1. You can try GetSystemTime() as follows:

SYSTEMTIME currentTime;
int second, minute;
GetSystemTime(&currentTime);

second = currentTime.wSecond;
minute = currentTime.wMinute;
.......

2. I don't know how you define the string ldfnm. You should define char ldfnm[30], or something like that, to allocate memory. Otherwise you may get an error.
Assertion is a debug method. The statement is like : assert(x==1). if x does not equal to 1, the program will raise an assertion failure. It can help you to debug the program. There are a lot of assertion statement in the C/C++ library to help you debug your programm.