Question

If a string has 10 characters, what is the index of the last character?

Short answer

Answer: The index of the last character in a string with 10 characters is 9.

Step-by-step solution

Understand the indexing system

In most programming languages, the indexing of a string starts at 0. That means the first character has an index of 0, the second has an index of 1, and so on.

Subtract 1 from the total number of characters

We are given that the string has 10 characters, which means the last character is the 10th character. Since indexing starts at 0, we need to subtract 1 from the total number of characters (10) to find the index of the last character. Mathematically, this is represented as: Index of last character = Total characters - 1

Calculate the index

Now, we just need to plug in the values to find the index of the last character: Index of last character = 10 - 1 = 9 So, the index of the last character in the string is 9.

Key concepts

Zero-Based Indexing

Understanding zero-based indexing is essential to getting a good grasp on how strings are handled in programming. Imagine a string as a lineup of characters, each having a designated spot in the sequence. These spots are what we refer to as 'indexes'.

In zero-based indexing, the count starts from zero, not one. This means that the first character in the string is at index 0, the next is at index 1, and so forth. Think of it as how floors in a building are often numbered starting from 0 in some countries, often called the 'ground floor'.

• The first character's position is 0.
• The second character's position is 1.
• Continue this pattern, and you reach the last character.

So, in a 10-character string, counting starts from 0 and goes up to 9, making the index of the last character 9. It's a common mistake to presume the last index is the total character count, but remembering that zero-based index means 'start at 0' will help clarify this point.

Programming Fundamentals

String indexing is a fundamental concept in programming, as it allows you to access individual characters in a string. Imagine you're dealing with a series of mailboxes lined up in a row, each containing a piece of a message. Indexing helps you locate each piece of the message precisely.

Learning to navigate strings using their indexes enables you to:

• Extract specific characters.
• Perform searches within strings.
• Replace or modify characters.

It's a stepping stone to more complex operations like loops and conditional statements. For a 10-character string, remember the mailbox analogy—the 10th mailbox would be indexed as 9, in line with zero-based indexing.

String Manipulation

String manipulation is where the concepts of indexing turn into practical skills. It's the art of changing, splitting, joining, or analyzing strings based on different requirements.

Consider a scenario where you want to personalize a greeting in a program by using the user's name, which is stored as a string. Here's where string manipulation comes into play:

• To to get the last letter of the user's name, you would use its index in the string.
• If the name has 10 characters, you'd use index 9, not 10, to find the last character.
• Understanding the zero-based index system directly affects your ability to manipulate strings effectively.

With these skills, creating dynamic and interactive content in your software becomes a much more straightforward task.