Check user Input is a Number or String in Python

Updated on: April 24, 2021 | 27 Comments

In this lesson, you will learn how to check user input is a number or string in Python. We will also cover how to accept numbers as input from the user. When we say a number, it means it can be integer or float.

Understand user input

Python 3 has a built-in function input() to accept user input. But it doesn’t evaluate the data received from the input() function, i.e., The input() function always converts the user input into a string and then returns it to the calling program.

python check input is a number or a string — Check input is a number or a string in Python

Let us understand this with an example.

number1 = input("Enter number and hit enter ")
print("Printing type of input value")
print("type of number ", type(number1))Code language: Python (python)

Output
Enter number and hit enter 10
Printing type of input value
type of number class 'str'

As you can see, The output shows the type of a variable as a string (str).

Solution: In such a situation, We need to convert user input explicitly to integer and float to check if it’s a number. If the input string is a number, It will get converted to int or float without exception.

Convert string input to int or float to check if it is a number

How to check if the input is a number or string in Python

Accept input from a user
Use the input() function to accept input from a user
Convert input to integer number
To check if the input string is an integer number, convert the user input to the integer type using the int() constructor.
Convert input to float number
To check if the input is a float number, convert the user input to the float type using the float() constructor.
Validate the result
If an input is an integer or float number, it can successfully get converted to int or float type. Else, we can conclude it is a string

Note: If an input is an integer or float number, it can successfully get converted to int or float, and you can conclude that entered input is a number. Otherwise, You get a valueError exception, which means the entered user input is a string.

Program :

def check_user_input(input):
    try:
        # Convert it into integer
        val = int(input)
        print("Input is an integer number. Number = ", val)
    except ValueError:
        try:
            # Convert it into float
            val = float(input)
            print("Input is a float  number. Number = ", val)
        except ValueError:
            print("No.. input is not a number. It's a string")


input1 = input("Enter your Age ")
check_user_input(input1)

input2 = input("Enter any number ")
check_user_input(input2)

input2 = input("Enter the last number ")
check_user_input(input2)Code language: Python (python)

Output

Enter your Age 28
Input is an integer number. Number =  28

Enter any number 3.14
Input is a float  number. Number =  3.14

Enter the last number 28Jessa
No.. input is not a number. It's a string

As you can see in the above output, the user has entered 28, and it gets converted into the integer type without exception.
Also, when the user entered 3.14, and it gets converted into the float type without exception.
But when the user entered a number with some character in it (28Jessa), Python raised a ValueError exception because it is not int.

Use string `isdigit()` method to check user input is number or string

Note: The isdigit() function will work only for positive integer numbers. i.e., if you pass any float number, it will not work. So, It is better to use the first approach.

Let’s execute the program to validate this.

def check_is_digit(input_str):
    if input_str.strip().isdigit():
        print("User input is Number")
    else:
        print("User input is string")


num1 = input("Enter number and hit enter")
check_is_digit(num1)

num2 = input("Enter number and hit enter")
check_is_digit(num2)
Code language: Python (python)

Output

Enter number and hit enter 45
User input is Number

Enter number and hit enter 45Jessa
User input is string

Also, If you can check whether the Python variable is a number or string, use the isinstance() function.

Example

num = 25.75
print(isinstance(num, (int, float)))
# Output True

num = '28Jessa'
print(isinstance(num, (int, float)))
# Output FalseCode language: Python (python)

Only accept a number as input

Let’s write a simple program in Python to accept only numbers input from the user. The program will stop only when the user enters the number input.

while True:
    num = input("Please enter a number ")
    try:
        val = int(num)
        print("Input is an integer number.")
        print("Input number is: ", val)
        break;
    except ValueError:
        try:
            float(num)
            print("Input is an float number.")
            print("Input number is: ", val)
            break;
        except ValueError:
            print("This is not a number. Please enter a valid number")
Code language: Python (python)

Output

Please enter a number 28Jessa
This is not a number. Please enter a valid number

Please enter a number 28
Input is an integer number.
Input number is:  28

Practice Problem: Check user input is a positive number or negative

Show Solution

user_number = input("Enter your number ")

print("\n")
try:
    val = int(user_number)
    if val > 0:
        print("User number is positive ")
    else:
        print("User number is negative ")
except ValueError:
    print("No.. input string is not a number. It's a string")Code language: Python (python)

Next Steps

Let me know your comments and feedback in the section below.

Also, Solve:

Comments

mohamed says

November 19, 2023 at 2:03 pm

input1 = input(“Enter your Age “)
check_user_input(input1)

input2 = input(“Enter any number “)
check_user_input(input2)

input2 = input(“Enter the last number “)
check_user_input(input2)

I appreciated your effort for this excellent website, and thanks allot.

