C # base -- preprocessing command

Preprocessing commands are mainly used to influenceProgramTo provide the compilation information or prohibited part.CodeC # does not have the same independent pre-processor as C ++, and the pre-processing commands are also processed by the compiler.

1. # define, # UNDEF is used to declare or delete symbol definitions. # define and # UNDEF must be placed in the first line of the file, and the defined symbols (variables) are valid only within the current file range.

2. # If, # Elif, # else, # endif is used to determine whether the identified code block needs to be compiled based on the defined symbols/variables. If not, it is not compiled, the generated executable file will be reduced accordingly.

  # define  debug  using  system;  using  system. collections. generic;  using  system. LINQ;  using  system. text;  namespace  client { class   defineclass  { Public static void  Print () {# If  DEBUG = false  console. writeline ("print");  #endif }}