Print first letter of each word in a string using regex

Given a string, extract the first letter of each word in it. “Words” are defined as contiguous strings of alphabetic characters i.e. any upper or lower case characters a-z or A-Z.

Examples:

Input : Geeks for geeks
Output :Gfg
        
Input : United Kingdom
Output : UK

Below is the Regular expression to extract the first letter of each word. It uses ‘/b'(one of boundary matchers). Please refer How to write Regular Expressions? to learn it.

\b[a-zA-Z]

// Java program to demonstrate extracting first
// letter of each word using Regex

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Test
{
    public static void main(String[] args)
    {
        String s1 = "Geeks for Geeks";
        String s2 = "A Computer Science Portal for Geeks";

        Pattern p = Pattern.compile("\\b[a-zA-Z]");

        Matcher m1 = p.matcher(s1);
        Matcher m2 = p.matcher(s2);

        System.out.println("First letter of each word from string \"" + s1 + "\" : ");
        while (m1.find())
            System.out.print(m1.group());

        System.out.println();

        System.out.println("First letter of each word from string \"" + s2 + "\" : ");

        while (m2.find())
            System.out.print(m2.group());


    }
}

Output:

First letter of each word from string "Geeks for Geeks" : 
GfG
First letter of each word from string "A Computer Science Portal for Geeks" : 
ACSPfG

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