How to check every input for isdigit

isdigit python
c check if input is number
isnumeric python
c check if string is number
isdigit java

I am trying to write a game that generates a random integer and the user has to guess it.

The problem is that if the user input is not a digit it crashes. So I tried to use isdigit, and it works at the beginning, but if the user decides to input not a number after the first input was a digit, it still crashes. I don't know how to make it check isdigit for every input.

import random
x =(random.randint(0,100))
print("The program draws a number from 0 to 100. Try to guess it!")

a = input("enter a number:")
while a.isdigit() == False :
    print("It is not a digit")
    a = input("enter a number:")
if a.isdigit() == True :
    a = int(a)
while a != x :
    if a <= x :
        print("too less")
        a = input("enter a number:")
    elif a >= x :
        print("too much")
        a = input("enter a number")
if a == x :

I would suggest doing the following:

completed = False
while not completed:
   a = input("enter a number: ")
   if a.isdigit():
      a = int(a)
      if a < x:
         print("too little")
      elif a > x:
         print("too much")
         completed = True
      print("It is not a digit")

Python String isdigit() and its application, The isdigit() methods returns “True” if all characters in the string are digits, Input : string = '15460' Output : True Input : string = '154ayush60' Output : False Traverse every character using ascii value, check if the character is a digit. 2. Python string method isdigit() checks whether the string consists of digits only. Syntax. Following is the syntax for isdigit() method − str.isdigit() Parameters. NA. Return Value. This method returns true if all characters in the string are digits and there is at least one character, false otherwise. Example

If your code crashed because the user entered not a number, then either make sure the user enters a number, or handle an error while trying to compare it with a number.

You could go over all chars in the input and ensure that they are all digits.

Or you could use a try/except mechanism. That is, try to convert to the numerical type you wish the user to enter and handle any error throwen. Check this post:

How can I check if a string represents an int, without using try/except?

And also:

C isdigit(), Even though, isdigit() takes integer as an argument, character is passed to the function. Internally, the character is converted to its ASCII value for the check. Following is the declaration for isdigit() function. int isdigit(int c); Parameters. c − This is the character to be checked. Return Value. This function returns non-zero value if c is a digit, else it returns 0. Example. The following example shows the usage of isdigit() function.

The typical pythonic way to tackle that would be to "ask for forgiveness instead of looking before you leap". In concrete terms, try to parse the input as int, and catch any errors:

    a = int(input('Enter a number: '))
except ValueError:
    print('Not a number')

Beyond that, the problem is obviously that you're doing the careful checking once at the start of the program, but not later on when asking for input again. Try to reduce the places where you ask for input and check it to one place, and write a loop to repeat it as often as necessary:

while True:
        a = int(input('Enter a number: '))
    except ValueError:  # goes here if int() raises an error
        print('Not a number')
        continue  # try again by restarting the loop

    if a == x:
        break  # end the loop
    elif a < x:
        print('Too low')
        print('Too high')


isdigit - C++ Reference, int isdigit ( int c );. Check if character is decimal digit. Checks whether c is a decimal digit character. Decimal digits are any of: 0 1 2 3 4 5 6 7 8 9. For a detailed  isdigit() Prototype int isdigit(int ch); The isdigit() function checks if ch is a digit or not i.e one of 0,1,2,3,4,5,6,7,8 and 9. The behaviour of isdigit() is undefined if the value of ch is not representable as unsigned char or is not equal to EOF. It is defined in <cctype> header file. isdigit() Parameters

# user vs randint

import random
computer = random.randint(0,100)
while True:
        user = int(input(" Enter a number : "))
    except (ValueError,NameError):
        print(" Please enter a valid number ")
        if user == computer:
            print(" Wow .. You win the game ")
        elif user > computer:
            print(" Too High ")
            print(" Too low ")

I think this can solve the issues.

isdigit() to validate if input is number.., My task is to check the input given by user..whether it is an INTEGER or for help with some sort of programming or design problem every day. Python Program to find character is Alphabet or Digit using isalpha, isdigit functions. In this example python code, we use string functions called isdigit and isalpha to check whether a given character is an alphabet or digit.

In your code you want to check whether the user has input no or string since your not using int() in your input it will take input as string and furthur in your code it wont be able to check for <= condition

for checking input no is string or no


a = input ("Enter no")
   val = int(a)
   print("Yes input string is an Integer.")
   print("Input number value is: ", a)
except ValueError:
   print("It is not integer!")
   print(" It's a string")

Python String isdigit() Method, No parameters. More Examples. Example. Check if all the characters in the text is alphabetic: a = "\  Python input() function always convert the user input into a string. but how to check user input is a number. We can Convert string input to int or float type to check string input is an integer type. also using isdigit() method of string class we can check input string is number or string.

How You Make Sure input() Is the Type You Want It to Be in Python, The function to check for int can be: def is_digit(check_input): if check_input. isdigit(): return True return False. This checks if all the characters in  Similarly, isdigit(c) is a function in C which can be used to check if the passed character is a digit or not. It returns a non-zero value if it’s a digit else it returns 0. For example, it returns a non-zero value for ‘0’ to ‘9’ and zero for others.

C library function - isdigit(), The C library function int isdigit(int c) checks if the passed character is a decimal digit character. Decimal digits are (numbers) − 0 1 2 3 4 5 6 7 8 9. Declaration. isdigit is used to check if the first character in str is a digit and therefore a valid candidate to be converted by atoi into an integer value. See also isalnum Check if character is alphanumeric (function ) isalpha Check if character is alphabetic (function )

Python Check User input is a Number or String, We can Convert string input to int or float type to check string input is an isdigit() method of string class we can check input string is number or string. and converted it to the number using int() function without any exception. Check the return value of scanf instead. isdigit is meant to determine if a character in a string is a digit. If you really wanted to use it to validate user input, then you should read the input as a string. Originally Posted by Bjarne Stroustrup (2000-10-14)

  • Welcome to Stack Overflow! Please convert the screenshot of code to formatted code in your question.
  • on which line does code crash
  • The pythonic way to do that would be to simply try it and catch any exception, instead of double checking before attempting it. I.e. try: a = int(a) except ValueError: # ask user again.
  • @TalhaIsrar it returns " Traceback (most recent call last): File "", line 14, in <module> a = int(input("podaj liczbę:")) ValueError: invalid literal for int() with base 10: 'g' " when i type g
  • Of course it wont solve the problem instead it will create a new problem. if input is not an integer code will crash
  • This is not the answer to the OP's question
  • @TalhaIsrar The post says: "i dont know how to make it check isdigit for every input."
  • This is still not the answer plz read the explaination. this should have been a comment
  • Well, that sounds interesting. I'm a newbie so, could you explain to me what do you mean by ValueError? i'm opening a code in powershell so shall i just copy there a error that occurs?
  • You'll want to learn about handling exceptions: