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<h1 id="firstHeading" class="firstHeading">File input/output</h1> <p>The <code><stdio.h></code> header provides generic file operation support and supplies functions with narrow character input/output capabilities.</p>
<p>The <a href="string/wide" title="c/string/wide"><code><wchar.h></code></a> header supplies functions with wide character input/output capabilities.</p>
<p>I/O streams are denoted by objects of type <code><a href="io/file" title="c/io/FILE">FILE</a></code> that can only be accessed and manipulated through pointers of type <code><a href="http://en.cppreference.com/w/c/io/FILE"><span class="kw884">FILE</span></a><span class="sy2">*</span></code>. Each stream is associated with an external physical device (file, standard input stream, printer, serial port, etc).</p>
<h3 id="Types"> Types</h3> <table class="t-dsc-begin"> <tr class="t-dsc-header"> <th colspan="2"> Defined in header <code><stdio.h></code> </th>
</tr> <tr class="t-dsc"> <td> <div><a href="io/file" title="c/io/FILE"> <span class="t-lines"><span>FILE</span></span></a></div> </td> <td> object type, capable of holding all information needed to control a C I/O stream <br> <span class="t-mark">(typedef)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/fpos_t" title="c/io/fpos t"> <span class="t-lines"><span>fpos_t</span></span></a></div> </td> <td> non-array complete object type, capable of uniquely specifying a position and multibyte parser state in a file <br> <span class="t-mark">(typedef)</span> </td>
</tr> </table> <h3 id="Predefined_standard_streams"> Predefined standard streams</h3> <table class="t-dsc-begin"> <tr class="t-dsc-header"> <th colspan="2"> Defined in header <code><stdio.h></code> </th>
</tr> <tr class="t-dsc"> <td> <div><a href="io/std_streams" title="c/io/std streams"> <span class="t-lines"><span>stdin</span><span>stdout</span><span>stderr</span></span></a></div> </td> <td> expression of type <code><a href="http://en.cppreference.com/w/c/io/FILE"><span class="kw884">FILE</span></a><span class="sy2">*</span></code> associated with the input stream<br>expression of type <code><a href="http://en.cppreference.com/w/c/io/FILE"><span class="kw884">FILE</span></a><span class="sy2">*</span></code> associated with the output stream<br>expression of type <code><a href="http://en.cppreference.com/w/c/io/FILE"><span class="kw884">FILE</span></a><span class="sy2">*</span></code> associated with the error output stream <br> <span class="t-mark">(macro constant)</span> </td>
</tr> </table> <h3 id="Functions"> Functions</h3> <table class="t-dsc-begin"> <tr> <td colspan="2"> <h5 id="File_access"> File access </h5> </td>
</tr> <tr class="t-dsc-header"> <th colspan="2"> Defined in header <code><stdio.h></code> </th>
</tr> <tr class="t-dsc"> <td> <div><a href="io/fopen" title="c/io/fopen"> <span class="t-lines"><span>fopen</span><span>fopen_s</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div> </td> <td> opens a file <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/freopen" title="c/io/freopen"> <span class="t-lines"><span>freopen</span><span>freopen_s</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div> </td> <td> open an existing stream with a different name <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/fclose" title="c/io/fclose"> <span class="t-lines"><span>fclose</span></span></a></div> </td> <td> closes a file <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/fflush" title="c/io/fflush"> <span class="t-lines"><span>fflush</span></span></a></div> </td> <td> synchronizes an output stream with the actual file <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/setbuf" title="c/io/setbuf"> <span class="t-lines"><span>setbuf</span></span></a></div> </td> <td> sets the buffer for a file stream <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/setvbuf" title="c/io/setvbuf"> <span class="t-lines"><span>setvbuf</span></span></a></div> </td> <td> sets the buffer and its size for a file stream <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc-header"> <th colspan="2"> Defined in header <code><wchar.h></code> </th>
</tr> <tr class="t-dsc"> <td> <div><a href="io/fwide" title="c/io/fwide"> <span class="t-lines"><span>fwide</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c95">(C95)</span></span></span></div> </td> <td> switches a file stream between wide character I/O and narrow character I/O <br> <span class="t-mark">(function)</span> </td>
</tr> <tr> <td colspan="2"> <h5 id="Direct_input.2Foutput"> Direct input/output </h5> </td>
</tr> <tr class="t-dsc-header"> <th colspan="2"> Defined in header <code><stdio.h></code> </th>
</tr> <tr class="t-dsc"> <td> <div><a href="io/fread" title="c/io/fread"> <span class="t-lines"><span>fread</span></span></a></div> </td> <td> reads from a file <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/fwrite" title="c/io/fwrite"> <span class="t-lines"><span>fwrite</span></span></a></div> </td> <td> writes to a file <br> <span class="t-mark">(function)</span> </td>
</tr> <tr> <td colspan="2"> <h5 id="Unformatted_input.2Foutput"> Unformatted input/output </h5> </td>
</tr> <tr> <td colspan="2">
<h6 id="Narrow_character"> Narrow character</h6> </td>
</tr> <tr class="t-dsc-header"> <th colspan="2"> Defined in header <code><stdio.h></code> </th>
