Rollup merge of #34804 - GuillaumeGomez:fix_ret, r=steveklabnik

Add examples for FpCategory

Fixes #29364.

r? @steveklabnik

Author: GuillaumeGomez

src/libcore/num/mod.rs

@@ -2308,26 +2308,45 @@ impl usize {
 ///
 /// [`f32::classify()`]: ../../std/primitive.f32.html#method.classify
 /// [`f64::classify()`]: ../../std/primitive.f64.html#method.classify
+///
+/// # Examples
+///
+/// ```
+/// use std::num::FpCategory;
+/// use std::f32;
+///
+/// let num = 12.4_f32;
+/// let inf = f32::INFINITY;
+/// let zero = 0f32;
+/// let sub: f32 = 0.000000000000000000000000000000000000011754942;
+/// let nan = f32::NAN;
+///
+/// assert_eq!(num.classify(), FpCategory::Normal);
+/// assert_eq!(inf.classify(), FpCategory::Infinite);
+/// assert_eq!(zero.classify(), FpCategory::Zero);
+/// assert_eq!(nan.classify(), FpCategory::Nan);
+/// assert_eq!(sub.classify(), FpCategory::Subnormal);
+/// ```
 #[derive(Copy, Clone, PartialEq, Debug)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub enum FpCategory {
-    /// "Not a Number", often obtained by dividing by zero
+    /// "Not a Number", often obtained by dividing by zero.
     #[stable(feature = "rust1", since = "1.0.0")]
     Nan,
 
-    /// Positive or negative infinity
+    /// Positive or negative infinity.
     #[stable(feature = "rust1", since = "1.0.0")]
     Infinite ,
 
-    /// Positive or negative zero
+    /// Positive or negative zero.
     #[stable(feature = "rust1", since = "1.0.0")]
     Zero,
 
-    /// De-normalized floating point representation (less precise than `Normal`)
+    /// De-normalized floating point representation (less precise than `Normal`).
     #[stable(feature = "rust1", since = "1.0.0")]
     Subnormal,
 
-    /// A regular floating point number
+    /// A regular floating point number.
     #[stable(feature = "rust1", since = "1.0.0")]
     Normal,
 }