Best Rust Programming Books to Buy in October 2025
The Rust Programming Language, 2nd Edition
Programming Rust: Fast, Safe Systems Development
Rust for Rustaceans: Idiomatic Programming for Experienced Developers
Rust in Action
Rust Programming: A Practical Guide to Fast, Efficient, and Safe Code with Ownership, Concurrency, and Web Programming (Rheinwerk Computing)
Zero To Production In Rust: An introduction to backend development
The Rust Programming Language
Rust Atomics and Locks: Low-Level Concurrency in Practice
Asynchronous Programming in Rust: Learn asynchronous programming by building working examples of futures, green threads, and runtimes
In Rust, you can check if a string only contains a specific set of characters by iterating through each character in the string and verifying if it belongs to the set of allowed characters. Here's an example of how you can do this:
fn only_contains_characters(input: &str, allowed_chars: &str) -> bool { for c in input.chars() { if !allowed_chars.contains(c) { return false; } } true }
In the above code, the function only_contains_characters takes two parameters: input which is the string you want to check, and allowed_chars which is a string containing the set of characters that are allowed.
The function iterates through each character in the input string using the chars method. For each character, it checks if it exists within the allowed_chars string using the contains method. If a character is not found in the allowed_chars string, the function immediately returns false, indicating that the string does not contain only the allowed characters. Otherwise, if all characters pass the check, the function returns true, indicating that the string only contains the allowed characters.
You can use this function in your code to check if a string only contains a specific set of characters. For example:
fn main() { let input = "hello123"; let allowed_chars = "abcdefghijklmnopqrstuvwxyz";
if only\_contains\_characters(input, allowed\_chars) {
println!("The string contains only allowed characters.");
} else {
println!("The string contains invalid characters.");
}
}
In the above example, the input variable contains the string you want to check, and the allowed_chars variable contains the set of characters that are allowed (in this case, the lowercase alphabet). The main function calls the only_contains_characters function and prints an appropriate message depending on the result.
How to check if a string only contains characters from a specific language set in Rust?
To check if a string only contains characters from a specific language set in Rust, you can use regular expressions combined with the regex crate.
Here's an example that checks if a string contains only uppercase Latin letters:
- Add regex as a dependency in your Cargo.toml file:
[dependencies] regex = "1.3.0"
- Use the crate by adding the following line in your Rust code:
use regex::Regex;
- Write a function to check if the string contains only characters from the desired language set:
fn contains_only_language_set(text: &str, language_set_regex: &str) -> bool { let regex = Regex::new(&format!("^{}*$", language_set_regex)).unwrap(); regex.is_match(text) }
In the function, the ^ character denotes the start of the string, * denotes zero or more occurrences, and $ denotes the end of the string. The language_set_regex argument is a regular expression that defines the desired language set.
- Call the function with the input string and the regular expression representing the desired character set:
fn main() { let text = "ABC"; let language_set_regex = r"^[A-Z]*$"; let is_only_language_set = contains_only_language_set(text, language_set_regex); println!("Is only in language set: {}", is_only_language_set); }
In this example, the regular expression ^[A-Z]*$ ensures that the string contains only uppercase Latin letters.
You can adjust the regular expression (language_set_regex) accordingly to match different language sets.
How to check if a string only contains a specific character in Rust?
You can use the chars() function to iterate over the characters of the string and check if all of them are the specific character you are looking for. Here's an example code:
fn contains_only_char(s: &str, c: char) -> bool { for ch in s.chars() { if ch != c { return false; } } true }
fn main() { let s1 = "cccccccccc"; let s2 = "cccccccccd"; let c = 'c';
if contains\_only\_char(s1, c) {
println!("String {} contains only character '{}'", s1, c);
} else {
println!("String {} does not contain only character '{}'", s1, c);
}
if contains\_only\_char(s2, c) {
println!("String {} contains only character '{}'", s2, c);
} else {
println!("String {} does not contain only character '{}'", s2, c);
}
}
Output:
String cccccccccc contains only character 'c' String ccccccccd does not contain only character 'c'
In this code, the contains_only_char function takes a string s and a character c, and it checks if all characters in s are equal to c. If any character is not equal to c, the function returns false. Otherwise, if all characters are equal to c, it returns true.
How to count the number of whitespace characters in a string using Rust?
