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# Convert characters of a string to opposite case

Given a string, convert the characters of the string into the opposite case,i.e. if a character is the lower case then convert it into upper case and vice-versa.

Examples:

```Input : geeksForgEeks
Output : GEEKSfORGeEKS

Input : hello every one
Output : HELLO EVERY ONE```

ASCII values  of alphabets: A – Z = 65 to 90, a – z = 97 to 122

Steps:

1. Take one string of any length and calculate its length.
2. Scan string character by character and keep checking the index.
• If a character in an index is in lower case, then subtract 32 to convert it into upper case, else add 32 to convert it in lowercase
3. Print the final string.

Implementation:

## C

 `// C program to Convert characters` `// of a string to opposite case`   `#include ` `#include `   `// Function to convert characters` `// of a string to opposite case` `void` `convertOpposite(``char``* str)` `{` `    ``int` `ln = ``strlen``(str);`   `    ``// Conversion according to ASCII values` `    ``for` `(``int` `i = 0; i < ln; i++) {` `        ``if` `(str[i] >= ``'a'` `&& str[i] <= ``'z'``)` `            ``// Convert lowercase to uppercase` `            ``str[i] = str[i] - 32;` `        ``else` `if` `(str[i] >= ``'A'` `&& str[i] <= ``'Z'``)` `            ``// Convert uppercase to lowercase` `            ``str[i] = str[i] + 32;` `    ``}` `}`   `// Driver function` `int` `main()` `{` `    ``char` `str[] = ``"GeEkSfOrGeEkS"``;`   `    ``// Calling the Function` `    ``convertOpposite(str);`   `    ``printf``(``"%s"``, str);` `    ``return` `0;` `}`

## C++

 `// CPP program to Convert characters` `// of a string to opposite case` `#include ` `using` `namespace` `std;`   `// Function to convert characters` `// of a string to opposite case` `void` `convertOpposite(string& str)` `{` `    ``int` `ln = str.length();`   `    ``// Conversion according to ASCII values` `    ``for` `(``int` `i = 0; i < ln; i++) {` `        ``if` `(str[i] >= ``'a'` `&& str[i] <= ``'z'``)` `            ``// Convert lowercase to uppercase` `            ``str[i] = str[i] - 32;` `        ``else` `if` `(str[i] >= ``'A'` `&& str[i] <= ``'Z'``)` `            ``// Convert uppercase to lowercase` `            ``str[i] = str[i] + 32;` `    ``}` `}`   `// Driver function` `int` `main()` `{` `    ``string str = ``"GeEkSfOrGeEkS"``;`   `    ``// Calling the Function` `    ``convertOpposite(str);`   `    ``cout << str;` `    ``return` `0;` `}`

## Java

 `// Java program to Convert characters` `// of a string to opposite case` `class` `Test {`   `    ``// Method to convert characters` `    ``// of a string to opposite case` `    ``static` `void` `convertOpposite(StringBuffer str)` `    ``{` `        ``int` `ln = str.length();`   `        ``// Conversion using predefined methods` `        ``for` `(``int` `i = ``0``; i < ln; i++) {` `            ``Character c = str.charAt(i);` `            ``if` `(Character.isLowerCase(c))` `                ``str.replace(i, i + ``1``,` `                            ``Character.toUpperCase(c) + ``""``);` `            ``else` `                ``str.replace(i, i + ``1``,` `                            ``Character.toLowerCase(c) + ``""``);` `        ``}` `    ``}`   `    ``public` `static` `void` `main(String[] args)` `    ``{` `        ``StringBuffer str` `            ``= ``new` `StringBuffer(``"GeEkSfOrGeEkS"``);` `        ``// Calling the Method` `        ``convertOpposite(str);`   `        ``System.out.println(str);` `    ``}` `}` `// This code is contributed by Gaurav Miglani`

