Answer 1

The default memory allocation for 'int' is usually 4 bytes (32 bits) in modern compilers and 2 bytes (16 bits) in the deprecated Turbo C++ Compiler.

__int32 is a Microsoft C++ specific keyword used to declare integers in a fixed bit range. Eg - __int32 declare 4 byte integers, __int16 declares 2 byte integers, etc.

Read more on these types:
https://msdn.microsoft.com/en-us/library/29dh1w7z.aspx

Note that these keywords are not available in Turbo C++. For GCC, there are other ways for getting specific bit integers, like <cstdint>

Bit Integers for GCC:
https://stackoverflow.com/questions/24308433/is-there-a-counterpart-of-int32-in-gcc