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| <h3 class="section">2.18 <code>getenv</code>—look up environment variable</h3> |
| |
| <p><a name="index-getenv-31"></a><a name="index-environ-32"></a><strong>Synopsis</strong> |
| <pre class="example"> #include <stdlib.h> |
| char *getenv(const char *<var>name</var>); |
| |
| </pre> |
| <p><strong>Description</strong><br> |
| <code>getenv</code> searches the list of environment variable names and values |
| (using the global pointer “<code>char **environ</code>”) for a variable whose |
| name matches the string at <var>name</var>. If a variable name matches, |
| <code>getenv</code> returns a pointer to the associated value. |
| |
| <p><br> |
| <strong>Returns</strong><br> |
| A pointer to the (string) value of the environment variable, or |
| <code>NULL</code> if there is no such environment variable. |
| |
| <p><br> |
| <strong>Portability</strong><br> |
| <code>getenv</code> is ANSI, but the rules for properly forming names of environment |
| variables vary from one system to another. |
| |
| <p><code>getenv</code> requires a global pointer <code>environ</code>. |
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