# IndexOf()

*noun*

say it: **“IN-deks-uv”** **/ˈɪndɛksəv/**

A string method that returns the position where a character or piece of text is found, or -1 if it is not there.

## What is **IndexOf()** in C#?

**IndexOf()** — A string method that finds a character or piece of text and returns its position, counting from 0. It returns `-1` when the text isn't there, so check for that before you use the result.

```csharp
string email = "jordan@books.com";
Console.WriteLine(email.IndexOf('@'));    // 6
Console.WriteLine(email.IndexOf("shop")); // -1
```

## In a sentence

- “I used **IndexOf** to find the @ in the email address.”

Level: Apprentice · [More C# terms at this level](https://www.ask-codey.com/glossary?category=c-sharp&level=2)

Updated: October 28, 2026

Source: https://www.ask-codey.com/glossary/indexof