The compiler includes warnings that are off by default. If a warning is off by default, most users would not want to see such warnings for their code. However, some users would be interested to see such output from the compiler.
A warning that is off by default can be enabled in one of several ways:
#pragma warning(default :warning_number)
The warning is enabled at its default level. Documentation for the warning contains the default level of the warning.
#pragma warning(warning_level:warning_number)
The warning is enabled at the specified level (warning_level).
/Wall
This compiler option enables all warnings that are off by default.