I think about last inputs you mean(input3)
input3= input(“Enter the last number “)
check_user_input(input3)

Reply
KRISHNENDU DUTTA says

December 14, 2022 at 6:59 am

in the check_user_input function, if I enter any float value, then why it is not converted into an integer when “int(input)” is used………………….
please explain
I am new to python, so I am confused because I learned that if int/float/str is used, it will convert the value into integer/float/string if possible.
In the case of float value, it can be converted to an integer, but in this case, it is not converted into an integer …………
so I am really confused; please help

Reply
Hashini Madushani says

August 20, 2022 at 6:50 pm

Create a python program to input any number through the keyboard and display (print) the number. how to create this

Reply
shiva says

January 26, 2022 at 6:55 pm
```
#Write Python program which error checks if the user enters a string or not
try:
    string=input("enter the data " )
    print("data contains string")
except valueerror:
    print("data cannot contains string")
print("program ends")
```
# this program is not executing , can anybody correct this one
Reply
- Arthur says
  
  December 8, 2022 at 4:53 pm
  
  Hi, Shiva. I’m no expert and am also learning. But I can see the following problem: any value can be a string. If you type “123” in an input(), it will not consider it as a string.
  
  Now, if you try something like:
  
  try: number=int(input("enter the data: " )) print("data contains an integer") except ValueError: print("data does not contain an integer") print("program ends")
  
  You may get the expected error. Note the appropriate typing of “ValueError”, not “valueerror” (Python diferentiates that). Try using a IDE, such as VSCode, to get fast feedback for small typing errors like that.
  
  Reply
aURa says

September 29, 2021 at 6:18 pm

VERY nice. Thanks!

Reply
Bugha says

August 2, 2021 at 8:39 pm

Can you please suggest a youtube video on how to make a python game????

Reply
joy says

June 14, 2021 at 8:40 pm

How about this what is the input and output. can you help me? I just want to know how?

enter your age 60
input is an integer number, number = 60
enter any number Philippines100
No.. input is not a number. it’s a string
enter the last number 52
input is an integer number. number = 52

Reply
- daocanon says
  
  November 12, 2021 at 10:15 am
```
while True:

	age = input("enter your age :")

	try:

		val = int(age)
		print("input is an integer number","age =",age)
		break;

	except ValueError :
		print("No.. input is not a number. it’s a string")
```
  Reply

Sam williams says

May 2, 2021 at 11:12 pm

Hello, I’m working on a particular project in python and I tried looking at this lesson, but I can’t seem to find a way to apply it to my situation. I thought maybe you might know?

Program’s current objective: I need to be able to ask the user to input ‘Integer’ values for the efficiency of the vehicles rating. I also want the program to not crash if the user puts an invalid value. i.e. floating point or string value. Although I can’t seem to be able to get the program to re-ask the question until it achieves a valid answer. Then will carry on the operations from there.

def main(): 

	# This varible holds the users inputed name. 
	Name = input("Hello, what is your name?")  
	
	# This list holds the cars that will be checked out. 
	Cars = ["Car A", "Car B", "Car C", "Car D", "Car E"]
	
	# This list holds the percentage of efficiency values of Cars A - E. 
	# Which will eventually delete all but the highest value at the end of the program
	Cancel_Cars = [] 
	
	# We first need to establish the percentage value of efficiency for the cars. 
	for Car_num in range (0, len(Cars)): 
	
		# Asks user for the first time to enter an integer value for the vehicles efficiency value.
		try: 
			
			Cancel_Cars.append(int(input("Hello " + Name + ", we need you to input the efficency value of " + Cars[Car_num] + ". (PLEASE ENTER INTEGER VALUE)") ))
		
		# If the user enters the incorrect value the first time. The program will re-ask the question here.
		except ValueError:  
			
			Cancel_Cars.append(int(input("You did not enter a valid value, please try again and enter a valid value for " + Cars[Car_num] + "."))) 		
			
			
	#THIS CODE UNDER HERE IS TO TRANSVERSE THROUGH THE LOOP 
	for n in range(0, len(Cancel_Cars)): 
		print(str(Cancel_Cars[n]))

main()

Dobby says

September 9, 2021 at 6:27 pm

Please check this code:


val = ''
while type(val) != int:
    val = input("Please enter an integer value: ")
    try:
        val = int(val)
    except ValueError:
        print("No, this is not an integer value")

print("Here is the integer value: ", val)

I think this should solve your problem.

vickers says

July 3, 2020 at 3:47 am

Thank you very much this saved my game project 🙂

Reply
- Vishal says
  
  July 3, 2020 at 10:48 am
  
  You are welcome.
  
