# Convert characters of a string to opposite case

• Difficulty Level : Easy
• Last Updated : 01 Dec, 2022

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++

 `// 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 ``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.

## 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

## 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`

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