/reference:file[;file2]
where:
The /reference option causes the compiler to make public type information in the specified files available to the project you are currently compiling.
The file(s) you import must contain a manifest; the output file must have been compiled with one of the /target options other than /target:module.
Use /addmodule to import metadata from an output file that does not contain an assembly manifest.
/r is the short form of /reference.
Compile source file input.cs
and import metadata from metad1.dll
and metad2.dll
to produce out.exe
:
csc /reference:metad1.dll;metad2.dll /out:out.exe input.cs