Create arithmetic.c

datetime/arithmetic.c

@@ -0,0 +1,30 @@
+#include <windows.h>
+#include <wchar.h>
+
+#define NSECS 60*60*3
+
+int wmain(void) {
+
+    SYSTEMTIME st = {0};
+    FILETIME ft = {0};
+
+    GetLocalTime(&st);
+
+    wprintf(L"%02d/%02d/%04d %02d:%02d:%02d\n",
+        st.wDay, st.wMonth, st.wYear, st.wHour, st.wMinute, st.wSecond);
+
+    SystemTimeToFileTime(&st, &ft);
+
+    ULARGE_INTEGER u = {0};
+     
+    memcpy(&u, &ft, sizeof(u));
+    u.QuadPart += NSECS * 10000000LLU;
+    memcpy(&ft, &u, sizeof(ft));
+
+    FileTimeToSystemTime(&ft, &st);
+
+    wprintf(L"%02d/%02d/%04d %02d:%02d:%02d\n",
+        st.wDay,st.wMonth,st.wYear,st.wHour,st.wMinute,st.wSecond);
+
+    return 0;
+}