1.19. Defining a Macro
Problem
You want to define the preprocessor
symbol name, assigning it either an unspecified
value or the value value.
Solution
The compiler options for defining a macro from the command line are shown in Table 1-16. Instructions for defining a
macro from your IDE are given in Table
1-17. To define a macro using Boost.Build, simply add a property of the form
<define>name[=value] to your target’s requirements, as shown in Table 1-15 and Example 1-12.
Table 1-16. Defining a macro from the command line
|
Toolset |
Option |
|---|---|
|
All |
-D
|
Table 1-17. Defining a macro from your IDE
|
IDE |
Configuration |
|---|---|
|
Visual C++ |
From your project’s property pages, go to Configuration Properties → C/C++ → Preprocessor and enter
|
|
CodeWarrior |
From the Target Settings Window, go to Language Settings → C/C++ Preprocessor and enter:
in the area labeled Prefix Text. |
|
C++Builder |
From Project Options, go to Directories/Conditionals and enter
|
|
Dev-C++ |
From Project Options, select Parameters and enter:
under C++ Compiler. |
Discussion
Preprocessor symbols are used frequently in C++ source code to allow a single collection of source files to be used with several build configurations or operating systems. For example, suppose you want to write a function that checks ...