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Python program to check whether a string contains a number or not

Python isdigit() function example: Here, we are going to learn how to check whether a string contains only digits or not i.e. string contains only number or not? By IncludeHelp Last updated : February 25, 2024

Problem statement

Given a string and we have to check whether it contains only digits or not in Python.

Example

Input:
str1 = "8789"
str2 = "Hello123"
str3 = "123Hello"
str4 = "123 456" #contains space 

# function call
str1.isdigit()
str2.isdigit()
str3.isdigit()
str4.isdigit()

Output:
True
False
False
False

Checking string contains a number or not

To check that a string contains only digits (or a string has a number) – we can use isdigit() function, it returns true, if all characters of the string are digits.

Syntax

string.isdigit()

Python code to check whether a strings contains a number or not

# python program to check whether a string 
# contains only digits or not 

# variables declaration & initializations
str1 = "8789"
str2 = "Hello123"
str3 = "123Hello"
str4 = "123 456"    #contains space 

# checking
print("str1.isdigit(): ", str1.isdigit())
print("str2.isdigit(): ", str2.isdigit())
print("str3.isdigit(): ", str3.isdigit())
print("str4.isdigit(): ", str4.isdigit())

# checking & printing messages
if str1.isdigit():
    print("str1 contains a number")
else:
    print("str1 does not contain a number")

if str2.isdigit():
    print("str2 contains a number")
else:
    print("str2 does not contain a number")

if str3.isdigit():
    print("str3 contains a number")
else:
    print("str3 does not contain a number")

if str4.isdigit():
    print("str4 contains a number")
else:
    print("str4 does not contain a number")

Output

str1.isdigit():  True
str2.isdigit():  False
str3.isdigit():  False
str4.isdigit():  False
str1 contains a number
str2 does not contain a number
str3 does not contain a number
str4 does not contain a number

To understand the above program, you should have the basic knowledge of the following Python topics:

• Python print() Method
• Python Variables
• Python Conditional Statements
• Python Strings

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