How to convert an ASCII character to uppercase in Rust
Overview
ASCII stands for American Standard Code for Information Interchange. It is a way of encoding a character set used for communication between computers. ASCII is the first among many encodings such as the UTF-8, ISO-8859-1, and so on.
A character is an ASCII character if it is a number between 0 and 9, an uppercase or lowercase letter from the English alphabet, or some special character. In Rust, we can use the is_ascii() method to check if a character is within the ASCII range.
Rust provides two methods to convert an ASCII lowercase character to uppercase: to_ascii_uppercase() and make_ascii_uppercase().
Note: These methods have no effect on characters that are ASCII numbers, ASCII special characters, and non-ASCII characters.
Syntax
The code snippet below demonstrates how to use the to_ascii_uppercase() method.
character.to_ascii_uppercase()
The following code snippet demonstrates how to use the make_ascii_uppercase() method.
character.make_ascii_uppercase()
Parameters
Both methods require one input parameter:
character: This is the character we want to convert to uppercase.
Return value
The to_ascii_uppercase() method returns the uppercase ASCII equivalent of the input character. The above code snippet for to_ascii_uppercase() will return the uppercase equivalent for character.
The make_ascii_uppercase() method converts the input character to its uppercase ASCII equivalent. The above code snippet for make_ascii_uppercase() will convert the character to its uppercase equivalent.
Example
Let’s look at a few examples that use the above two methods to convert characters to uppercase in Rust.
fn main(){
// Create characters
let char1 = 't';
let char2 = '❤';
let char3 = '!';
// use to_ascii_uppercase() to convert to uppercase
println!("{} uppercase is {}", char1, char1.to_ascii_uppercase());
println!("{} uppercase is {}", char2, char2.to_ascii_uppercase());
println!("{} uppercase is {}", char3, char3.to_ascii_uppercase());
// Create characters
let mut char4 = 'a';
let mut char5 = '❤';
let mut char6 = '!';
// use make_ascii_uppercase() to convert to uppercase
char4.make_ascii_uppercase();
char5.make_ascii_uppercase();
char6.make_ascii_uppercase();
// print uppercase characters
println!("{}", char4);
println!("{}", char5);
println!("{}", char6);
}Explanation
- Lines 1–3: We create three characters. Only the first character,
char1, is an ASCII letter character. - Lines 7–9: We use
to_ascii_uppercase()to convert the above three characters to uppercase and print the result. The output shows thatto_ascii_uppercaseonly returns a different value forchar1. - Lines 11–13: We create three more characters. Only
char4is an ASCII letter character. - Lines 15–17: We use
make_ascii_uppercase()to convert the new characters to uppercase. - Lines 19–21: We print
char4,char5, andchar6. The output shows thatmake_ascii_uppercaseonly changed the value ofchar4.
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