## Python3

 `# Python3 program to Convert characters ` `# of a string to opposite case`   `# Function to convert characters ` `# of a string to opposite case` `def` `convertOpposite(``str``):` `    ``ln ``=` `len``(``str``)`   `    ``# Conversion according to ASCII values` `    ``for` `i ``in` `range``(ln):` `        ``if` `str``[i] >``=` `'a'` `and` `str``[i] <``=` `'z'``:`   `            ``# Convert lowercase to uppercase` `            ``str``[i] ``=` `chr``(``ord``(``str``[i]) ``-` `32``)`   `        ``elif` `str``[i] >``=` `'A'` `and` `str``[i] <``=` `'Z'``:`   `            ``# Convert lowercase to uppercase` `            ``str``[i] ``=` `chr``(``ord``(``str``[i]) ``+` `32``)`   `# Driver code` `if` `__name__ ``=``=` `"__main__"``:` `    ``str` `=` `"GeEkSfOrGeEkS"` `    ``str` `=` `list``(``str``)`   `    ``# Calling the Function` `    ``convertOpposite(``str``)`   `    ``str` `=` `''.join(``str``)` `    ``print``(``str``)`   `# This code is contributed by` `# sanjeev2552`

## C#

 `// C# program to Convert characters ` `// of a string to opposite case` `using` `System;` `using` `System.Text;`   `class` `GFG{` `    `  `    ``// Method to convert characters ` `    ``// of a string to opposite case` `    ``static` `void` `convertOpposite(StringBuilder str)` `    ``{` `        ``int` `ln = str.Length;` `            `  `        ``// Conversion according to ASCII values` `        ``for` `(``int` `i=0; i=``'a'` `&& str[i]<=``'z'``)` `            `  `                ``//Convert lowercase to uppercase` `                ``str[i] = (``char``)(str[i] - 32);` `                `  `            ``else` `if``(str[i]>=``'A'` `&& str[i]<=``'Z'``)` `            `  `                ``//Convert uppercase to lowercase` `                ``str[i] = (``char``)(str[i] + 32);` `        ``}` `    ``}` `    `  `    ``// Driver code` `    ``public` `static` `void` `Main() ` `    ``{` `        ``StringBuilder str = ``new` `StringBuilder(``"GeEkSfOrGeEkS"``);` `        ``// Calling the Method` `        ``convertOpposite(str);` `        ``Console.WriteLine(str);` `        ``}` `}` `// This code is contributed by PrinciRaj1992`

## Javascript

 ``

## PHP

 `= ``'a'` `&& ``\$str``[``\$i``] <= ``'z'``){` `            ``// Convert lowercase to uppercase` `            ``\$str``[``\$i``] = ``strtoupper``(``\$str``[``\$i``]);  ` `        ``}` `        ``else` `if` `(``\$str``[``\$i``] >= ``'A'` `&& ``\$str``[``\$i``] <= ``'Z'``){` `            ``// Convert uppercase to lowercase` `            ``\$str``[``\$i``] = ``strtolower``(``\$str``[``\$i``]); ` `        ``}` `    ``} ` `  ``return` `\$str``;` `}`   `// Driver function` `\$str` `= ``"GeEkSfOrGeEkS"``;`   `    ``// Calling the Function` `echo``(convertOpposite(``\$str``));` `  `  `// This code is contributed by ksrikanth0498` `  `  `?>`

Output

`gEeKsFoRgEeKs`

Time Complexity: O(n)

Note: This program can alternatively be done using C++ inbuilt functions – Character.toLowerCase(char) and Character.toUpperCase(char).

Approach 2: The problem can be solved using letter case toggling. Follow the below steps to solve the problem:

• Traverse the given string S.
• For each character, Si, do Si =  Si ^ (1 << 5).
• Si ^ (1 << 5) toggles the 5th bit which means 97 will become 65 and 65 will become 97:
• 65 ^ 32 = 97
• 97 ^ 32 = 65
• Print the string after all operations

Below is the implementation of the above approach:

