initial commit

src/date_format.h

@@ -0,0 +1,29 @@
+#pragma once
+
+#include <ctime>
+#include <string>
+#include <vector>
+
+namespace radiantwave::datetime {
+
+// Default date format (US convention): MM/DD/YYYY.
+constexpr const char* DEFAULT_DATE_FORMAT = "%m/%d/%Y";
+
+// One selectable date format. `name` is a human-friendly convention label;
+// `pattern` is the strftime spec used to render it.
+struct DateFormatOption {
+    std::string name;
+    std::string pattern;
+};
+
+// The formats offered to the end user, ordered most-to-least common.
+std::vector<DateFormatOption> getDateFormatOptions();
+
+// Render `t` in local time using a strftime pattern (e.g. "%m/%d/%Y").
+// Falls back to an empty string on error.
+std::string formatDate(std::time_t t, const std::string& pattern);
+
+// Render `t` as a 24-hour clock: HH:MM:SS.
+std::string formatTime(std::time_t t);
+
+} // namespace radiantwave::datetime