/*
get_country_name
Receives a 2‑letter ISO country code and returns the
corresponding country name.
Uses a HashMap for O(1) lookups.
Input is normalized to uppercase to ensure consistent matching.
Returns None if the code is not found.
*/
fn get_country_name(alpha2: &str) -> Option<&'static str> {
// Static lookup table; extend as needed
static COUNTRY_MAP: phf::Map<&'static str, &'static str> = phf::phf_map! {
"CA" => "Canada",
"CN" => "China",
"DE" => "Germany",
"FR" => "France",
"GB" => "United Kingdom",
"KR" => "South Korea",
"IN" => "India",
"JP" => "Japan",
"US" => "United States",
};
// Normalize input
let code = alpha2.trim().to_uppercase();
// Lookup
COUNTRY_MAP.get(code.as_str()).copied()
}
/*
main
Demonstrates the lookup function with several sample codes.
*/
fn main() {
let codes = ["US", "GB", "FR", "JP", "ZZ"]; // ZZ is intentionally invalid
for code in &codes {
match get_country_name(code) {
Some(name) => println!("{code} → {name}"),
None => println!("{code} → (invalid code)"),
}
}
}
/*
run:
US → United States
GB → United Kingdom
FR → France
JP → Japan
ZZ → (invalid code)
*/