## C

 `// C program to toggle all characters`   `#include ` `#include `   `// Function to toggle characters` `void` `toggleChars(``char``* S)` `{` `    ``while` `(*S) {` `        ``if` `(``isalpha``(*S)) {` `            ``*S ^= (1 << 5);` `        ``}` `        ``++S;` `    ``}` `}`   `// Driver code` `int` `main()` `{` `    ``char` `S[] = ``"GeKf@rGeek\$"``;` `    ``toggleChars(S);` `    ``printf``(``"String after toggle:\n%s\n"``, S);` `    ``return` `0;` `}`

## C++

 `// C++ program to toggle all characters` `#include ` `using` `namespace` `std;`   `// Function to toggle characters` `void` `toggleChars(string& S)` `{` `    ``for` `(``auto``& it : S) {` `        ``if` `(``isalpha``(it)) {` `            ``it ^= (1 << 5);` `        ``}` `    ``}` `}`   `// Driver code` `int` `main()` `{` `    ``string S = ``"GeKf@rGeek\$"``;` `    ``toggleChars(S);` `    ``cout << ``"String after toggle "` `<< endl;` `    ``cout << S << endl;` `    ``return` `0;` `}`   `// Code contributed by koulick_sadhu`

## Java

 `// Java program to toggle all characters` `import` `java.util.*;`   `class` `GFG {`   `    ``static` `char``[] S = ``"GeKf@rGeek\$"``.toCharArray();`   `    ``// Function to toggle characters` `    ``static` `void` `toggleChars()` `    ``{` `        ``for` `(``int` `i = ``0``; i < S.length; i++) {` `            ``if` `(Character.isAlphabetic(S[i])) {` `                ``S[i] ^= (``1` `<< ``5``);` `            ``}` `        ``}` `    ``}`   `    ``// Driver code` `    ``public` `static` `void` `main(String[] args)` `    ``{` `        ``toggleChars();` `        ``System.out.print(``"String after toggle "` `                         ``+ ``"\n"``);` `        ``System.out.print(String.valueOf(S));` `    ``}` `}`   `// This code is contributed by Amit Katiyar`

## Python3

 `# python program for the same approach` `def` `isalpha(``input``):` `    ``input_char ``=` `ord``(``input``[``0``])`   `    ``# CHECKING FOR ALPHABET` `    ``if``((input_char >``=` `65` `and` `input_char <``=` `90``) ``or` `(input_char >``=` `97` `and` `input_char <``=` `122``)):` `        ``return` `True` `    ``else``:` `        ``return` `False`   `# Function to toggle characters`     `def` `toggleChars(S):` `    ``s ``=` `""`   `    ``for` `it ``in` `range``(``len``(S)):`   `        ``if``(isalpha(S[it])):` `            ``s ``+``=` `chr``(``ord``(S[it]) ^ (``1` `<< ``5``))` `        ``else``:` `            ``s ``+``=` `S[it]`   `    ``return` `s`     `# Driver code` `S ``=` `"GeKf@rGeek\$"` `print``(f``"String after toggle {toggleChars(S)}"``)`   `# This code is contributed by shinjanpatra`

## C#

 `// C# program to toggle all characters` `using` `System;`   `class` `GFG {`   `    ``static` `char``[] S = ``"GeKf@rGeek\$"``.ToCharArray();`   `    ``// Function to toggle characters` `    ``static` `void` `toggleChars()` `    ``{` `        ``for` `(``int` `i = 0; i < S.Length; i++) {` `            ``if` `(``char``.IsLetter(S[i])) {` `                ``S[i] = (``char``)((``int``)(S[i]) ^ (1 << 5));` `            ``}` `        ``}` `    ``}`   `    ``// Driver code` `    ``public` `static` `void` `Main(String[] args)` `    ``{` `        ``toggleChars();` `        ``Console.Write(``"String after toggle "` `                      ``+ ``"\n"``);` `        ``Console.Write(String.Join(``""``, S));` `    ``}` `}`   `// This code is contributed by Princi Singh`

## Javascript

 ``   `// This code is contributed by Akshit Saxena`

Output

