map() to convert type to int in a list
with sum() you're done.. just print()
Beware of invalid entries! "hundred" or "1 234 567"
you can achieve that like this:
a = input("Type a two digit number: ")
b = list(a)
print(int(b[0])+int(b[1]))
n = (int(input("Enter the two digit number\n")))
n = str(n)
p = int(n[0])+int(n[1])
print(p)
This is one of the many ways for it.
value = 39 # it is your input
value_string = str(value)
total = 0
for digit in value_string:
total += int(digit)
print(total)
new version according to need mentioned in comment:
value = 39
value_string = str(value)
total = 0
digit_list = []
for digit in value_string:
total += int(digit)
digit_list.append(digit)
print(" + ".join(digit_list))
print(total)
You can do that as follows:
two_digit_number = input("Type a two digit number: ")
digits = two_digit_number.split("+")
print("sum = ", int(digits[0])+int(digits[1]))
Explanation:
first read the input (ex: 1+1)
then use split() to separate the input statement into the strings of the input digits only
then use int() to cast the digit from string to int

How do I calculate the sum of the individual digits of an integer and also print the original integer at the end?

I wish to create a Function in Python to calculate the sum of the individual digits of a given number
passed to it as a parameter.
My code is as follows:
number = int(input("Enter a number: "))
sum = 0
while(number > 0):
remainder = number % 10
sum = sum + remainder
number = number //10
print("The sum of the digits of the number ",number," is: ", sum)
This code works up until the last print command where I need to print the original number + the statement + the sum. The problem is that the original number changes to 0 every time (the sum is correct).
How do I calculate this but also show the original number in the print command?
Keep another variable to store the original number.
number = int(input("Enter a number: "))
original = number
# rest of the code here
Another approach to solve it:
You don't have to parse the number into int, treat it as a str as returned from input() function. Then iterate each character (digit) and add them.
number = input("Enter a number: ")
total = sum(int(d) for d in number)
print(total)
You can do it completely without a conversion to int:
ORD0 = ord('0')
number = input("Enter a number: ")
nsum = sum(ord(ch) - ORD0 for ch in number)
It will compute garbage, it someone enters not a number
number = input("Enter a number: ")
total = sum((int(x) for x in list(number)))
print("The sum of the digits of the number ", number," is: ", total)
As someone else pointed out, the conversion to int isn't even required since we only operate a character at a time.

Only the last item is being appended to a list in a while loop (Python)

I'm trying to create a program that gets each digit of an inputted number into a list using a while loop. However, it only appends the last digit of the number to the list.
Code -
num = int(input("Enter a number: "))
numstr = str(num)
numlen = len(numstr)
x = 0
while x < numlen:
digits = []
a = numstr[x]
digits.append(a)
x = x + 1
print(digits)
So if I were to put in 372 as the number, the list would just simply be ['2'] with a length of 1.
Try this code:
digits = [i for i in str(num)]
You cannot do better than digits = list(str(num)). In fact, since input returns a string, even the conversion to a number is not necessary:
num = input("Enter a number: ")
digits = list(num)
(You still may want to ensure that what's typed is indeed a number, not a random string.)

How to pick one number of an Integer

How can I pick one of the digits from an Integer like: 97723
and choose (for example) the number 2 from that number and check if its an odd or an even number?
Also, can I print only the odd numbers from an Integer directly? (Is there any default function for that already?)
Thanks in advance
2 is the 4th digit.
You can get the digits of a number using this construct.
digits = [int(_) for _ in str(97723)]
This expression will be true if the 4th digit is even.
digits[3] % 2 == 0
# choose a digit (by index)
integer = 97723
digit_3 = str(integer)[3]
print(digit_3)
# check if even:
if int(digit_3) % 2 == 0:
print(digit_3, "is even")
# get all odd numbers directly
odd_digits = [digit for digit in str(integer) if int(digit) % 2 == 1]
print(odd_digits)
even = lambda integer: int("".join([num for num in str(integer) if int(num) % 2 == 0]))
or
def even(integer):
result = ""
integer = str(integer)
for num in integer:
if int(num) % 2 == 0:
result += num
result = int(result)
return(result)
If you want to "parse" a number the easiest way to do this is to convert it to string. You can convert an int to string like this s = string(500). Then use string index to get character that you want. For example if you want first character (number) then use this string_name[0], for second character (number) use string_name[1] . To get length of your string (number) use len(string). And to check if number is odd or even mod it with 2.
# Converting int to string
int_to_sting = str(97723)
# Getting number of characters in your string (in this case number)
n_of_numbers = len(int_to_sting)
# Example usage of string index
print("First number in your number is: ",int_to_sting[0])
print("Second number in your number is: ",int_to_sting[1])
# We need to check for every number, and since the first number is int_to_sting[0] and len(int_to_sting) returns actual length of string we need to reduce it by 1
for i in range(n_of_numbers-1):
if int_to_sting[i]%2==0:
print(int_to_sting[i]," is even")
else:
print(int_to_sting[i]," is odd")

