# Compiler Symbol Definitions

> [HTML Version](compilersymboldefinitions.htm)

The following command line switch supports passing symbol definitions into the compiler. Syntax:

**/C:symbol \{=value\}**

**Example**

COMPIL MYPROG/RC/C:APPVER=2/C:GUI="VISTA"

This specifies the /RC switch, plus two instances of /C to define two symbols, APPVER=2 and GUI="VISTA". These definitions are treated exactly as if the following had been inserted at the top of the MYPROG source code:

define APPVER=2

define GUI="VISTA"



Note the need for quotes when defining a string symbol per the normal rules of the [DEFINE](define_compiler.md) statement.

If the =value clause not specified, it is treated as = 0, i.e. the symbol is defined (responds to ++IFDEF <symbol> but it has a null value.

**Example**

[COMPILER\_VERSION Macro](compiler_version_macro.md)