```String after toggle
gEkF@RgEEK\$```

Time Complexity: O(n)

This article is contributed by Rishabh Jain. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Approach : Using isupper() and islower(),upper() and lower().

Initialize an empty string.Iterate a for loop over the given string and check each character whether is lowercase or uppercase using isupper() and islower().If lowercase converts the character to uppercase using upper() and append to empty string, similarly with uppercase.

## C

 `// C program to Convert characters` `// of a string to opposite case`   `#include ` `#include ` `#include `   `int` `main()` `{` `    ``char` `str[] = ``"GeEkSfOrGeEkS"``;` `    ``char` `x[100];` `    ``for` `(``int` `i = 0; i < ``strlen``(str); i++) {` `        ``char` `ch = str[i];` `        ``if` `(``isupper``(ch))` `            ``x[i] = ``tolower``(ch);` `        ``else` `            ``x[i] = ``toupper``(ch);` `    ``}` `    ``x[``strlen``(str)] = ``'\0'``;` `    ``printf``(``"%s\n"``, x);` `    ``return` `0;` `}`

## C++

 `// C++ program to Convert characters` `// of a string to opposite case`   `#include ` `using` `namespace` `std;`   `int` `main()` `{`   `    ``string str = ``"GeEkSfOrGeEkS"``;` `    ``string x = ``""``;` `    ``for` `(``int` `i = 0; i < str.length(); i++) {` `        ``char` `ch = str[i];` `        ``if` `(``isupper``(ch))` `            ``x += ``tolower``(ch);` `        ``else` `            ``x += ``toupper``(ch);` `    ``}` `    ``cout << x << endl;` `    ``return` `0;` `}`   `// This code is contributed by lokeshmvs21.`

## Java

 `// Java program to Convert characters` `// of a string to opposite case` `import` `java.io.*;`   `class` `GFG {` `  ``public` `static` `void` `main(String[] args)` `  ``{` `    ``String str = ``"GeEkSfOrGeEkS"``;` `    ``String x = ``""``;` `    ``for` `(``int` `i = ``0``; i < str.length(); i++) {` `      ``char` `ch = str.charAt(i);` `      ``if` `(Character.isUpperCase(ch))` `        ``x += Character.toLowerCase(ch);` `      ``else` `        ``x += Character.toUpperCase(ch);` `    ``}` `    ``System.out.println(x);` `  ``}` `}`   `// This code is contributed by karandeep1234.`

## Python3

 `# Python3 program to Convert characters` `# of a string to opposite case`   `str` `=` `"GeEkSfOrGeEkS"` `x``=``""` `for` `i ``in` `str``:` `    ``if``(i.isupper()):` `        ``x``+``=``i.lower()` `    ``else``:` `        ``x``+``=``i.upper()` `print``(x)`

## C#

 `// C# program to Convert characters` `// of a string to opposite case` `using` `System;`   `public` `class` `GFG {`   `  ``static` `public` `void` `Main()` `  ``{`   `    ``// Code` `    ``string` `str = ``"GeEkSfOrGeEkS"``;` `    ``string` `x = ``""``;` `    ``for` `(``int` `i = 0; i < str.Length; i++) {` `      ``char` `ch = str[i];` `      ``if` `(Char.IsUpper(ch)) {` `        ``x += Char.ToLower(ch);` `      ``}` `      ``else` `{` `        ``x += Char.ToUpper(ch);` `      ``}` `    ``}` `    ``Console.WriteLine(x);` `  ``}` `}`   `// This code is contributed by lokeshmvs21.`

## Javascript

 `// Javascript program to Convert characters` `// of a string to opposite case` ` `  `    ``let str = ``"GeEkSfOrGeEkS"``;` `    ``let x = ``""``;` `    ``for` `(let i = 0; i < str.length; i++) {` `      ``let ch = str[i];` `      ``if``(str.charAt(i) === str.charAt(i).toUpperCase())` `        ``x += str.charAt(i).toLowerCase(ch);` `      ``else` `        ``x += str.charAt(i).toUpperCase(ch);` `    ``}` `    ``console.log(x);` `    `  `    ``// This code is contributed by garg28harsh.`

