# Python – Replace all numbers by K in given String

• Last Updated : 05 Sep, 2020

Given a string containing numbers, replace each number by K.

Input : test_str = ‘G4G is 4 all No. 1 Geeks’, K = ‘#’
Output : G#G is # all No. # Geeks
Explanation : All numbers replaced by K.

Input : test_str = ‘G4G is 4 all No. Geeks’, K = ‘#’
Output : G#G is # all No. Geeks
Explanation : All numbers replaced by K.

Method #1 : Using replace() + isdigit()

In this, we check for numerics using isdigit() and replace() is used to perform the task of replacing the numbers by K.

## Python3

 `# Python3 code to demonstrate working of ``# Replace numbers by K in String``# Using replace() + isdigit()`` ` `# initializing string``test_str ``=` `'G4G is 4 all No. 1 Geeks'`` ` `# printing original string``print``(``"The original string is : "` `+` `str``(test_str))`` ` `# initializing K ``K ``=` `'@'`` ` `# loop for all characters``for` `ele ``in` `test_str:``    ``if` `ele.isdigit():``        ``test_str ``=` `test_str.replace(ele, K)``         ` `# printing result ``print``(``"The resultant string : "` `+` `str``(test_str)) `
Output
```The original string is : G4G is 4 all No. 1 Geeks
The resultant string : G@G is @ all No. @ Geeks
```

Method #2 : Using regex() + sub()

In this, appropriate regex is used to identify digits and sub() is used to perform replace.

## Python3

 `# Python3 code to demonstrate working of ``# Replace numbers by K in String``# Using regex() + sub()``import` `re`` ` `# initializing string``test_str ``=` `'G4G is 4 all No. 1 Geeks'`` ` `# printing original string``print``(``"The original string is : "` `+` `str``(test_str))`` ` `# initializing K ``K ``=` `'@'`` ` `# using regex expression to solve problem ``res ``=` `re.sub(r``'\d'``, K, test_str)``         ` `# printing result ``print``(``"The resultant string : "` `+` `str``(res)) `
Output
```The original string is : G4G is 4 all No. 1 Geeks
The resultant string : G@G is @ all No. @ Geeks
```

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