Hướng dẫn check positive integer python

Asked 7 years, 11 months ago

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I need to check whether what the user entered is positive. If it is not I need to print an error in the form of a msgbox.

number = input("Enter a number: ")
   ###################################

   try:
      val = int(number)
   except ValueError:
      print("That's not an int!")

The above code doesn't seem to be working.

Any ideas?

jww

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asked Oct 4, 2014 at 23:22

5

while True:
    number = input("Enter a number: ")
    try:
        val = int(number)
        if val < 0:  # if not a positive int print message and ask for input again
            print("Sorry, input must be a positive integer, try again")
            continue
        break
    except ValueError:
        print("That's not an int!")     
# else all is good, val is >=  0 and an integer
print(val)

answered Oct 4, 2014 at 23:32

7

what you need is something like this:

goodinput = False
while not goodinput:
    try:
        number = int(input('Enter a number: '))
        if number > 0:
            goodinput = True
            print("that's a good number. Well done!")
        else:
            print("that's not a positive number. Try again: ")
    except ValueError:
        print("that's not an integer. Try again: ")

a while loop so code continues repeating until valid answer is given, and tests for the right input inside it.

answered Oct 4, 2014 at 23:37

W1ll1amvlW1ll1amvl

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0

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Trong ví dụ Python Tuple này, chúng tôi đã tạo một hàm trả về số lượng số Dương và Số âm.

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