Lower case to upper case – An interesting fact
Last Updated :
24 Mar, 2023
Problem: Given a string containing only lowercase letters, generate a string with the same letters, but in uppercase.
Input : GeeksForGeeks
Output : GEEKSFORGEEKS
The first method that comes to our mind is
C++
#include <iostream>
using namespace std;
string to_upper(string &in)
{
for (int i = 0; i < in.length(); i++)
if ('a' <= in[i] <= 'z')
in[i] = in[i] - 'a' + 'A';
return in;
}
int main()
{
string str = "geeksforgeeks";
cout << to_upper(str);
return 0;
}
|
Java
class GFG
{
static String to_upper(char[] in)
{
for (int i = 0; i < in.length; i++)
{
if ('a' <= in[i] & in[i] <= 'z')
{
in[i] = (char) (in[i] - 'a' + 'A');
}
}
return String.valueOf(in);
}
public static void main(String[] args)
{
String str = "geeksforgeeks";
System.out.println(to_upper(str.toCharArray()));
}
}
|
Python3
def to_upper(string):
for i in range(len(string)):
if ('a' <= string[i] <= 'z'):
string = (string[0:i] + chr(ord(string[i]) -
ord('a') + ord('A')) +
string[i + 1:])
return string;
if __name__ == '__main__':
str = "geeksforgeeks";
print(to_upper(str));
|
C#
using System;
class GFG
{
static String to_upper(char []In)
{
for (int i = 0; i < In.Length; i++)
{
if ('a' <= In[i] & In[i] <= 'z')
{
In[i] = (char) (In[i] - 'a' + 'A');
}
}
return String.Join("", In);
}
public static void Main()
{
String str = "geeksforgeeks";
Console.WriteLine(to_upper(str.ToCharArray()));
}
}
|
Javascript
<script>
function to_upper(input)
{
var result = new Array(input.length);
for (var i = 0; i < input.length; i++)
if ("a".charCodeAt(0) <= input[i].charCodeAt(0) <= "z".charCodeAt(0))
result[i] = String.fromCharCode(
input[i].charCodeAt(0) - "a".charCodeAt(0) + "A".charCodeAt(0)
);
return result.join("").toString();
}
var str = "geeksforgeeks";
document.write(to_upper(str));
</script>
|
Time Complexity: O(n),where n is length of string.
Auxiliary Space: O(1)
A more interesting solution, on the other hand, would be:
C++
#include <iostream>
using namespace std;
string to_upper(string &in)
{
for (int i = 0; i < in.length(); i++)
if ('a' <= in[i] <= 'z')
in[i] &= ~(1 << 5);
return in;
}
int main()
{
string str = "geeksforgeeks";
cout << to_upper(str);
return 0;
}
|
Java
class GFG
{
static String to_upper(char[] in)
{
for (int i = 0; i < in.length; i++)
if ('a' <= in[i] && in[i] <= 'z')
in[i] &= ~(1 << 5);
return String.valueOf(in);
}
public static void main(String[] args)
{
String str = "geeksforgeeks";
System.out.println(to_upper(str.toCharArray()));
}
}
|
Python3
def to_upper(s):
for i in range(len(s)):
if ('a' <= s[i] <= 'z'):
s = s[0:i] + chr(ord(s[i]) & \
(~(1 << 5))) + s[i + 1:];
return s;
if __name__ == '__main__':
string = "geeksforgeeks";
print(to_upper(string));
|
C#
using System;
class GFG
{
static String to_upper(char[] str)
{
for (int i = 0; i < str.Length; i++)
if ('a' <= str[i] && str[i] <= 'z')
str[i] = (char)((int)str[i]&(~(1 << 5)));
return String.Join("", str);
}
public static void Main(String[] args)
{
String str = "geeksforgeeks";
Console.WriteLine(to_upper(str.ToCharArray()));
}
}
|
Javascript
<script>
function to_upper(In)
{
let n = In.length;
for(let i = 0; i < In.length; i++)
if ('a' <= In[i] && In[i] <= 'z')
In[i] = String.fromCharCode(
In[i].charCodeAt(0) & (~(1 << 5)));
return (In).join("");
}
let str = "geeksforgeeks";
document.write(to_upper(str.split("")));
</script>
|
Time Complexity: O(n),where n is length of string.
Auxiliary Space: O(1)
Method 3(using C++ STL)
In C++ STL there is a function called “transform” which converts the case of all latter of a string.
Below is an implementation of that function:
C++
#include<bits/stdc++.h>
using namespace std;
void transform_to_upper(string &s){
transform(s.begin(),s.end(),s.begin(),::toupper);
cout<<"string with uppercase latter is: "<<endl;
cout<<s;
}
int main() {
string s="GeeksForGeeks";
transform_to_upper(s);
return 0;
}
|
Java
import java.util.*;
public class Main {
public static void transformToUpper(StringBuilder s)
{
s = new StringBuilder(s.toString().toUpperCase());
System.out.println("String with uppercase letters is:");
System.out.println(s);
}
public static void main(String[] args) {
StringBuilder s = new StringBuilder("GeeksForGeeks");
transformToUpper(s);
}
}
|
Python3
def transform_to_upper(s):
s = s.upper()
print("String with uppercase letters is: ")
print(s)
if __name__ == '__main__':
s = "GeeksForGeeks"
transform_to_upper(s)
|
C#
using System;
using System.Text;
public class MainClass {
public static void TransformToUpper(StringBuilder s)
{
s = new StringBuilder(s.ToString().ToUpper());
Console.WriteLine("String with uppercase letters is:");
Console.WriteLine(s);
}
public static void Main(string[] args) {
StringBuilder s = new StringBuilder("GeeksForGeeks");
TransformToUpper(s);
}
}
|
Javascript
function transformToUpperCase(s) {
s = s.toUpperCase();
console.log("String with uppercase letters is: ");
console.log(s);
}
const s = "GeeksForGeeks";
transformToUpperCase(s);
|
Output
string with uppercase latter is:
GEEKSFORGEEKS
Time Complexity: O(n),where n is length of string.
Auxiliary Space: O(1)
Explanation: The ASCII table is constructed in such way that the binary representation of lowercase letters is almost identical of binary representation of uppercase letters. The only difference is the sixth bit, setted only for lowercase letters. What that elegant function does is unset the bit of index 5 of in[i], consequently, making that character lowercase.
Disadvantages: That strategy works only for alphabetical characters. If the input contains numbers or punctuations, we’ll have to use the naive way.
Example: Character ‘A’ is integer 65 = (0100 0001)2, while character ‘a’ is integer = 97 = (0110 0001)2. (Note that 97 – 65 = 32. Can you guess why?)
Exercises:
- Write a function to make all letters of a string lowercase. Example: GeeksForGeeks turns geeksforgeeks.
- Write a function that change the case of a string. Example: GeeksForGeeks turns gEEKSfORgEEKS.
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