Create days_to_xmas.c

datetime/days_to_xmas.c

@@ -0,0 +1,49 @@
+#include <windows.h>
+#include <wchar.h>
+
+int wmain(void) {
+
+    FILETIME ft1 = {0};
+    FILETIME ft2 = {0};
+    SYSTEMTIME st = {0};  
+    LARGE_INTEGER li1 = {0};    
+    LARGE_INTEGER li2 = {0}; 
+
+    st.wYear = 2016;
+    st.wMonth = 12;
+    st.wDay = 25;
+
+    int r = SystemTimeToFileTime(&st, &ft1);
+
+    if (r == 0) {
+
+        wprintf(L"Failed to convert system time to file time\n (%d)", 
+            GetLastError());
+        return 1;
+    }
+
+    GetSystemTimeAsFileTime(&ft2);
+
+    li1.LowPart = ft1.dwLowDateTime;
+    li1.HighPart = ft1.dwHighDateTime;
+
+    li2.LowPart = ft2.dwLowDateTime;
+    li2.HighPart = ft2.dwHighDateTime;
+
+    long long int dif = li1.QuadPart - li2.QuadPart;
+
+    int days2xmas = dif / 10000000L / 60 / 60 / 24;
+
+    if (days2xmas == 1) {
+
+        wprintf(L"There is one day until Christmas\n", days2xmas);
+    } else if (days2xmas == 0) {
+
+        wprintf(L"Today is Chritmas\n");
+    } else {
+
+        wprintf(L"There are %d days until Christmas\n", days2xmas);
+    }
+
+    return 0;
+}