External environment refers to the major factors and forces outside the organization that have the potential to significantly affect the performance of an organization. External environment is divided into two parts i.e. mega environment or general environment and specific or task environment.
_tcscat is a C function, to concatenate C-style strings; CString is a class (which has built in concatenation via operator+), not a C-style string.
It means to include the header file conio.h in your C/C++ program. conio.h is a header file used in old MS-DOS compilers to create text user interfaces. It is not part of the C programming language, the C standard library, ISO C nor is it required by POSIX. This header declares several useful library functions for performing console input and output from a program.