Convert characters of a string to opposite case
Last Updated :
17 Oct, 2023
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:
- Take one string of any length and calculate its length.
- 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
- Print the final string.
Implementation:
C++
// CPP program to Convert characters
// of a string to opposite case
#include <iostream>
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;
}
// C program to Convert characters
// of a string to opposite case
#include <stdio.h>
#include <string.h>
// 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;
}
// 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 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# 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<ln; i++)
{
if (str[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
<script>
// Function to convert characters
// of a string to opposite case
function convertOpposite(str)
{
var ln = str.length;
// Conversion according to ASCII values
for (var i = 0; i < ln; i++)
{
if (str[i] >= 'a' && str[i] <= 'z')
// Convert lowercase to uppercase
document.write(
String.fromCharCode(str.charCodeAt(i) - 32)
);
else if (str[i] >= 'A' && str[i] <= 'Z')
// Convert uppercase to lowercase
document.write(
String.fromCharCode(str.charCodeAt(i) + 32)
);
}
}
// Driver function
var str = "GeEkSfOrGeEkS";
// Calling the Function
convertOpposite(str);
</script>
<?php
// Function to convert characters
// of a string to opposite case
function convertOpposite($str)
{
$ln = strlen($str);
// Conversion according to ASCII values
for ($i = 0; $i < $ln; $i++)
{
if ($str[$i] >= '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
?>
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:
- Print the string after all operations
Below is the implementation of the above approach:
C++
// C++ program to toggle all characters
#include <bits/stdc++.h>
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$";
toggleChars(S);
cout << "String after toggle " << endl;
cout << S << endl;
return 0;
}
// Code contributed by koulick_sadhu
// C program to toggle all characters
#include <ctype.h>
#include <stdio.h>
// Function to toggle characters
void toggleChars(char* S)
{
while (*S) {
if (isalpha(*S)) {
*S ^= (1 << 5);
}
++S;
}
}
// Driver code
int main()
{
char S[] = "GeKf@rGeek$";
toggleChars(S);
printf("String after toggle:\n%s\n", S);
return 0;
}
// Java program to toggle all characters
import java.util.*;
class GFG {
static char[] S = "GeKf@rGeek$".toCharArray();
// Function to toggle characters
static void toggleChars()
{
for (int i = 0; i < S.length; i++) {
if (Character.isAlphabetic(S[i])) {
S[i] ^= (1 << 5);
}
}
}
// Driver code
public static void main(String[] args)
{
toggleChars();
System.out.print("String after toggle "
+ "\n");
System.out.print(String.valueOf(S));
}
}
// This code is contributed by Amit Katiyar
# python program for the same approach
def isalpha(input):
input_char = ord(input[0])
# CHECKING FOR ALPHABET
if((input_char >= 65 and input_char <= 90) or (input_char >= 97 and input_char <= 122)):
return True
else:
return False
# Function to toggle characters
def toggleChars(S):
s = ""
for it in range(len(S)):
if(isalpha(S[it])):
s += chr(ord(S[it]) ^ (1 << 5))
else:
s += S[it]
return s
# Driver code
S = "GeKf@rGeek$"
print(f"String after toggle {toggleChars(S)}")
# This code is contributed by shinjanpatra
// C# program to toggle all characters
using System;
class GFG {
static char[] S = "GeKf@rGeek$".ToCharArray();
// Function to toggle characters
static void toggleChars()
{
for (int i = 0; i < S.Length; i++) {
if (char.IsLetter(S[i])) {
S[i] = (char)((int)(S[i]) ^ (1 << 5));
}
}
}
// Driver code
public static void Main(String[] args)
{
toggleChars();
Console.Write("String after toggle "
+ "\n");
Console.Write(String.Join("", S));
}
}
// This code is contributed by Princi Singh
<script>
function isalpha(input)
{
var input_char = input.charCodeAt(0);
// CHECKING FOR ALPHABET
if (
(input_char >= 65 && input_char <= 90) ||
(input_char >= 97 && input_char <= 122))
{
return true;
}
else
{
return false;
}
}
// Function to toggle characters
function toggleChars(S)
{
var s = "";
for(var it = 0; it < S.length; it++)
{
if(isalpha(S.charAt(it)))
{
s += String.fromCharCode(S.charCodeAt(it)^(1<<5))
}
else{
s += S.charAt(it);
}
}
return s;
}
// Driver code
var S = "GeKf@rGeek$";
document.write( "String after toggle " +toggleChars(S));
</script>
// This code is contributed by Akshit Saxena
OutputString after toggle
gEkF@RgEEK$
Time Complexity: O(n)
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 <iostream>
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.
