# 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 casevoid 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 functionint main(){    string str = "GeEkSfOrGeEkS";     // Calling the Function    convertOpposite(str);     cout << str;    return 0;}

## Java

 // Java program to Convert characters// of a string to opposite caseclass 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 casedef 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 codeif __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 caseusing 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



## 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 Functionecho(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 charactersvoid toggleChars(string& S){    for (auto& it : S) {        if (isalpha(it)) {            it ^= (1 << 5);        }    }} // Driver codeint 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 charactersimport 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 approachdef 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 codeS = "GeKf@rGeek\$"print(f"String after toggle {toggleChars(S)}") # This code is contributed by shinjanpatra

## C#

 // C# program to toggle all charactersusing 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)

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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 caseimport 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 caseusing 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 caseusing 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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