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| <tt>SWIG/Examples/java/constants/</tt> |
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| <H2>Wrapping C Constants</H2> |
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| <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. |
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| <h2>Accessing Constants from Java</h2> |
| Click <a href="../../../Doc/Manual/Java.html#constants">here</a> for the section on constants in the SWIG and Java documentation. |
| <p> |
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| 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.</p> |
| <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 |
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| </blockquote> |
| is ignored because SWIG has no idea what type of variable this would be. |
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| <p> |
| <li>Expressions are allowed provided that all of their components are defined. Otherwise, the constant is ignored. |
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| <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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