// C program to Convert characters
// of a string to opposite case
#include <ctype.h>
#include <stdio.h>
#include <string.h>
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;
}
// 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 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# 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 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.
Approach : Using index() method
C++
// C++ program to Convert characters
// of a string to opposite case
#include <iostream>
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
// C program to Convert characters
// of a string to opposite case
#include <stdio.h>
#include <string.h>
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;
}
// 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 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# 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 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.
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 <bits/stdc++.h>
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
// C program to Convert characters
// of a string to opposite case
#include <ctype.h>
#include <stdio.h>
#include <string.h>
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;
}
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);
}
}
# 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# 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);
}
}
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
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 <ctype.h>
#include <stdio.h>
#include <string.h>
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;
}
import java.io.*;
public class GFG {
public static void main(String[] args) {
String str = "GeEkSfOrGeEkS";
char[] charArray = str.toCharArray();
// Convert the string to a character array
for (int i = 0; i < charArray.length; i++) {
if (Character.isUpperCase(charArray[i])) {
charArray[i] = Character.toLowerCase(charArray[i]);
// Convert uppercase to lowercase
} else {
charArray[i] = Character.toUpperCase(charArray[i]);
// Convert lowercase to uppercase
}
}
String toggledStr = new String(charArray);
// Convert the character array back to string
System.out.println(toggledStr);
}
}
str_value = "GeEkSfOrGeEkS"
p = 0 # Initialize an index variable to start of string
str_list = list(str_value) # Convert the string to a list of characters
while p < len(str_list):
if str_list[p].isupper():
str_list[p] = str_list[p].lower()
else:
str_list[p] = str_list[p].upper()
p += 1 # Move index to the next character
result = ''.join(str_list) # Convert the list back to a string
print(result)
# This code is contributed by akshitaguprzj3
using System;
class Program {
static void Main(string[] args)
{
string str = "GeEkSfOrGeEkS";
char[] charArray
= str.ToCharArray(); // Convert the string to a
// character array
for (int i = 0; i < charArray.Length; i++) {
if (char.IsUpper(
charArray[i])) // Check if the character
// is uppercase
{
charArray[i] = char.ToLower(
charArray[i]); // Convert to lowercase
}
else {
charArray[i] = char.ToUpper(
charArray[i]); // Convert to uppercase
}
}
string modifiedStr = new string(
charArray); // Convert the character array back
// to a string
Console.WriteLine(modifiedStr);
}
}
// JavaScript Program for the above approach
const str = "GeEkSfOrGeEkS";
let result = "";
for (let i = 0; i < str.length; i++) {
const char = str.charAt(i);
if (char === char.toUpperCase()) {
result += char.toLowerCase();
} else {
result += char.toUpperCase();
}
}
console.log(result);
// THIS CODE IS CONTRIBUTED BY PIYUSH AGARWAL
Time Complexity:- O(n) Where N is length of input String
Auxiliary Space:- O(1)
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Lower case to upper case - An interesting fact Problem: Given a string containing only lowercase letters, generate a string with the same letters, but in uppercase. Input : GeeksForGeeks Output : GEEKSFORGEEKS Recommended PracticeLower case to upper caseTry It! The first method that comes to our mind is C++ // C++ program to convert a string to
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Toggle case of a string using Bitwise Operators Given a string, write a function that returns toggle case of a string using the bitwise operators in place.In ASCII codes, character ‘A’ is integer 65 = (0100 0001)2, while character ‘a’ is integer 97 = (0110 0001)2. Similarly, character 'D' is integer 68 = (0100 0100)2, while character 'd' is integ
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