Output

`gEeKsFoRgEeKs`

Approach : Using index() method

## C

 `// C program to Convert characters` `// of a string to opposite case` `#include ` `#include `   `int` `main()` `{` `    ``char` `str[] = ``"GeEkSfOrGeEkS"``;` `    ``char` `x[100] = ``""``;` `    ``char` `upperalphabets[] = ``"ABCDEFGHIJKLMNOPQRSTUVWXYZ"``;` `    ``char` `loweralphabets[] = ``"abcdefghijklmnopqrstuvwxyz"``;` `    ``int` `i, j;` `    ``for` `(i = 0; i < ``strlen``(str); i++) {` `        ``char` `ch = str[i];` `        ``if` `(``strchr``(upperalphabets, ch)) {` `            ``j = ``strchr``(upperalphabets, ch) - upperalphabets;` `            ``x[i] = loweralphabets[j];` `        ``}` `        ``else` `{` `            ``j = ``strchr``(loweralphabets, ch) - loweralphabets;` `            ``x[i] = upperalphabets[j];` `        ``}` `    ``}` `    ``printf``(``"%s\n"``, x);` `    ``return` `0;` `}`

## C++

 `// C++ program to Convert characters` `// of a string to opposite case` `#include ` `using` `namespace` `std;`   `int` `main()` `{` `    ``string str = ``"GeEkSfOrGeEkS"``;` `    ``string x = ``""``;` `    ``string upperalphabets = ``"ABCDEFGHIJKLMNOPQRSTUVWXYZ"``;` `    ``string loweralphabets = ``"abcdefghijklmnopqrstuvwxyz"``;` `    ``for` `(``int` `i = 0; i < str.length(); i++) {` `        ``char` `ch = str[i];` `        ``if` `(upperalphabets.find(ch) != -1) {` `            ``x += loweralphabets[upperalphabets.find(ch)];` `        ``}` `        ``else` `{` `            ``x += upperalphabets[loweralphabets.find(ch)];` `        ``}` `    ``}` `    ``cout << x << endl;` `    ``return` `0;` `}` `// This code is contributed by Prajwal Kandekar`

## Java

 `// Java program to Convert characters` `// of a string to opposite case`   `public` `class` `GFG {` `  ``public` `static` `void` `main(String[] args)` `  ``{` `    ``String str = ``"GeEkSfOrGeEkS"``;` `    ``String x = ``""``;` `    ``String upperalphabets` `      ``= ``"ABCDEFGHIJKLMNOPQRSTUVWXYZ"``;` `    ``String loweralphabets` `      ``= ``"abcdefghijklmnopqrstuvwxyz"``;` `    ``for` `(``int` `i = ``0``; i < str.length(); i++) {` `      ``char` `ch = str.charAt(i);` `      ``if` `(upperalphabets.indexOf(ch) != -``1``) {` `        ``x += loweralphabets.charAt(` `          ``upperalphabets.indexOf(ch));` `      ``}` `      ``else` `{` `        ``x += upperalphabets.charAt(` `          ``loweralphabets.indexOf(ch));` `      ``}` `    ``}` `    ``System.out.println(x);` `  ``}` `}`   `// This Code is contributed by karandeep1234`

## Python3

 `# Python3 program to Convert characters` `# of a string to opposite case`   `str` `=` `"GeEkSfOrGeEkS"` `x``=``""` `upperalphabets``=``"ABCDEFGHIJKLMNOPQRSTUVWXYZ"` `loweralphabets``=``"abcdefghijklmnopqrstuvwxyz"` `for` `i ``in` `str``:` `    ``if` `i ``in` `upperalphabets:` `        ``x``+``=``loweralphabets[upperalphabets.index(i)]` `    ``else``:` `        ``x``+``=``upperalphabets[loweralphabets.index(i)]` `print``(x)`

