Added ex 21-26 for error handling

25_errors5.zig

@@ -0,0 +1,40 @@
+//
+// Zig has a handy "try" shortcut for this common error handling pattern:
+//
+//     canFail() catch |err| return err;
+//
+// which can be more compactly written as:
+//
+//     try canFail();
+//
+const std = @import("std");
+
+const MyNumberError = error{
+    TooSmall,
+    TooBig,
+};
+
+pub fn main() void {
+    var a: u32 = addFive(44) catch 0;
+    var b: u32 = addFive(14) catch 0;
+    var c: u32 = addFive(4)  catch 0;
+
+    std.debug.print("a={}, b={}, c={}", .{a,b,c});
+}
+
+fn addFive(n: u32) MyNumberError!u32 {
+    //
+    // This function needs to return any error which might come back from fix().
+    // Please use a "try" statement rather than a "catch".
+    //
+    var x = detect(n);
+
+    return x + 5;
+}
+
+fn detect(n: u32) MyNumberError!u32 {
+    if (n < 10) return MyNumberError.TooSmall;
+    if (n > 20) return MyNumberError.TooBig;
+    return n;
+}
+