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104 lines
2.6 KiB
104 lines
2.6 KiB
use std::env;
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use std::process;
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fn main() {
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let mut command = String::new();
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let mut command_args = Vec::<String>::new();
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for (i, arg) in env::args().enumerate() {
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match i {
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0 => continue,
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1 => {
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command = arg;
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continue;
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}
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_ => command_args.push(arg.clone()),
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}
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}
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match command.as_str() {
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"tc" => {
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if command_args.len() < 1 {
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eprintln!("ERROR: missing a value to convert");
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process::exit(1);
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}
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temp_convert(&command_args[0])
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}
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"fib" => {
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if command_args.len() < 1 {
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eprintln!("ERROR: missing a value to fib");
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process::exit(1);
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}
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let n: u64 = command_args[0]
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.parse()
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.expect("could not parse value to fib");
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if n >= 40 {
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eprintln!("WARN: this might take a while");
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}
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fib_n(n)
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}
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"rx" => redefine_x(),
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"help" => show_help(),
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_ => {
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show_help();
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eprintln!("ERROR: missing sub-command");
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process::exit(1);
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}
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}
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}
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fn show_help() {
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println!("Usage: variables <command> [command_args]");
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println!();
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println!("The value for <command> may be one of:");
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println!(" fib - generate Nth Fibonacci number");
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println!(" tc - convert temperatures between Fahrenheit and Celsius");
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println!(" rx - redefine x");
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println!();
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}
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fn redefine_x() {
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let mut x = 5;
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println!("The value of x is: {}", x);
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x = 6;
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println!("The value of x is: {}", x);
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}
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fn temp_convert(to_convert: &str) {
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let to_convert = to_convert.to_lowercase();
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if to_convert.ends_with("c") {
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let c: f32 = to_convert
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.trim_end_matches('c')
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.parse()
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.expect("failed to parse temperature");
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println!("{}F", temp_convert_c2f(c));
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} else if to_convert.ends_with("f") {
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let f: f32 = to_convert
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.trim_end_matches('f')
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.parse()
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.expect("failed to parse temperature");
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println!("{}C", temp_convert_f2c(f));
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} else {
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eprintln!("ERROR: What are we supposed to do to {:?}?", to_convert);
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}
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}
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fn temp_convert_c2f(c: f32) -> f32 {
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(c * (9.0 / 5.0)) + 32.0
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}
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fn temp_convert_f2c(f: f32) -> f32 {
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(f - 32.0) * (5.0 / 9.0)
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}
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fn fib_n(n: u64) {
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println!("{}", fib_up_to(n));
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}
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fn fib_up_to(n: u64) -> u64 {
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match n {
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0 => 0,
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1 => 1,
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_ => fib_up_to(n - 1) + fib_up_to(n - 2),
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}
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}
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