add optional

Author: ziteh

optional/basic.zig

@@ -0,0 +1,11 @@
+const std = @import("std");
+
+pub fn main() void {
+    var value: ?u8 = null;
+    std.debug.print("Value: {?}\n", .{value});
+
+    if (value == null) {
+        value = 32;
+    }
+    std.debug.print("Value: {?}", .{value});
+}

optional/orelse.zig

@@ -0,0 +1,14 @@
+const std = @import("std");
+
+pub fn main() void {
+    var a: ?u8 = null;
+    const b: u8 = 32;
+    var c = a orelse b;
+    std.debug.print("Value: {}\n", .{c});
+
+    a = 128;
+    c = a orelse b;
+    std.debug.print("Value: {}\n", .{c});
+
+    std.debug.print("Type: {}", .{@TypeOf(c)});
+}

optional/readme.md

@@ -0,0 +1,20 @@
+# Optional
+
+```bash
+$ zig run basic.zig
+Value: null
+Value: 32
+```
+
+```bash
+$ zig run orelse.zig
+Value: 32
+Value: 128
+Type: u8
+```
+
+```bash
+$ zig run unreachable.zig
+Value: 32
+thread 55352 panic: attempt to use null value
+```

optional/unreachable.zig

@@ -0,0 +1,11 @@
+const std = @import("std");
+
+pub fn main() void {
+    var a: ?u8 = 32;
+    var c = a.?;
+    std.debug.print("Value: {}\n", .{c});
+
+    a = null;
+    c = a.?; // painc!
+    std.debug.print("Value: {}\n", .{c});
+}