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| <h4 class="subsection">12.14.9 Variable Arguments Input Functions</h4> |
| |
| <p>The functions <code>vscanf</code> and friends are provided so that you can |
| define your own variadic <code>scanf</code>-like functions that make use of |
| the same internals as the built-in formatted output functions. |
| These functions are analogous to the <code>vprintf</code> series of output |
| functions. See <a href="Variable-Arguments-Output.html#Variable-Arguments-Output">Variable Arguments Output</a>, for important |
| information on how to use them. |
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| <p><strong>Portability Note:</strong> The functions listed in this section were |
| introduced in ISO C99<!-- /@w --> and were before available as GNU extensions. |
| |
| <!-- stdio.h --> |
| <!-- ISO --> |
| <div class="defun"> |
| — Function: int <b>vscanf</b> (<var>const char *template, va_list ap</var>)<var><a name="index-vscanf-1089"></a></var><br> |
| <blockquote><p>This function is similar to <code>scanf</code>, but instead of taking |
| a variable number of arguments directly, it takes an argument list |
| pointer <var>ap</var> of type <code>va_list</code> (see <a href="Variadic-Functions.html#Variadic-Functions">Variadic Functions</a>). |
| </p></blockquote></div> |
| |
| <!-- wchar.h --> |
| <!-- ISO --> |
| <div class="defun"> |
| — Function: int <b>vwscanf</b> (<var>const wchar_t *template, va_list ap</var>)<var><a name="index-vwscanf-1090"></a></var><br> |
| <blockquote><p>This function is similar to <code>wscanf</code>, but instead of taking |
| a variable number of arguments directly, it takes an argument list |
| pointer <var>ap</var> of type <code>va_list</code> (see <a href="Variadic-Functions.html#Variadic-Functions">Variadic Functions</a>). |
| </p></blockquote></div> |
| |
| <!-- stdio.h --> |
| <!-- ISO --> |
| <div class="defun"> |
| — Function: int <b>vfscanf</b> (<var>FILE *stream, const char *template, va_list ap</var>)<var><a name="index-vfscanf-1091"></a></var><br> |
| <blockquote><p>This is the equivalent of <code>fscanf</code> with the variable argument list |
| specified directly as for <code>vscanf</code>. |
| </p></blockquote></div> |
| |
| <!-- wchar.h --> |
| <!-- ISO --> |
| <div class="defun"> |
| — Function: int <b>vfwscanf</b> (<var>FILE *stream, const wchar_t *template, va_list ap</var>)<var><a name="index-vfwscanf-1092"></a></var><br> |
| <blockquote><p>This is the equivalent of <code>fwscanf</code> with the variable argument list |
| specified directly as for <code>vwscanf</code>. |
| </p></blockquote></div> |
| |
| <!-- stdio.h --> |
| <!-- ISO --> |
| <div class="defun"> |
| — Function: int <b>vsscanf</b> (<var>const char *s, const char *template, va_list ap</var>)<var><a name="index-vsscanf-1093"></a></var><br> |
| <blockquote><p>This is the equivalent of <code>sscanf</code> with the variable argument list |
| specified directly as for <code>vscanf</code>. |
| </p></blockquote></div> |
| |
| <!-- wchar.h --> |
| <!-- ISO --> |
| <div class="defun"> |
| — Function: int <b>vswscanf</b> (<var>const wchar_t *s, const wchar_t *template, va_list ap</var>)<var><a name="index-vswscanf-1094"></a></var><br> |
| <blockquote><p>This is the equivalent of <code>swscanf</code> with the variable argument list |
| specified directly as for <code>vwscanf</code>. |
| </p></blockquote></div> |
| |
| <p>In GNU C, there is a special construct you can use to let the compiler |
| know that a function uses a <code>scanf</code>-style format string. Then it |
| can check the number and types of arguments in each call to the |
| function, and warn you when they do not match the format string. |
| For details, see <a href="../gcc/Function-Attributes.html#Function-Attributes">Declaring Attributes of Functions</a>. |
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