From SYSTEMTIME to cstring

Since the system time is already available in a structure, you can simply output it in a C-String using snprintf(). The minimum length for a 4-digit year should be 38 characters.

// SYSTEMTIME lt;
const char* days[] = { "Sunday", ... };
const char* months[] = { .. };
#define MAXOUTPUTLEN 40
char outputString[MAXOUTPUTLEN];
snprintf(outputString, sizeof(outputString), 
     "%s %d %s %d, %02d:%02d:%02d", days[lt.wDayOfWeek], ...

It would also be possible to calculate the length with snprintf in order to reserve an optimally fitting C-string.