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Python – Every Kth Strings Uppercase
• Last Updated : 05 Sep, 2020

Given a String list, change every Kth string to uppercase.

Input : test_list = [“gfg”, “is”, “best”, “for”, “geeks”], K = 3
Output : [‘GFG’, ‘is’, ‘best’, ‘FOR’, ‘geeks’]
Explanation : All Kth strings are uppercased.

Input : test_list = [“gfg”, “is”, “best”, “for”, “geeks”], K = 4
Output : [‘GFG’, ‘is’, ‘best’, ‘for’, ‘GEEKS’]
Explanation : All Kth strings are uppercased.

Method #1 : Using loop + upper()

In this, we iterate for all strings using loop and upper is used to perform uppercase, Kth index is detected using modulo operator.

## Python3

 `# Python3 code to demonstrate working of  ` `# Every Kth Strings Uppercase ` `# Using loop + upper() ` ` `  `# initializing list ` `test_list ``=` `[``"gfg"``, ``"is"``, ``"best"``, ``"for"``, ``"geeks"``, ``"and"``, ``"CS"``]  ` ` `  `# printing original list ` `print``(``"The original list is : "` `+` `str``(test_list)) ` ` `  `# initializing K  ` `K ``=` `3` ` `  `res ``=` `[] ` `for` `idx ``in` `range``(``len``(test_list)): ` `     `  `    ``# checking for Kth index ` `    ``if` `idx ``%` `K ``=``=` `0``: ` `        ``res.append(test_list[idx].upper()) ` `    ``else` `: ` `        ``res.append(test_list[idx]) ` ` `  `# printing result  ` `print``(``"The resultant String list : "` `+` `str``(res))`

Output

```The original list is : ['gfg', 'is', 'best', 'for', 'geeks', 'and', 'CS']
The resultant String list : ['GFG', 'is', 'best', 'FOR', 'geeks', 'and', 'CS']
```

Method #2 : Using list comprehension

This yet another way in which this task can be performed. In this we use list comprehension as shorthand, performs tasks similar to above method.

## Python3

 `# Python3 code to demonstrate working of  ` `# Every Kth Strings Uppercase ` `# Using list comprehension ` ` `  `# initializing list ` `test_list ``=` `[``"gfg"``, ``"is"``, ``"best"``, ``"for"``, ``"geeks"``, ``"and"``, ``"CS"``]  ` ` `  `# printing original list ` `print``(``"The original list is : "` `+` `str``(test_list)) ` ` `  `# initializing K  ` `K ``=` `3` ` `  `# shorthand to perform this task ` `res ``=` `[test_list[idx].upper() ``if` `idx ``%` `K ``=``=` `0` `else` `test_list[idx] ` `       ``for` `idx ``in` `range``(``len``(test_list))] ` ` `  `# printing result  ` `print``(``"The resultant String list : "` `+` `str``(res)) `

Output

```The original list is : ['gfg', 'is', 'best', 'for', 'geeks', 'and', 'CS']
The resultant String list : ['GFG', 'is', 'best', 'FOR', 'geeks', 'and', 'CS']
```

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