Title:
Gets an input positive integer N and inverts the output of that positive integer, disregarding exceptions.
Input format: Enter a positive integer
output format : output a positive integer
Question:
Why did both of my answers fail the Python Level 2 Online Review test?
My answer one:
num_str = input('Please enter a positive integer:')
# Calculate positive integer digits
num_len = len(num_str)#.count() method is not suitable'
# Method 1
for i in range(-1,-1-num_len,-1):
print(num_str[i],end='')
My answer two:
num_str = input('Please enter a positive integer:')
# Calculate positive integer digits
num_len = len(num_str)The #.count() method is not suitable for the
new_str = ''
for i in range(-1,-1-num_len,-1):#range(5) is equivalent to range(0,5,1)
new_str += num_str[i]
print(new_str)
The correct answer is here:
It was me who desecrated the simple and beautiful Python...
#String reversal s_reverse = s[::-1]
Addendum: Beginning python miscellany - number reversal
Input an integer and output the integer as a string in reverse order.
The program does not take into account the case of negative numbers, if the number contains 0, the inverse form also contains 0, such as the input is 100, the output is 001
print(input()[::-1])
Or:
a=input()
s=str(a)
lis=[]
for i in s:
(i)
()
print(''.join(lis))
Function Description:
[x:y:z] takes values every z in the (x, y) interval, z defaults to 1.
[::-1] Indicates reverse value.
The str() function converts an object to a string.
grammatical
The following is the syntax of the str() method.
class str(object=”)
parameters
object - an object.
return value
Returns an object in string format.
an actual example
The following shows an example of using the str() method:
s = ‘RUNOOB'
str(s)
‘RUNOOB'
dict = {‘runoob': ‘', ‘google': ‘'};
str(dict)
“{‘google': ‘', ‘runoob': ‘'}”
The Python join() method is used to concatenate the elements of a sequence with the specified characters to create a new string.
(sequence)
parameters
sequence - The sequence of elements to concatenate.
return value
Returns the new string generated by concatenating the elements of the sequence with the specified characters.
The following example shows how join() is used:
an actual example
str = “-“; seq = (“a”, “b”, “c”); # String sequences print ( seq );
The output of the above example is as follows: a-b-c
The above is a personal experience, I hope it can give you a reference, and I hope you can support me more. If there is any mistake or something that has not been fully considered, please do not hesitate to advise me.