## C#

 `// C# program to Convert characters` `// of a string to opposite case` `using` `System;`   `public` `class` `GFG {` `  ``public` `static` `void` `Main(``string``[] args)` `  ``{` `    ``string` `str = ``"GeEkSfOrGeEkS"``;` `    ``string` `x = ``""``;` `    ``string` `upperalphabets` `      ``= ``"ABCDEFGHIJKLMNOPQRSTUVWXYZ"``;` `    ``string` `loweralphabets` `      ``= ``"abcdefghijklmnopqrstuvwxyz"``;` `    ``for` `(``int` `i = 0; i < str.Length; i++) {` `      ``char` `ch = str[i];` `      ``if` `(upperalphabets.IndexOf(ch) != -1) {` `        ``x += loweralphabets[upperalphabets.IndexOf(` `          ``ch)];` `      ``}` `      ``else` `{` `        ``x += upperalphabets[loweralphabets.IndexOf(` `          ``ch)];` `      ``}` `    ``}` `    ``Console.WriteLine(x);` `  ``}` `}`   `// This Code is contributed by karandeep1234`

## Javascript

 `// Javascript program to Convert characters` `// of a string to opposite case`     `    ``let str = ``"GeEkSfOrGeEkS"``;` `    ``let x = ``""``;` `    ``let upperalphabets` `      ``= ``"ABCDEFGHIJKLMNOPQRSTUVWXYZ"``;` `    ``let loweralphabets` `      ``= ``"abcdefghijklmnopqrstuvwxyz"``;` `    ``for` `(let i = 0; i < str.length; i++) {` `      ``let ch = str[i];` `      ``if` `(upperalphabets.indexOf(ch) != -1) {` `        ``x += loweralphabets[upperalphabets.indexOf(ch)];` `      ``}` `      ``else` `{` `        ``x += upperalphabets[loweralphabets.indexOf(ch)];` `      ``}` `    ``}` `    ``console.log(x);`   `// This code is contributed by garg28harsh.`

Output

`gEeKsFoRgEeKs`

Another Approach:-

• In this approach we will use transform function
• What transform function do is that it convert the case of a string into upper case or lower case without using any other extra space or string.
• In this approach we will just traverse the string and check the case of the character.
• If the character is in upper case then we will use transform function to convert it into lower case.
• else we will convert in into upper case
• Below is the implementation of the above approach.

Implementation:-

## C

 `// C program to Convert characters` `// of a string to opposite case`   `#include ` `#include ` `#include `   `int` `main()` `{` `    ``char` `str[] = ``"GeEkSfOrGeEkS"``;` `    ``int` `len = ``strlen``(str);` `    ``for` `(``int` `i = 0; i < len; i++) {` `        ``if` `(``isupper``(str[i])) {` `            ``str[i] = ``tolower``(str[i]);` `        ``}` `        ``else` `{` `            ``str[i] = ``toupper``(str[i]);` `        ``}` `    ``}` `    ``printf``(``"%s\n"``, str);` `    ``return` `0;` `}`

## C++

 `// C++ program to Convert characters` `// of a string to opposite case` `#include ` `using` `namespace` `std;` `int` `main()` `{` `    ``string str = ``"GeEkSfOrGeEkS"``;` `    ``for` `(``int` `i = 0; i < str.length(); i++) {` `          ``if``(``isupper``(str[i])){` `              ``transform(str.begin()+i, str.begin()+i+1, str.begin()+i, ::``tolower``);` `        ``}` `        ``else``{` `              ``transform(str.begin()+i, str.begin()+i+1, str.begin()+i, ::``toupper``);` `        ``}` `    ``}` `    ``cout << str << endl;` `    ``return` `0;` `}` `// This code is contributed by shubhamrajput6156`

