String containing first letter of every word in a given string with spaces
Last Updated :
23 Jul, 2025
String str is given which contains lowercase English letters and spaces. It may contain multiple spaces. Get the first letter of every word and return the result as a string. The result should not contain any space.
Examples:
Input : str = "geeks for geeks"
Output : gfg
Input : str = "geeks for geeks""
Output : hc
Source: https://www.geeksforgeeks.org/interview-experiences/amazon-interview-set-8-2/
The idea is to traverse each character of string str and maintain a boolean variable, which was initially set as true. Whenever we encounter space we set the boolean variable is true. And if we encounter any character other than space, we will check the boolean variable, if it was set as true as copy that charter to the output string and set the boolean variable as false. If the boolean variable is set false, do nothing.
Algorithm:
1. Traverse string str. And initialize a variable v as true.
2. If str[i] == ' '. Set v as true.
3. If str[i] != ' '. Check if v is true or not.
a) If true, copy str[i] to output string and set v as false.
b) If false, do nothing.
Implementation:
C++
// C++ program to find the string which contain
// the first character of each word of another
// string.
#include<bits/stdc++.h>
using namespace std;
// Function to find string which has first
// character of each word.
string firstLetterWord(string str)
{
string result = "";
// Traverse the string.
bool v = true;
for (int i=0; i<str.length(); i++)
{
// If it is space, set v as true.
if (str[i] == ' ')
v = true;
// Else check if v is true or not.
// If true, copy character in output
// string and set v as false.
else if (str[i] != ' ' && v == true)
{
result.push_back(str[i]);
v = false;
}
}
return result;
}
// Driver code
int main()
{
string str = "geeks for geeks";
cout << firstLetterWord(str);
return 0;
}
// Java program to find the string which
// contain the first character of each word
// of another string.
class GFG
{
// Function to find string which has first
// character of each word.
static String firstLetterWord(String str)
{
String result = "";
// Traverse the string.
boolean v = true;
for (int i = 0; i < str.length(); i++)
{
// If it is space, set v as true.
if (str.charAt(i) == ' ')
{
v = true;
}
// Else check if v is true or not.
// If true, copy character in output
// string and set v as false.
else if (str.charAt(i) != ' ' && v == true)
{
result += (str.charAt(i));
v = false;
}
}
return result;
}
// Driver code
public static void main(String[] args)
{
String str = "geeks for geeks";
System.out.println(firstLetterWord(str));
}
}
// This code is contributed by
// 29AjayKumar
# Python 3 program to find the string which
# contain the first character of each word
# of another string.
# Function to find string which has first
# character of each word.
def firstLetterWord(str):
result = ""
# Traverse the string.
v = True
for i in range(len(str)):
# If it is space, set v as true.
if (str[i] == ' '):
v = True
# Else check if v is true or not.
# If true, copy character in output
# string and set v as false.
elif (str[i] != ' ' and v == True):
result += (str[i])
v = False
return result
# Driver Code
if __name__ == "__main__":
str = "geeks for geeks"
print(firstLetterWord(str))
# This code is contributed by ita_c
// C# program to find the string which
// contain the first character of each word
// of another string.
using System;
class GFG
{
// Function to find string which has first
// character of each word.
static String firstLetterWord(String str)
{
String result = "";
// Traverse the string.
bool v = true;
for (int i = 0; i < str.Length; i++)
{
// If it is space, set v as true.
if (str[i] == ' ')
{
v = true;
}
// Else check if v is true or not.
// If true, copy character in output
// string and set v as false.
else if (str[i] != ' ' && v == true)
{
result += (str[i]);
v = false;
}
}
return result;
}
// Driver code
public static void Main()
{
String str = "geeks for geeks";
Console.WriteLine(firstLetterWord(str));
}
}
// This code is contributed by PrinciRaj1992
<script>
// Javascript program to find the string which
// contain the first character of each word
// of another string.
// Function to find string which has first
// character of each word.
function firstLetterWord(str)
{
let result = "";
// Traverse the string.
let v = true;
for (let i = 0; i < str.length; i++)
{
// If it is space, set v as true.
if (str[i] == ' ')
{
v = true;
}
// Else check if v is true or not.
// If true, copy character in output
// string and set v as false.
else if (str[i] != ' ' && v == true)
{
result += (str[i]);
v = false;
}
}
return result;
}
let str = "geeks for geeks";
document.write(firstLetterWord(str));
</script>
Time Complexity: O(n)
Auxiliary space: O(1).
Approach 1 : Reverse Iterative Approach
This is simplest approach to getting first letter of every word of the string. In this approach we are using reverse iterative loop to get letter of words. If particular letter ( i ) is 1st letter of word or not is can be determined by checking pervious character that is (i-1). If the pervious letter is space (' ') that means (i+1) is 1st letter then we simply add that letter to the string. Except character at 0th position. At the end we simply reverse the string and function will return string which contain 1st letter of word of the string.