There are multiple ways to count the number of whitespace characters in a string using Rust. Here are two common approaches:
- Using the chars iterator and is_whitespace:
fn count_whitespace_chars(input: &str) -> usize { input.chars().filter(|&c| c.is_whitespace()).count() }
fn main() { let s = "This is a test string"; let whitespace_count = count_whitespace_chars(s); println!("Number of whitespace characters: {}", whitespace_count); }
- Using a regular expression to match whitespace characters:
use regex::Regex;
fn count_whitespace_chars(input: &str) -> usize { let re = Regex::new(r"\s").unwrap(); re.find_iter(input).count() }
fn main() { let s = "This is a test string"; let whitespace_count = count_whitespace_chars(s); println!("Number of whitespace characters: {}", whitespace_count); }
To use the second approach, you need to add the regex crate to your Cargo.toml file by adding the following line under the [dependencies] section:
regex = "1.4"
Remember to run cargo build or cargo run to download and build the crate.
How to use regular expressions to check if a string only contains alphanumeric characters in Rust?
In Rust, you can utilize the regex crate to check if a string only contains alphanumeric characters using regular expressions. Below is an example code snippet to demonstrate this:
First, add the regex crate to your Cargo.toml file:
[dependencies] regex = "1.5"
Then, in your Rust code:
use regex::Regex;
fn main() { let alphanumeric_regex = Regex::new(r"^[[:alnum:]]+$").unwrap();
let string1 = "Hello123";
let string2 = "Hello@123";
if alphanumeric\_regex.is\_match(string1) {
println!("String 1 contains only alphanumeric characters");
} else {
println!("String 1 contains non-alphanumeric characters");
}
if alphanumeric\_regex.is\_match(string2) {
println!("String 2 contains only alphanumeric characters");
} else {
println!("String 2 contains non-alphanumeric characters");
}
}
In this code, we create a Regex object named alphanumeric_regex using the regular expression ^[[:alnum:]]+$. This regular expression ensures that the string starts with one or more alphanumeric characters ([[:alnum:]]) and ends there ($ sign). The ^ and $ symbols represent the start and end of the input string, respectively.
We then check if string1 and string2 contain only alphanumeric characters by using the is_match function of the Regex object. Finally, we print the appropriate message based on whether the string contains only alphanumeric characters or not.
When you run this code, it will output:
String 1 contains only alphanumeric characters String 2 contains non-alphanumeric characters
You can modify the regular expression or the input strings as needed for your specific use case.
How to detect and retrieve non-alphanumeric characters from a string in Rust?
To detect and retrieve non-alphanumeric characters from a string in Rust, you can use regular expressions. Here's an example code that demonstrates this:
use regex::Regex;
fn get_non_alphanumeric_chars(input: &str) -> Vec { let re = Regex::new(r"[^0-9a-zA-Z]").unwrap(); let non_alphanumeric_chars: Vec = re.find_iter(input) .flat_map(|m| input[m.start()].to_lowercase()) // Convert to lowercase if necessary .collect();
non\_alphanumeric\_chars
}
fn main() { let input = "Hello! My name is 123."; let non_alphanumeric_chars = get_non_alphanumeric_chars(input); println!("Non-alphanumeric chars: {:?}", non_alphanumeric_chars); }
In this code, we use the regex crate to create a regular expression pattern [^0-9a-zA-Z] which matches any character that is not a digit or an alphabet. We then create a Regex instance with this pattern.
The find_iter method of the Regex instance returns an iterator over non-overlapping matches in the input string. We use flat_map to iterate over the matches, and collect the non-alphanumeric characters into a vector of characters.
Finally, we print the non-alphanumeric characters from the input string. In this case, the output would be [ '!', ' ' , ' ', ' ', '.' ].
Make sure to add regex as a dependency in your Cargo.toml file:
[dependencies] regex = "1.4"
This code provides a basic implementation, you can modify and enhance it based on your specific requirements.
What is the best way to validate if a string only contains lowercase letters in Rust?
In Rust, you can use the is_lowercase method of the char type to validate if a string only contains lowercase letters. Here's an example:
fn contains_only_lowercase_letters(string: &str) -> bool { string.chars().all(|c| c.is_lowercase()) }
fn main() { let string1 = "hello"; let string2 = "Hello";
println!("String1: {}", contains\_only\_lowercase\_letters(string1));
println!("String2: {}", contains\_only\_lowercase\_letters(string2));
}
The contains_only_lowercase_letters function takes a string as input and loops over each character in the string using the chars method. For each character, it uses the is_lowercase method to check if it is a lowercase letter. The all method is used to ensure that all characters in the string satisfy the condition c.is_lowercase(). If any character fails this condition, the function returns false, indicating that the string contains non-lowercase characters. Otherwise, it returns true, indicating that the string contains only lowercase letters.
In the example, the output will be:
String1: true String2: false
Since the string "hello" only contains lowercase letters, contains_only_lowercase_letters returns true. On the other hand, the string "Hello" contains an uppercase letter, so the function returns false.