Register to get access to free programming courses with interactive exercises

Position within a string Regular Expressions (Regexp)

In this lesson, we will learn about special characters that can clarify the character's positions in strings and substrings.

Let us look at the following example:



Here, the word java matches the string java. It is a simple condition.

It is important to remember that regular expressions do not look for matches in strings but in substrings. If you search in a string containing characters besides the ones you look for, the check may show that the strings match, even though you did not want it:


asdfjava asdf

There are special characters to control character search in a string.

A character that represents the beginning of a line

If you put ^ in the search line before the characters you look for, only the characters at the beginning of strings will match:


java ruby clojurescript javascript

If we remove ^, we will have two matches, including one in the last substring:


java ruby clojurescript javascript

A character representing the end of a string

This character is $. Here is an example without this character. It has two matches:


java ruby clojurescript javascript

If we use $, we will have only one match at the end of the string:


java ruby clojurescript javascript

Searching for characters relative to their word boundaries

Suppose we only need to find instances of a at the end of a word. To do this, we type a\b in the string pattern:


java ruby clojurescript javascript

If we type \B, instead, we can invert the search and find all instances of a not at the end of a word:


java ruby clojurescript javascript

If you put \b in front of the character we search for, we will find the characters at the beginning of the word:


java ruby clojurescript javascript

Here we use inverting again:


java ruby clojurescriptj javascript

For clarity, if we compare it with the previous example, we added another j after the clojurescript in our string.

Now we find only instances of j that are neither at the beginning nor the end of a word:


java ruby clojurescriptj javascript

Hexlet Experts

Are there any more questions? Ask them in the Discussion section.

The Hexlet support team or other students will answer you.

About Hexlet learning process

For full access to the course you need a professional subscription.

A professional subscription will give you full access to all Hexlet courses, projects and lifetime access to the theory of lessons learned. You can cancel your subscription at any time.

Get access
hours of theory

Sign up

Programming courses for beginners and experienced developers. Start training for free

  • 130 courses, 2000+ hours of theory
  • 1000 practical tasks in a browser
  • 360 000 students
By sending this form, you agree to our Personal Policy and Service Conditions

Our graduates work in companies:

<span class="translation_missing" title="translation missing:">Bookmate</span>
<span class="translation_missing" title="translation missing:">Healthsamurai</span>
<span class="translation_missing" title="translation missing:">Dualboot</span>
<span class="translation_missing" title="translation missing:">Abbyy</span>
Suggested learning programs
Development of front-end components for web applications
10 months
from scratch
Start at any time

Use Hexlet to the fullest extent!

  • Ask questions about the lesson
  • Test your knowledge in quizzes
  • Practice in your browser
  • Track your progress

Sign up or sign in

By sending this form, you agree to our Personal Policy and Service Conditions
Toto Image

Ask questions if you want to discuss a theory or an exercise. Hexlet Support Team and experienced community members can help find answers and solve a problem.