C++
#include <iostream>
using namespace std;
void get(string s)
{
string str = "", temp = "";
for (int i = s.length() - 1; i > 0; i--) {
if (isalpha(s[i]) && s[i - 1] == ' ') {
temp += s[i];
}
}
str += s[0];
for (int i = temp.length() - 1; i >= 0; i--) {
str += temp[i];
}
cout << str << endl;
}
int main()
{
string str = "geeks for geeks";
string str2 = "Code of the Day";
get(str);
get(str2);
return 0;
}
// This code is contributed by sarojmcy2e
public class GFG {
public static void get(String s)
{
String str = "", temp = "";
// checking condition
for (int i = s.length() - 1; i > 0; i--) {
if (Character.isLetter(s.charAt(i))
&& s.charAt(i - 1) == ' ') {
temp
+= s.charAt(i); // if consition match
// added it to the string
}
}
// adding 1st letter of string
str += s.charAt(0);
// adding remaning letters
for (int i = temp.length() - 1; i >= 0; i--) {
str += temp.charAt(i);
}
System.out.println(str);
}
public static void main(String[] args)
{
String str = "geeks for geeks";
String str2 = "Code of the Day";
get(str); // function call
get(str2); // function call
}
}
def get(s):
str = ""
temp = ""
for i in range(len(s)-1, 0, -1):
if s[i].isalpha() and s[i-1] == ' ':
temp += s[i]
str += s[0]
for i in range(len(temp)-1, -1, -1):
str += temp[i]
print(str)
str = "geeks for geeks"
str2 = "Code of the Day"
get(str)
get(str2)
using System;
public class GFG {
public static void Get(string s)
{
string str = "", temp = "";
// checking condition
for (int i = s.Length - 1; i > 0; i--) {
if (char.IsLetter(s[i]) && s[i - 1] == ' ') {
temp += s[i]; // if consition match
// added it to the string
}
}
// adding 1st letter of string
str += s[0];
// adding remaning letters
for (int i = temp.Length - 1; i >= 0; i--) {
str += temp[i];
}
Console.WriteLine(str);
}
public static void Main(string[] args)
{
string str = "geeks for geeks";
string str2 = "Code of the Day";
Get(str); // function call
Get(str2); // function call
}
}
function get(s) {
let str = "", temp = "";
for (let i = s.length - 1; i > 0; i--) {
if (s[i].match(/[a-zA-Z]/) && s[i - 1] === ' ') {
temp += s[i];
}
}
str += s[0];
for (let i = temp.length - 1; i >= 0; i--) {
str += temp[i];
}
console.log(str);
}
const str = "geeks for geeks";
const str2 = "Code of the Day";
get(str);
get(str2);
Time Complexity: O(n)
Auxiliary space: O(1).
Approach 2: Using StringBuilder
This approach uses the StringBuilder class of Java. In this approach, we will first split the input string based on the spaces. The spaces in the strings can be matched using a regular expression. The split strings are stored in an array of strings. Then we can simply append the first character of each split string in the String Builder object.
Implementation:
C++
// C++ implementation of the above approach
#include <bits/stdc++.h>
using namespace std;
string processWords(char *input)
{
/* we are splitting the input based on
spaces (s)+ : this regular expression
will handle scenarios where we have words
separated by multiple spaces */
char *p;
vector<string> s;
p = strtok(input, " ");
while (p != NULL)
{
s.push_back(p);
p = strtok(NULL, " ");
}
string charBuffer;
for (string values : s)
/* charAt(0) will pick only the first character
from the string and append to buffer */
charBuffer += values[0];
return charBuffer;
}
// Driver code
int main()
{
char input[] = "geeks for geeks";
cout << processWords(input);
return 0;
}
// This code is contributed by
// sanjeev2552
// Java implementation of the above approach
class GFG
{
private static StringBuilder charBuffer = new StringBuilder();
public static String processWords(String input)
{
/* we are splitting the input based on
spaces (s)+ : this regular expression
will handle scenarios where we have words
separated by multiple spaces */
String s[] = input.split("(\\s)+");
for(String values : s)
{
/* charAt(0) will pick only the first character
from the string and append to buffer */
charBuffer.append(values.charAt(0));
}
return charBuffer.toString();
}
// main function
public static void main (String[] args)
{
String input = "geeks for geeks";
System.out.println(processWords(input));
}
}
// This code is contributed by Goutam Das
# An efficient Python3 implementation
# of above approach
charBuffer = []
def processWords(input):
""" we are splitting the input based on
spaces (s)+ : this regular expression
will handle scenarios where we have words
separated by multiple spaces """
s = input.split(" ")
for values in s:
""" charAt(0) will pick only the first
character from the string and append
to buffer """
charBuffer.append(values[0])
return charBuffer
# Driver Code
if __name__ == '__main__':
input = "geeks for geeks"
print(*processWords(input), sep = "")
# This code is contributed
# by SHUBHAMSINGH10
// C# implementation of above approach
using System;
using System.Text;
class GFG
{
private static StringBuilder charBuffer = new StringBuilder();
public static String processWords(String input)
{
/* we are splitting the input based on
spaces (s)+ : this regular expression
will handle scenarios where we have words
separated by multiple spaces */
String []s = input.Split(' ');
foreach(String values in s)
{
/* charAt(0) will pick only the first character
from the string and append to buffer */
charBuffer.Append(values[0]);
}
return charBuffer.ToString();
}
// Driver code
public static void Main()
{
String input = "geeks for geeks";
Console.WriteLine(processWords(input));
}
}
// This code is contributed by Rajput-Ji
<script>
// Javascript implementation of the above approach
var charBuffer = "";
function processWords(input)
{
/* we are splitting the input based on
spaces (s)+ : this regular expression
will handle scenarios where we have words
separated by multiple spaces */
var s = input.split(' ');
s.forEach(element => {
/* charAt(0) will pick only the first character
from the string and append to buffer */
charBuffer+=element[0];
});
return charBuffer;
}
// Driver code
var input = "geeks for geeks";
document.write( processWords(input));
// This code is contributed by rutvik_56.
</script>
Time Complexity: O(n)
Auxiliary space: O(1).
Another Approach: Using boundary checker, refer https://www.geeksforgeeks.org/java/get-first-letter-word-string-using-regex-java/
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