Python how to only accept numbers as a input

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mark= eval(raw_input("What is your mark?"))
try:
    int(mark)
except ValueError:
    try:
        float(mark)
    except ValueError:
        print "This is not a number"

So I need to make a python program that looks at your mark and gives you varying responses depending on what it is.

However I also need to add a way to stop random text which isn't numbers from being entered into the program.

I thought I had found a solution to this but it won't make it it past the first statement to the failsafe code that is meant to catch it if it was anything but numbers.

So pretty much what happens is if I enter hello instead of a number it fails at the first line and gives me back an error that says exceptions:NameError: name 'happy' is not defined.

How can I change it so that it can make it to the code that gives them the print statement that they need to enter a number?

remove eval and your code is correct:

mark = raw_input("What is your mark?")
try:
    int(mark)
except ValueError:
    try:
        float(mark)
    except ValueError:
        print "This is not a number"

Just checking for a float will work fine:

try:
    float(mark)
except ValueError:
    print "This is not a number"

Python Check User input is a Number or String, Approach Two: use string class isdigit() method to check user input is number or string. Note: isdigit() function will work only for positive integer numbers. i.e., if you pass any float number, it will say it is a string. Let's execute the above program again to validate it. Output: How the input function works in Python : When input() function executes program flow will be stopped until the user has given an input.; The text or message display on the output screen to ask a user to enter input value is optional i.e. the prompt, will be printed on the screen is optional.

You can simply cae to float or int and catch the exception (if any). Youre using eval which is considered poor and you add a lot of redundant statements.

try:
    mark= float(raw_input("What is your mark?"))
except ValueError:
    print "This is not a number"

"Why not use eval?" you ask, well... Try this input from the user: [1 for i in range (100000000)]

Python Tip: Validating user input as number (Integer), To use them as integers you will need to convert the user input into an integer using the int() function. e.g. age=int(input("What is your age?")) This line of code would work fine as long as the user enters an integer. Python Read Input Integer. The upper example is no restrictions on input type data. So what if you want only read Integer type value from the console. You have to put int() function around the input function. Here is an example of adding tow numbers of given by users.

you can use the String object method called isnumeric. it's more efficient than try- except method. see the below code.

def getInput(prompt):
    value = input(prompt)
    while not value.isnumeric():
        print("enter a number")
        value = input("enter again")
    return int(value)

How to make sure my code allows the user to input only numbers in , There's a number of ways to do this, depending on your application and how How do I make sure my code allows the user to input only numbers in python? In most of your Python programs you will want to interact with the end-user by asking questions and retrieving user inputs. To do so you can use the input() function: e.g. Sometimes you will need to retrieve numbers. Whole numbers (numbers with no decimal place) are called integers. To use them as integers you will need to convert the user input into an integer using the int() function. e.g

import re

pattern = re.compile("^[0-9][0-9]\*\\.?[0-9]*")

status = re.search(pattern, raw_input("Enter the Mark : "))

if not status:

        print "Invalid Input"

How to accept only integer or float inputs? : learnpython, My current code accepts integers that are greater than 0, which is what I want, but I also want to accept floats/decimals as well. How would I do … Python Server Side Programming Programming Python 3.x has an in-built input() function to accept user input. This input() function returns a string data and it can be stored in string variable.

Actually if you going to use eval() you have to define more things.

acceptables=[1,2,3,4,5,6,7,8,9,0,"+","*","/","-"]
try:
    mark= eval(int(raw_input("What is your mark?")))
except ValueError:
    print ("It's not a number!")
if mark not in acceptables:
    print ("You cant do anything but arithmetical operations!")

It's a basically control mechanism for eval().

How You Make Sure input() Is the Type You Want It to Be in Python , In Python, you can ask for user input with the function input() : a function that calculates the area of a rectangle — but it only accepts integers� Python how to only accept numbers as a input. Ask Question Asked 5 years, 7 months ago. Active 6 months ago. A simple program to accept only numbers. 2.

How can I limit the user input to only integers in Python, Python input only allow numbers. How to make sure my code allows the user to input only numbers in , remove eval and your code� User Input. Python allows for user input. That means we are able to ask the user for input. The method is a bit different in Python 3.6 than Python 2.7. Python 3.6 uses the input() method. Python 2.7 uses the raw_input() method. The following example asks for the username, and when you entered the username, it gets printed on the screen:

Input, print and numbers - Learn Python 3, There exists a function, print() , to output data from any Python program. To use it, pass it returns only the quotient of the division (i.e. no remainder). print(37 Let's try to write a program that inputs two numbers and prints their sum. We read � Accept List as an Input from a user in Python. Like string and integer, we can also accept list and array as an input from a user. For example, accept a list of numbers from the user.

Chapter 8 – Input Validation, If the withdrawFromAccount() function subtracts a negative number from the Also, you may miss certain cases and allow invalid input to pass through your checks is outside of an intended range, PyInputPlus will reprompt them for input just�

Comments
  • don't use eval
  • Why do you even need eval in this code? It should work as it is without it.
  • Try using the assert or isInstance
  • @Bogdan because user can put command, e.g. rm -rf / using system command in python, and if python runs with root privileges, big problem.
  • @Marcin: this is a concern if he uses eval, and my comment says that he does not need to use it.
  • no worries, you're welcome, really be careful with eval, there is very rarely a good reason to use it