ISBN final digit finder

I am working in python 3 and I am making a program that will take in a 10 digit ISBN Number and applying a method to it to find the 11th number.
Here is my current code
ISBN=input('Please enter the 10 digit number: ')
while len(ISBN)!= 10:
print('Please make sure you have entered a number which is exactly 10 characters long.')
ISBN=int(input('Please enter the 10 digit number: '))
continue
else:
Digit1=int(ISBN[0])*11
Digit2=int(ISBN[1])*10
Digit3=int(ISBN[2])*9
Digit4=int(ISBN[3])*8
Digit5=int(ISBN[4])*7
Digit6=int(ISBN[5])*6
Digit7=int(ISBN[6])*5
Digit8=int(ISBN[7])*4
Digit9=int(ISBN[8])*3
Digit10=int(ISBN[9])*2
Sum=(Digit1+Digit2+Digit3+Digit4+Digit5+Digit6+Digit7+Digit8+Digit9+Digit10)
Mod=Sum%11
Digit11=11-Mod
if Digit11==10:
Digit11='X'
ISBNNumber=str(ISBN)+str(Digit11)
print('Your 11 digit ISBN Number is ' + ISBNNumber)
I want to create some kind of loop so that the number after "Digit" for the variable name increases starting from 1 (or zero if it makes life easier), the number in the square brackets increases starting from 0 and the multiplication number to decrease from 11 to 2.
Is there any way of doing this code in a more efficient way?
I think this should do what you want.
def get_isbn_number(isbn):
digits = [(11 - i) * num for i, num in enumerate(map(int, list(isbn)))]
digit_11 = 11 - (sum(digits) % 11)
if digit_11 == 10:
digit_11 = 'X'
digits.append(digit_11)
isbn_number = "".join(map(str, digits))
return isbn_number
EXAMPLE
>>> print(get_isbn_number('2345432681'))
22303640281810242428
>>> print(get_isbn_number('2345432680'))
2230364028181024240X
Explanation of second line:
digits = [(11 - i) * num for i, num in enumerate(map(int, list(isbn)))]
Could be written out like:
isbn_letters = list(isbn) # turn a string into a list of characters
isbn_numbers = map(int, isbn_letters) # run the function int() on each of the items in the list
digits = [] # empty list to hold the digits
for i, num in enumerate(isbn_numbers): # loop over the numbers - i is a 0 based counter you get for free when using enumerate
digits.append((11 - i) * num) # If you notice the pattern, if you subtract the counter value (starting at 0) from 11 then you get your desired multiplier
Terms you should look up to understand the one line version of the code:
map,
enumerate,
list conprehension
ISBN=int(input('Please enter the 10 digit number: ')) # Ensuring ISBN is an integer
while len(ISBN)!= 10:
print('Please make sure you have entered a number which is exactly 10 characters long.')
ISBN=int(input('Please enter the 10 digit number: '))
continue
else:
Sum = 0
for i in range(len(ISBN)):
Sum += ISBN[i]
Mod=Sum%11
Digit11=11-Mod
if Digit11==10:
Digit11='X'
ISBNNumber=str(ISBN)+str(Digit11)
print('Your 11 digit ISBN Number is ' + ISBNNumber)

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