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Python | Check if the string contains only numbers or not

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Method # 1: Using the isdigit Method()

# Python3 demo code
# how to check if a string contains
# only numbers or not

 
# Initializing string

ini_string1 = ’1234556’

ini_string2 = ’ab123bc’

  
# print the original line

print ( "Initial Strings:" , ini_string1, ini_string2)

  
# Using isdigit ()

if ini_string1.isdigit ():

print ( "String1 contains all numbers" )

else :

print ( "String1 doesn’t contains all numbers" )

 

if ini_string2.isdigit ():

print ( "String2 conatins all numbers" )

else :

print ( " String2 doesn’t contains all numbers " )

Exit:

 Initial Strings : 1234556 ab123bc String1 contains all numbers String2 doesn’t contains all numbers 

Method # 2: Using Regular Expressions

# Python3 demo code
# how to check if a string contains
# only numbers or not

import re

 
# Initialization string

i ni_string1 = ’1234556’

ini_string2 = ’ab123bc’

  
# print the original line

print ( "Initial Strings:" , ini_string1, ini_string2)

  
# Using regex ()

if re.match ( ’^ [0-9] * $’ , ini_string1):

print ( "String1 contains all numbers" )

else :

  print ( "String1 doesn’t contains all numbers" )

  

if re.match ( ’ ^ [0-9] * $ ’ , ini_string2):

  print ( "String2 conatins all numbers" )

else :

print ( "String2 doesn’ t contains all numbers " )

Output:

 Initial Strings: 1234556 ab123bc String 1 contains all numbers String2 doesn’t contains all numbers 

Method # 3: Using try / exception

# Python3 demo code
# how to check if a string contains
# only numbers or not

 
# Initializing string

ini_string1 = ’1234556’

ini_string2 = ’abc123’

 
# print the original line

print ( "Initial Strings:" , ini_string1, ini_string2)

  
# Using try / exception:

try :

num = int (ini_string1)

  print ( "String1 contains only digits" )

except :

  print ( "String1 doesn’tcontains only digits" )

 

try :

  num = int (ini_string2)

print ( "String2 contains only digits" )

except :

print ( "String2 doesn’t contains only digits" )

 

Output :

 Initial Strings: 1234556 abc123 String1 contains only digits String2 doesn’t contains only digits 

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