Preprocessor directives in C# are special instructions that are processed by the compiler before the actual compilation starts[1][2][3]. They begin with a # symbol and are used to control various aspects of the compilation process[1][2].
The main preprocessor directives in C# are:
#define: Defines a symbol that can be used in conditional compilation[1][2][3]
#undef: Undefines a previously defined symbol[1][2][3]
#if, #elif, #else, #endif: Used for conditional compilation based on defined symbols[1][2][3][5]
#line: Modifies the line number and file name reported by the compiler for errors and warnings[3]
#error: Generates a compile-time error with a custom message[3]
#warning: Generates a compile-time warning with a cust...
