Update Zig Cat Example

* Added file open error handling, by catching an error.
* Added better streamUntilDelimiter error handling. You can try,
  but you can't catch.
* Use ArrayList's writer to dynamically allocate space needed to
  read a line.

zig-cat/src/main.zig

@@ -3,24 +3,26 @@ const std = @import("std");
 pub fn main() !void {
     for (std.os.argv[1..]) |file_path_sent| {
         const file_path = std.mem.span(file_path_sent);
-        const file = try std.fs.openFileAbsolute(
+        const file = std.fs.openFileAbsolute(
             file_path,
             .{ .mode = .read_only },
-        );
+        ) catch |err| {
+            std.debug.print("error occurred while opening file: {s}\n", .{@errorName(err)});
+            return;
+        };
         defer file.close();
 
         while (true) {
-            const rw_result = file.reader().streamUntilDelimiter(
-                std.io.getStdOut().writer(),
+            var ar = std.ArrayList(u8).init(std.heap.page_allocator);
+            defer ar.deinit();
+
+            file.reader().streamUntilDelimiter(
+                ar.writer(),
                 '\n',
                 null,
-            );
+            ) catch break;
 
-            if (rw_result) |_| {} else |_| {
-                break;
-            }
-
-            std.debug.print("\n", .{});
+            std.debug.print("{s}\n", .{ar.items});
         }
     }
 }