/tags/rel-1-3-26/SWIG/Examples/java/constants/index.html
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- <title>SWIG:Examples:java:constants</title>
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- <tt>SWIG/Examples/java/constants/</tt>
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- <H2>Wrapping C Constants</H2>
- <tt>$Header$</tt><br>
- <p>
- When SWIG encounters C preprocessor macros and C declarations that look like constants,
- it creates Java constant with an identical value. Click <a href="example.i">here</a>
- to see a SWIG interface with some constant declarations in it.
- <h2>Accessing Constants from Java</h2>
- Click <a href="main.java">here</a> to see a Java program that prints out the values
- of the constants contained in the above file.
- <h2>Key points</h2>
- <ul>
- <li>The values of preprocessor macros are converted into Java constants.
- <li>Types are inferred by syntax (e.g., "3" is an integer and "3.5" is a float).
- <li>Character constants such as 'x' are converted into Java strings.
- <li>C string literals such as "Hello World" are converted into Java strings.
- <li>Macros that are not fully defined are simply ignored. For example:
- <blockquote>
- <pre>
- #define EXTERN extern
- </pre>
- </blockquote>
- is ignored because SWIG has no idea what type of variable this would be.
- <p>
- <li>Expressions are allowed provided that all of their components are defined. Otherwise, the constant is ignored.
- <li>Certain C declarations involving 'const' are also turned into Java constants.
- <li>The constants that appear in a SWIG interface file do not have to appear in any sort
- of matching C source file since the creation of a constant does not require linkage
- to a stored value (i.e., a value held in a C global variable or memory location).
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