Merge pull request #2 from byte911/main

Add 03-01 elapsed time

.github/workflows/ci.yml

@@ -29,9 +29,13 @@ jobs:
       - name: Run examples(Unix)
         if: matrix.os != 'windows-latest'
         working-directory: examples
-        run: zig build run-all --summary all
+        run: |
+          zig fmt --check src/
+          zig build run-all --summary all
 
       - name: Run examples(Windows)
         if: matrix.os == 'windows-latest'
         working-directory: examples
-        run: zig.exe build run-all --summary all
+        run: |
+          zig.exe fmt --check src/
+          zig.exe build run-all --summary all

.gitignore

@@ -1,3 +1,4 @@
 book
 zig-out/
 zig-cache/
+.DS_Store

examples/src/03-01.zig

@@ -0,0 +1,20 @@
+const std = @import("std");
+const time = std.time;
+const Instant = time.Instant;
+const print = std.debug.print;
+
+fn expensive_function() void {
+    // sleep 500ms
+    time.sleep(time.ns_per_ms * 500);
+}
+
+pub fn main() !void {
+    const start = try Instant.now();
+    expensive_function();
+    const now = try Instant.now();
+    const elapsed_ns: f64 = @floatFromInt(now.since(start));
+
+    print("Time elapsed in expensive_function() is: {d:.3}ms", .{
+        elapsed_ns / time.ns_per_s,
+    });
+}

src/03-01-elapsed-time.md

@@ -0,0 +1,34 @@
+### Measure the elapsed time between two code sections
+
+Measures [`std.time.Instant.since`] since [`std.time.Instant.now`].
+
+Calling [`std.time.Instant.since`] returns a u64 representing nanoseconds elapsed.
+
+```zig
+const std = @import("std");
+const time = std.time;
+const Instant = time.Instant;
+const print = std.debug.print;
+
+fn expensive_function() void {
+    // sleep 500ms
+    time.sleep(time.ns_per_ms * 500);
+}
+
+pub fn main() !void {
+    const start = try Instant.now();
+    expensive_function();
+    const now = try Instant.now();
+    const elapsed_ns: f64 = @floatFromInt(now.since(start));
+
+    print("Time elapsed in expensive_function() is: {d:.3}ms", .{
+        elapsed_ns / time.ns_per_s,
+    });
+}
+```
+
+[`std.time.ns_per_s`]: https://ziglang.org/documentation/master/std/#A;std:time.ns_per_s
+[`std.time.Instant.since`]: https://ziglang.org/documentation/master/std/#A;std:time.Instant.since
+[`std.time.Instant.now`]: https://ziglang.org/documentation/master/std/#A;std:time.Instant.now
+[`std.time.Instant`]:https://ziglang.org/documentation/master/std/#A;std:time.Instant
+ Measure the elapsed time

src/SUMMARY.md

@@ -8,3 +8,6 @@
 
 - [Cryptography]()
   - [Calculate SHA-256 digest of a file](./02-01-sha-digest.md)
+
+- [Date and Time]()
+  - [Measure the elapsed time between two code sections](./03-01-elapsed-time.md)