Table of Contents📚

• What is a string❔
• len method
• is_empty method
• split_whitespace method
• contains method
• push_str method

Strings📝

What is a string❔

In programming, a string is a sequence of characters.

In rust, there are two datatypes types for strings: str and String.

str is the primitive type that represents a string, String is more powerful.

In this section, we will be referring to the type String.

len method

The len method is used to get the length of a string, it returns an usize value.

let name = String::from("Léopold");

println!("My name has {} characters", name.len());

Output:

My name has 8 characters

is_empty method

The is_empty method is used to check if a string is empty, it returns a bool value.

let name = String::from("Léopold");
let empty = String::from("");

if name.is_empty() { // check if name is an empty string
    println!("'{}' is empty", name);
} else {
    println!("'{}' is not empty", name);
}

if empty.is_empty() { // check if empty is an empty string
    println!("'{}' is empty", empty);
} else {
    println!("'{}' is not empty", empty);
}

Output:

'Léopold' is not empty
'' is empty

split_whitespace method

The split_whitespace method is used to split a string into substrings, it returns an iterator so we can iterate over the substrings.

let text = String::from("Hello world");

for word in text.split_whitespace() {
    println!("Word : {}", word);
}

Output:

Word : Hello
Word : world

contains method

The contains method is used to check if a string contains a substring, it returns a bool value.

let text = String::from("Hello world");

if text.contains("world") {
    println!("'{}' contains 'world' ✅", text);
} else {
    println!("'{}' does not contain 'world' ⛔", text);
}

Output:

'Hello world' contains 'world' ✅

push_str method

The push_str method is used to happend text to a string, the string needs to be mutable because we are changing it.

let mut text = String::from("Hello"); 

println!("{}", text); 

text.push_str(" world"); 

println!("{}", text);

Output:

Hello
Hello world

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