Python program to replace every Nth character in String

Given a string, the task is to write a Python program to replace every Nth character in a string by the given value K.

Examples:

Input : test_str = “geeksforgeeks is best for all geeks”, K = ‘$’, N = 5

Output : geeks$orge$ks i$ bes$ for$all $eeks

Explanation : Every 5th character is converted to $.

Input : test_str = “geeksforgeeks is best for all geeks”, K = ‘*’, N = 5

Output : geeks*orge*ks i* bes* for*all *eeks

Explanation : Every 5th occurrence is converted to *.

Method 1 : Using loop and enumerate()

In this, we perform an iteration of each character and check if its Nth by performing modulo, i.e finding remainder by N. If its Nth occurrence, the character is replaced by K.

Example

Output:

The original string is : geeksforgeeks is best for all geeks

String after replacement : geeks$orge$ks i$ bes$ for$all $eeks

Method 2 : Using generator expression, join() and enumerate()

In this, the construction of string happens using join(). The enumerate(), helps to get required indices. The generator expression provides a shorthand approach to this problem.

Example

Output:

The original string is : geeksforgeeks is best for all geeks

String after replacement : geeks$orge$ks i$ bes$ for$all $eeks