Price fraction: Difference between revisions

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@@ Line 2,586: / Line 2,586: @@
 =={{header|Rust}}==
-<lang rust>fn fix_price(n: f64) -> f64 {
+<lang rust>fn fix_price(num: f64) -> f64 {
+    match num {
-    let ranges: Vec<(f64, f64, f64)> = vec![
-        (0.00, 0.06, 0.10),
+.96...1.00 => 1.00,
-        (0.06, 0.11, 0.18),
+.91...0.96 => 0.98,
-        (0.11, 0.16, 0.26),
+.86...0.91 => 0.94,
-        (0.16, 0.21, 0.32),
+.81...0.86 => 0.90,
-        (0.21, 0.26, 0.38),
+.76...0.81 => 0.86,
-        (0.26, 0.31, 0.44),
+.71...0.76 => 0.82,
-        (0.31, 0.36, 0.50),
+.66...0.71 => 0.78,
-        (0.36, 0.41, 0.54),
+.61...0.66 => 0.74,
-        (0.41, 0.46, 0.58),
+.56...0.61 => 0.70,
-        (0.46, 0.51, 0.62),
+.51...0.56 => 0.66,
-        (0.51, 0.56, 0.66),
+.46...0.51 => 0.62,
-        (0.56, 0.61, 0.70),
+.41...0.46 => 0.58,
-        (0.61, 0.66, 0.74),
+.36...0.41 => 0.54,
-        (0.66, 0.71, 0.78),
+.31...0.36 => 0.50,
-        (0.71, 0.76, 0.82),
+.26...0.31 => 0.44,
-        (0.76, 0.81, 0.86),
+.21...0.26 => 0.38,
-        (0.81, 0.86, 0.90),
+.16...0.21 => 0.32,
-        (0.86, 0.91, 0.94),
+.11...0.16 => 0.26,
-        (0.91, 0.96, 0.98),
+.06...0.11 => 0.18,
-        (0.96, 1.01, 1.00)
+.00...0.06 => 0.10,
+        // panics on invalid value
-    ];
-    for &(b, e, a) in ranges.iter() {
+        _ => unreachable!(),
-        if n >= b && n < e { return a; }
     }
-.00
 }
 fn main() {
     let mut n: f64 = 0.04;
-    while n <= 1.01 {
+    while n <= 1.00 {
-        println!("{} => {}", n, fix_price(n));
+        println!("{:.2} => {}", n, fix_price(n));
-        n += 0.05;
+        n += 0.04;
+    }
+}
+// and a unit test to check that we haven't forgotten a branch, use 'cargo test' to execute test.
+//
+// typically this could be included in the match as those check for exhaustiveness already
+// by explicitly listing all remaining ranges / values instead of a catch-all underscore (_)
+// but f64::NaN, f64::INFINITY and f64::NEG_INFINITY can't be matched like this
+#[test]
+fn exhaustiveness_check() {
+    let mut input_price = 0.;
+    while input_price <= 1. {
+        fix_price(input_price);
+        input_price += 0.01;
     }
 }</lang>
@@ Line 2,645: / Line 2,657: @@
 .94 => 0.98
 .99 => 1</pre>
+'''Output of unit test:'''
+<pre>
+running 1 test
+test exhaustiveness_check ... ok
+test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured</pre>
 =={{header|Scala}}==