Finished quiz 4 - dealing with errors

exercises/021_errors.zig

@@ -9,7 +9,7 @@
 // "TooSmall". Please add it where needed!
 const MyNumberError = error{
     TooBig,
-    ???,
+    TooSmall,
     TooFour,
 };
 
@@ -26,7 +26,7 @@ pub fn main() void {
         if (number_error == MyNumberError.TooBig) {
             std.debug.print(">4. ", .{});
         }
-        if (???) {
+        if (number_error == MyNumberError.TooSmall) {
             std.debug.print("<4. ", .{});
         }
         if (number_error == MyNumberError.TooFour) {

exercises/022_errors2.zig

@@ -19,8 +19,7 @@ const std = @import("std");
 const MyNumberError = error{TooSmall};
 
 pub fn main() void {
-    var my_number: ??? = 5;
+    var my_number: MyNumberError!usize = 5;
-
     // Looks like my_number will need to either store a number OR
     // an error. Can you set the type correctly above?
     my_number = MyNumberError.TooSmall;

exercises/023_errors3.zig

@@ -12,14 +12,14 @@ const MyNumberError = error{TooSmall};
 
 pub fn main() void {
     const a: u32 = addTwenty(44) catch 22;
-    const b: u32 = addTwenty(4) ??? 22;
+    const b: u32 = addTwenty(4) catch 22;
 
     std.debug.print("a={}, b={}\n", .{ a, b });
 }
 
 // Please provide the return type from this function.
 // Hint: it'll be an error union.
-fn addTwenty(n: u32) ??? {
+fn addTwenty(n: u32) MyNumberError!u32 {
     if (n < 5) {
         return MyNumberError.TooSmall;
     } else {

exercises/024_errors4.zig

@@ -53,13 +53,19 @@ fn fixTooBig(n: u32) MyNumberError!u32 {
 }
 
 fn fixTooSmall(n: u32) MyNumberError!u32 {
+    return detectProblems(n) catch |err| {
+        if (err == MyNumberError.TooSmall) {
+            return 10;
+        }
+
+        return err;
+    };
     // Oh dear, this is missing a lot! But don't worry, it's nearly
     // identical to fixTooBig() above.
     //
     // If we get a TooSmall error, we should return 10.
     // If we get any other error, we should return that error.
     // Otherwise, we return the u32 number.
-    return detectProblems(n) ???;
 }
 
 fn detectProblems(n: u32) MyNumberError!u32 {

exercises/025_errors5.zig

@@ -25,9 +25,7 @@ pub fn main() void {
 fn addFive(n: u32) MyNumberError!u32 {
     // This function needs to return any error which might come back from detect().
     // Please use a "try" statement rather than a "catch".
-    //
+    const x = try detect(n);
-    const x = detect(n);
-
     return x + 5;
 }
 

exercises/026_hello2.zig

@@ -23,5 +23,5 @@ pub fn main() !void {
     // to be able to pass it up as a return value of main().
     //
     // We just learned of a single statement which can accomplish this.
-    stdout.print("Hello world!\n", .{});
+    try stdout.print("Hello world!\n", .{});
 }

exercises/027_defer.zig

@@ -20,6 +20,6 @@ const std = @import("std");
 pub fn main() void {
     // Without changing anything else, please add a 'defer' statement
     // to this code so that our program prints "One Two\n":
-    std.debug.print("Two\n", .{});
+    defer std.debug.print("Two\n", .{});
     std.debug.print("One ", .{});
 }

exercises/028_defer2.zig

@@ -18,7 +18,7 @@ pub fn main() void {
 fn printAnimal(animal: u8) void {
     std.debug.print("(", .{});
 
-    std.debug.print(") ", .{}); // <---- how?!
+    defer std.debug.print(") ", .{}); // <---- how?!
 
     if (animal == 'g') {
         std.debug.print("Goat", .{});

exercises/029_errdefer.zig

@@ -32,7 +32,7 @@ fn makeNumber() MyErr!u32 {
 
     // Please make the "failed" message print ONLY if the makeNumber()
     // function exits with an error:
-    std.debug.print("failed!\n", .{});
+    errdefer std.debug.print("failed!\n", .{});
 
     var num = try getNumber(); // <-- This could fail!
 

exercises/030_switch.zig

@@ -46,6 +46,9 @@ pub fn main() void {
             // match for every possible value).  Please add an "else"
             // to this switch to print a question mark "?" when c is
             // not one of the existing matches.
+            else => {
+                std.debug.print("?", .{});
+            },
         }
     }
 

exercises/031_switch2.zig

@@ -31,6 +31,9 @@ pub fn main() void {
             26 => 'Z',
             // As in the last exercise, please add the 'else' clause
             // and this time, have it return an exclamation mark '!'.
+            else => {
+                return std.debug.print("!", .{});
+            },
         };
 
         std.debug.print("{c}", .{real_char});

exercises/032_unreachable.zig

@@ -35,6 +35,9 @@ pub fn main() void {
             3 => {
                 current_value *= current_value;
             },
+            else => {
+                unreachable;
+            },
         }
 
         std.debug.print("{} ", .{current_value});

exercises/033_iferror.zig

@@ -39,6 +39,7 @@ pub fn main() void {
             std.debug.print("={}. ", .{value});
         } else |err| switch (err) {
             MyNumberError.TooBig => std.debug.print(">4. ", .{}),
+            MyNumberError.TooSmall => std.debug.print("<4. ", .{}),
             // Please add a match for TooSmall here and have it print: "<4. "
         }
     }

exercises/034_quiz4.zig

@@ -9,10 +9,16 @@ const std = @import("std");
 
 const NumError = error{IllegalNumber};
 
-pub fn main() void {
+pub fn main() !void {
     const stdout = std.io.getStdOut().writer();
 
-    const my_num: u32 = getNumber();
+    const my_num: u32 = try getNumber();
+
+    // if (my_num) |value| {
+    // stdout("ZIG! {!}", .{value});
+    // } else |err| switch (err) {
+    // NumError.IllegalNumber => 42,
+    // }
 
     try stdout.print("my_num={}\n", .{my_num});
 }