Inserted ex. 32 unreachable, added quiz4.

1 files changed, 49 insertions, 0 deletions

diff --git a/33_iferror.zig b/33_iferror.zig
new file mode 100644
index 0000000..ed92e94
--- /dev/null
+++ b/33_iferror.zig
@@ -0,0 +1,49 @@
+//
+// Let's revisit the very first error exercise. This time, we're going to
+// look at a special error-handling type of the "if" statement.
+//
+//     if (foo) |value| {
+//
+//         // foo was NOT an error; value is the non-error value of foo
+//
+//     } else |err| {
+//
+//         // foo WAS an error; err is the error value of foo
+//
+//     }
+//
+// We'll take it even further and use a switch statement to handle
+// the error types.
+//
+const MyNumberError = error{
+    TooBig,
+    TooSmall,
+};
+
+const std = @import("std");
+
+pub fn main() void {
+    var nums = [_]u8{2,3,4,5,6};
+
+    for (nums) |num| {
+        std.debug.print("{}", .{num});
+
+        var n = numberMaybeFail(num);
+        if (n) |value| {
+            std.debug.print("=4. ", .{});
+        } else |err| switch (err) {
+            MyNumberError.TooBig   => std.debug.print(">4. ", .{}),
+            // Please add a match for TooSmall here and have it print: "<4. "
+        }
+    }
+
+    std.debug.print("\n", .{});
+}
+
+// This time we'll have numberMaybeFail() return an error union rather
+// than a straight error.
+fn numberMaybeFail(n: u8) MyNumberError!u8 {
+    if(n > 4) return MyNumberError.TooBig;
+    if(n < 4) return MyNumberError.TooSmall;
+    return n;
+}