## Java

 `import` `java.util.*;`   `public` `class` `Main {` `    ``public` `static` `void` `main(String[] args) {` `        ``String str = ``"GeEkSfOrGeEkS"``;` `        ``StringBuilder sb = ``new` `StringBuilder(str);` `        `  `        ``for` `(``int` `i = ``0``; i < sb.length(); i++) {` `            ``if` `(Character.isUpperCase(sb.charAt(i))) {` `                ``sb.setCharAt(i, Character.toLowerCase(sb.charAt(i)));` `            ``} ``else` `{` `                ``sb.setCharAt(i, Character.toUpperCase(sb.charAt(i)));` `            ``}` `        ``}` `        `  `        ``str = sb.toString();` `        ``System.out.println(str);` `    ``}` `}`

## Python3

 `# Python program to Convert characters` `# of a string to opposite case`   `str` `=` `"GeEkSfOrGeEkS"`   `for` `i ``in` `range``(``len``(``str``)):` `    ``if` `str``[i].isupper():` `        ``str` `=` `str``[:i] ``+` `str``[i].lower() ``+` `str``[i``+``1``:]` `    ``else``:` `        ``str` `=` `str``[:i] ``+` `str``[i].upper() ``+` `str``[i``+``1``:]`   `print``(``str``)`

## C#

 `// C# program to Convert characters` `// of a string to opposite case` `using` `System;`   `class` `GFG {` `    ``public` `static` `void` `Main() {` `        ``string` `str = ``"GeEkSfOrGeEkS"``;` `      ``for` `(``int` `i = 0; i < str.Length; i++) {` `          ``// If the character is upper case, convert it to lower case` `          ``if` `(Char.IsUpper(str[i])) {` `          ``str = str.Remove(i, 1).Insert(i, Char.ToLower(str[i]).ToString());` `      ``}` `      ``// If the character is lower case, convert it to upper case` `      ``else` `{` `          ``str = str.Remove(i, 1).Insert(i, Char.ToUpper(str[i]).ToString());` `      ``}` `    ``}` `    ``Console.WriteLine(str);` `    ``}` `}`

## Javascript

 `let str = ``"GeEkSfOrGeEkS"``;` `for` `(let i = 0; i < str.length; i++) {` `  ``if` `(str[i] === str[i].toUpperCase()) {` `    ``str = str.slice(0, i) + str[i].toLowerCase() + str.slice(i + 1);` `  ``} ``else` `{` `    ``str = str.slice(0, i) + str[i].toUpperCase() + str.slice(i + 1);` `  ``}` `}` `console.log(str);`   `// THIS CODE IS CONTRIBUTED BY CHANDAN AGARWAL`

Output

`gEeKsFoRgEeKs`

Time Complexity:- O(N) Where N is length of String

Auxiliary Space:- O(1)

Another Approach:

In this implementation, we initialize a pointer p to the start of the string str. We then use a while loop to iterate through the string by checking if the character p points to is the null character (‘\0’). Inside the loop, we use the same logic as the previous implementation, but instead of accessing the array element at index i, we use the dereference operator * to access the value that p points to. After updating the character at the current position, we increment the pointer p to point to the next character in the string.

## C++

 `#include ` `#include ` `#include `   `int` `main()` `{` `    ``char` `str[] = ``"GeEkSfOrGeEkS"``;` `    ``char``* p = str;  ``// initialize pointer to start of string` `    ``while` `(*p != ``'\0'``) {` `        ``if` `(``isupper``(*p)) {` `            ``*p = ``tolower``(*p);` `        ``}` `        ``else` `{` `            ``*p = ``toupper``(*p);` `        ``}` `        ``p++;  ``// move pointer to next character` `    ``}` `    ``printf``(``"%s\n"``, str);` `    ``return` `0;` `}`

Output

```gEeKsFoRgEeKs
```

Time Complexity:- O(n) Where N is length of input String

Auxiliary Space:- O(1)

My Personal Notes arrow_drop_up