  Reply

im helpful says

June 12, 2020 at 7:47 am


print("Press 1 to convert miles to KM")
   print("Press 2 to convert KM to miles")
   print("Press 3 to convert fahrenheit to celsuis")
   print("Press 4 to convert celsuis to fahrenheit")
   print("Press 5 to leave program")
   equation = input ("which equation would you like? ")

        
   if equation =="5":
       break;
   elif equation == "1":
        num = int(input("enter a number "))
        ans = num * 1.60934;
        print("Km: " + str(ans));
   elif equation == "2":
        num = int(input("enter a number "))
        ans = num / 1.60934;
        print("Miles: " + str(ans));
   elif equation == "3":
        num = int(input("enter a number "))
        ans = (num - 32) * 5 / 9;
        print("Celsuis: " + str(ans));
   elif equation == "4":
        num = int(input("enter a number "))
        ans = num / 5 * 9 + 32;
        print("Fahrenheit: " + str(ans));

print("\n")
try:
    val = int(user_number)
    if val > 0:
        print("User number is positive ")
    else:
        print("User number is negative ")
except ValueError:
    print("No.. input string is not a number. It's a string")

Artur says

April 17, 2020 at 3:10 pm

Shouldn’t there be a:

except ValueError:
    try:
      val = float(num)
      print("Input is an float number.")
      print("Input number is: ", val)

im says

April 30, 2020 at 3:53 pm

yes, propably a miss

Reply

Mihkel says

April 9, 2020 at 11:43 am

Thank you so much. Great help!

Reply
- Vishal says
  
  April 10, 2020 at 3:56 pm
  
  You’re welcome
  
  Reply
aya farag says

December 3, 2019 at 1:17 am
#Write a Python program to check a string represent an integer or not.
```
s =input('enter a value : ')
print(type(s))
if type(s)==str:
    print(s,"The string is an integer")
else:
    print( s,"The string is not an integer")
```
why my code print always the two massage
Reply
- Vishal says
  
  December 4, 2019 at 3:51 pm
  
  It will always print two messages. first is print(type(s)) and second is from the the if-else condition.
  You typed wrong messages in the if-else block.
  
  Reply
Edward B Lipp III says

June 21, 2019 at 12:04 am
In my code, I want to enter a string. If the default type for input is a string, why do I have to put quotes around it?
python mscode.py
```
enter series of words separated by spaces: aa bb
Traceback (most recent call last):
  File "mscode.py", line 17, in main
    text = input("enter series of words separated by spaces: ")
  File "", line 1, in 
NameError: name 'a' is not defined
```
python mscode.py
enter a series of words separated by spaces: “aa bb”
This works properly. Why do I need quotes?
Reply
- Vishal says
  
  June 21, 2019 at 7:18 am
  
  Hi Edward, You don’t need to provide it in double-quotes. Can you please paste your code so I can look into it
  
  Reply

0_ace_0 says

April 5, 2019 at 4:05 am

next = input(“>”)
   if "10" in next or "11" in next or "99" in next:
         how_much=int(next)
    else:
         dead(“Man, learn to type a number”)
         exit(0)

    if how_much < 50:
		 #here you didnt have brackets
         print("Nice, you're not greedy, you win!")
         exit(0)
     else:
         dead("You greedy bastard!")

#and maybe you have as well indentation errors

Devesh says

August 6, 2020 at 7:48 pm

n= input("Number please: ")
if n.isdigit():
    how_much = int(n)
    if how_much <= 50:
        print("Nice")
    else:
        print("Greedy")
else:
    print("Please learn to write a number")

You were making it complicated, try this, this is simple. And yes, your code has too many errors like variable definition and using functions.

Disionas says

March 13, 2019 at 5:02 pm

I am trying this program on python 2.7.1:

next = raw_input(">")
    try:
        if (next.isdigit()):
            how_much=int(next)
        else:
            dead("Man, learn to type a number")
            exit(0)

    if how_much < 50:
        print "Nice, you're not greedy, you win!"
        exit(0)
    else:
        dead("You greedy bastard!")

I get the message:
if how_much < 50:
     ^
SyntaxError: invalid syntax

Can you explain to me why this happens and how I can solve it

hello says

February 4, 2019 at 12:06 pm

what if you only want letter input and no int or float?

Reply
- Vishal says
  
  February 4, 2019 at 12:57 pm
  
  Hey, Abdul use input() method without doing any explicit casing. input() method always converts user input into a string. a single char is also nothing but the string in Python.
  
  Reply

Check user Input is a Number or String in Python

Understand user input

Convert string input to int or float to check if it is a number

Use string `isdigit()` method to check user input is number or string

Only accept a number as input

Practice Problem: Check user input is a positive number or negative

Next Steps

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Understand user input

Convert string input to int or float to check if it is a number

Use string isdigit() method to check user input is number or string

Only accept a number as input

Practice Problem: Check user input is a positive number or negative

Next Steps

About Vishal

Related Tutorial Topics:

All Coding Exercises:

Python Exercises and Quizzes

Comments

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Use string `isdigit()` method to check user input is number or string