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| <title>The GNU Fortran Compiler: Internal representation of LOGICAL variables</title> |
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| <a name="Internal-representation-of-LOGICAL-variables"></a> |
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| <a name="Internal-representation-of-LOGICAL-variables-1"></a> |
| <h3 class="section">5.2 Internal representation of LOGICAL variables</h3> |
| <a name="index-logical_002c-variable-representation"></a> |
| |
| <p>The Fortran standard does not specify how variables of <code>LOGICAL</code> |
| type are represented, beyond requiring that <code>LOGICAL</code> variables |
| of default kind have the same storage size as default <code>INTEGER</code> |
| and <code>REAL</code> variables. The GNU Fortran internal representation is |
| as follows. |
| </p> |
| <p>A <code>LOGICAL(KIND=N)</code> variable is represented as an |
| <code>INTEGER(KIND=N)</code> variable, however, with only two permissible |
| values: <code>1</code> for <code>.TRUE.</code> and <code>0</code> for |
| <code>.FALSE.</code>. Any other integer value results in undefined behavior. |
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| <p>See also <a href="Argument-passing-conventions.html#Argument-passing-conventions">Argument passing conventions</a> and <a href="Interoperability-with-C.html#Interoperability-with-C">Interoperability with C</a>. |
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