I am learning python and I meet some troubles.
I want to write the script to reverse a negative integer " -1234 to 4321- " and non-integer " 1.234 to 432.1". please help me. P.S. cannot use "str()" function
I just only can write the script to reverse positive integer 1234 to 4321
def reverse_int(n):
x = 0
while n > 0:
x *= 10
x += n % 10
n /= 10
return x
print reverse_int(1234)
def reve(x):
x=str(x)
if x[0]=='-':
a=x[::-1]
return f"{x[0]}{a[:-1]}"
else:
return x[::-1]
print(reve("abc"))
print(reve(123))
print(reve(-123))
#output cba 321 -321
how about using your code, but just concatenate a - when n is negative?
rev_int.py:
def reverse_int(m):
x = 0
n = m
if m < 0 :
n *= -1
while n > 0 :
x *= 10
x += n % 10
n /= 10
if m < 0:
#concatenate a - sign at the end
return `x` + "-"
return x
print reverse_int(1234)
print reverse_int(-1234)
This produces:
$ python rev_int.py
4321
4321-
return `x` + "-"?print to a function and /= to //=).str()? You might as well just do return `m`[::-1].repr() matches the spirit of the question any better than using str(), 2. the question clearly mentions non-integers in both the title and the body, giving an example of 1.234, and 3. if you're going to use repr()/``, you might as well replace the whole body of the function with return repr(m)[::-1], and then it'll work on Python 2 and 3, for both ints and floats.Using SLICING EASILY DONE IT
def uuu(num):
if num >= 0:
return int(str(num)[::-1])
else:
return int('-{val}'.format(val = str(num)[1:][::-1]))
Below code runs fine on Python-3 and handles positive and negative integer case. Below code takes STDIN and prints the output on STDOUT.
Note: below code handles only the integer case and doesn't handles the non-integer case.
def reverseNumber(number):
x = 0
#Taking absolute of number for reversion logic
n = abs(number)
rev = 0
#Below logic is to reverse the integer
while(n > 0):
a = n % 10
rev = rev * 10 + a
n = n // 10
#Below case handles negative integer case
if(number < 0):
return (str(rev) + "-")
return (rev)
#Takes STDIN input from the user
number=int(input())
#Calls the reverseNumber function and prints the output to STDOUT
print(reverseNumber(number))
Using str convert method.
num = 123
print(str(num)[::-1])
Use this as a guide and make it work for floating point values as well:
import math
def reverse_int(n):
if abs(n) < 10:
v = chr(abs(n) + ord('0'))
if n < 0: v += '-'
return v
else:
x = abs(n) % 10
if n < 0: return chr(x + ord('0')) + reverse_int(math.ceil(n / 10))
else: return chr(x + ord('0')) + reverse_int(math.floor(n / 10))
print reverse_int(1234)
Why not just do the following?:
def reverse(num):
revNum = ''
for i in `num`:
revNum = i + revNum
return revNum
print reverse(1.12345)
print reverse(-12345)
These would print 54321.1 and 54321-.
return `m`[::-1] comment exactly instead of adding a loop. And, of course, I don't think repr() (what `` does in Python 2 - repr() would be better anyway because it works in 2 and 3) is any better than str().
4321-in not a valid number! do you want to convert it to string?str(), not that he cannot use strings. Hence,def reverse_int(n): return '{}'.format(n)[::-1]should work.strfunction