Solve Python Woes: How to Get a Five Digit Number Input in One Try

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SUMMARY

The forum discussion addresses a common issue in Python programming regarding input validation for a five-digit number. The original code incorrectly checks the input range, leading to an infinite loop when invalid input is provided. The correct approach involves using the condition `while not (10000 <= x <= 99999)`, which effectively validates the input. Additionally, the discussion highlights the difference between Python's input handling and Java's, emphasizing the need for type conversion in Python.

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OrbitalPower
python woes:

Code:
~/code/python$ cat five.py
#!/usr/bin/env python

x = input('Enter a five digit number: ')
while (not(x < 10000 and x > 99999)):
        x = input('Five digits please: ')

firstDigit  =  x / 10000
secondDigit = (x / 1000) % 10
thirdDigit  = (x / 100)  % 10
fourthDigit = (x / 10)   % 10
fifthDigit  =  x         % 10

print "The digit a is", firstDigit, secondDigit, thirdDigit, fourthDigit, fifthDigit
(1)~/code/python$ ./five.py
Enter a five digit number: 54
Five digits please: 54321
Five digits please: dang
Traceback (most recent call last):
  File "./five.py", line 5, in ?
    x = input('Five digits please: ')
  File "<string>", line 0, in ?


I don't understand why it asks for five digits again.

My original code was this:

Code:
x = input('Enter a five digit number: ')
while (x <= 9999 or x >= 99999):
        x = input('Five digits please: ')

The statements should have been equivalent but it causes problems when I do it the first way.

In java:

x = input.nextInt();
while (!(x > 10000 && x < 99999))
{
System.out.println("Five digits retard: ");
x = input.nextInt();
}

It works like it's supposed to i believe.
 
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The python code throws an exception when you try and divide the work 'dang' by 10000

The java code "input.nextInt()" makes the input an int (I don't know java, presumably it returns 0 for 'dang'?)
 
"The statements should have been equivalent but it causes problems when I do it the first way."

I don't know python, but have you tried others way like

e.g.
x = 0
while (not(x < 10000 and x > 99999)):
x = input('Five digits please: ')

or put while in different way:
while (not(x < 10000)):
while (not(x > 99999)):

Usually when the code doesn't work I try to use different ways..
 
mgb_phys said:
The python code throws an exception when you try and divide the work 'dang' by 10000

The java code "input.nextInt()" makes the input an int (I don't know java, presumably it returns 0 for 'dang'?)

I typed "dang" because i believe it should have exited the while loop at that point.

rootX said:
I don't know python, but have you tried others way like

e.g.
x = 0
while (not(x < 10000 and x > 99999)):
x = input('Five digits please: ')

or put while in different way:
while (not(x < 10000)):
while (not(x > 99999)):

Usually when the code doesn't work I try to use different ways..

rootX said:
I don't know python, but have you tried others way like

e.g.
x = 0
while (not(x < 10000 and x > 99999)):
x = input('Five digits please: ')

or put while in different way:
while (not(x < 10000)):
while (not(x > 99999)):

Usually when the code doesn't work I try to use different ways..


Another equivalent statement would be not(x>10000) or not(x < 99999).

I will try them, but really I can already can get it to work fine, I just wondered why it'd stay in the loop on seemingly equivalent statements.
 
OrbitalPower said:
I will try them, but really I can already can get it to work fine, I just wondered why it'd stay in the loop on seemingly equivalent statements.

one way is to debug..
Code:
x = 50000; // try 10000, 99999, 9999, upperlimit+1 .. 
//Print x, boolean, ... 
while (not(x < 10000 and x > 99999)):
        PRINT "I am in loop"

PRINT "I am out"
 
"not(x < 10000 and x > 99999)"

Think about this for a moment. When will a number ever be both less than 10000 and greater than 99999? Never! So this statement is always true.
 
Yes, I wrote the signs the wrong way in the python version for some reason and wasn't paying attention. I'm sure it'll work when I reverse them.
 
Incidentally, python has some syntactic sugar for intervals: your test could be

while not (10000 <= x <= 99999):
 

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