how-do-i-find-the-index-of-a-substring-in-a-string-in-rust?.md

How do I find the index of a substring in a string in Rust?

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The find() method of the str type can be used to find the index of a substring in a string in Rust.

Example code

let s = "Hello World!";
let index = s.find("World");

Output example

Some(6)

The find() method takes a &str as an argument and returns an Option<usize> which is Some(index) if the substring is found, or None if it is not found.

Code explanation

• let s = "Hello World!";: This declares a string variable s with the value Hello World!.
• let index = s.find("World");: This calls the find() method on the s string variable, passing in the substring World as an argument.
• Some(6): This is the output of the find() method, which is Some(index) if the substring is found, or None if it is not found. In this case, the substring World is found at index 6.

Helpful links

• Rust Documentation - Strings