</tr> <tr class="t-dsc"> <td> <div><a href="io/fgetc" title="c/io/fgetc"> <span class="t-lines"><span>fgetc</span><span>getc</span></span></a></div> </td> <td> gets a character from a file stream <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/fgets" title="c/io/fgets"> <span class="t-lines"><span>fgets</span></span></a></div> </td> <td> gets a character string from a file stream <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/fputc" title="c/io/fputc"> <span class="t-lines"><span>fputc</span><span>putc</span></span></a></div> </td> <td> writes a character to a file stream <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/fputs" title="c/io/fputs"> <span class="t-lines"><span>fputs</span></span></a></div> </td> <td> writes a character string to a file stream <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/getchar" title="c/io/getchar"> <span class="t-lines"><span>getchar</span></span></a></div> </td> <td> reads a character from <code><a href="io/std_streams" title="c/io/std streams">stdin</a></code> <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/gets" title="c/io/gets"> <span class="t-lines"><span>gets</span><span>gets_s</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-until-c11">(removed in C11)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div> </td> <td> reads a character string from <code>stdin</code> <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/putchar" title="c/io/putchar"> <span class="t-lines"><span>putchar</span></span></a></div> </td> <td> writes a character to <code>stdout</code> <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/puts" title="c/io/puts"> <span class="t-lines"><span>puts</span></span></a></div> </td> <td> writes a character string to <code><a href="io/std_streams" title="c/io/std streams">stdout</a></code> <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/ungetc" title="c/io/ungetc"> <span class="t-lines"><span>ungetc</span></span></a></div> </td> <td> puts a character back into a file stream <br> <span class="t-mark">(function)</span> </td>
</tr> <tr> <td colspan="2">
<h6 id="Wide_character"> Wide character</h6> </td>
</tr> <tr class="t-dsc-header"> <th colspan="2"> Defined in header <code><wchar.h></code> </th>
</tr> <tr class="t-dsc"> <td> <div><a href="io/fgetwc" title="c/io/fgetwc"> <span class="t-lines"><span>fgetwc</span><span>getwc</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c95">(C95)</span></span></span></div> </td> <td> gets a wide character from a file stream <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/fgetws" title="c/io/fgetws"> <span class="t-lines"><span>fgetws</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c95">(C95)</span></span></span></div> </td> <td> gets a wide string from a file stream <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/fputwc" title="c/io/fputwc"> <span class="t-lines"><span>fputwc</span><span>putwc</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c95">(C95)</span></span></span></div> </td> <td> writes a wide character to a file stream <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/fputws" title="c/io/fputws"> <span class="t-lines"><span>fputws</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c95">(C95)</span></span></span></div> </td> <td> writes a wide string to a file stream <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/getwchar" title="c/io/getwchar"> <span class="t-lines"><span>getwchar</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c95">(C95)</span></span></span></div> </td> <td> reads a wide character from <code>stdin</code> <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/putwchar" title="c/io/putwchar"> <span class="t-lines"><span>putwchar</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c95">(C95)</span></span></span></div> </td> <td> writes a wide character to <code><a href="io/std_streams" title="c/io/std streams">stdout</a></code> <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/ungetwc" title="c/io/ungetwc"> <span class="t-lines"><span>ungetwc</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c95">(C95)</span></span></span></div> </td> <td> puts a wide character back into a file stream <br> <span class="t-mark">(function)</span> </td>
</tr> <tr> <td colspan="2"> <h5 id="Formatted_input.2Foutput"> Formatted input/output </h5> </td>
</tr> <tr> <td colspan="2">
<h6 id="Narrow_character_2"> Narrow character</h6> </td>
</tr> <tr class="t-dsc-header"> <th colspan="2"> Defined in header <code><stdio.h></code> </th>
</tr> <tr class="t-dsc"> <td> <div><a href="io/fscanf" title="c/io/fscanf"> <span class="t-lines"><span>scanf</span><span>fscanf</span><span>sscanf</span><span>scanf_s</span><span>fscanf_s</span><span>sscanf_s</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c11">(C11)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div> </td> <td> reads formatted input from <code><a href="io/std_streams" title="c/io/std streams">stdin</a></code>, a file stream or a buffer <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/vfscanf" title="c/io/vfscanf"> <span class="t-lines"><span>vscanf</span><span>vfscanf</span><span>vsscanf</span><span>vscanf_s</span><span>vfscanf_s</span><span>vsscanf_s</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c99">(C99)</span></span><span><span class="t-mark-rev t-since-c99">(C99)</span></span><span><span class="t-mark-rev t-since-c99">(C99)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div> </td> <td> reads formatted input from <code><a href="io/std_streams" title="c/io/std streams">stdin</a></code>, a file stream or a buffer<br> using variable argument list <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/fprintf" title="c/io/fprintf"> <span class="t-lines"><span>printf</span><span>fprintf</span><span>sprintf</span><span>snprintf</span><span>printf_s</span><span>fprintf_s</span><span>sprintf_s</span><span>snprintf_s</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c99">(C99)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div> </td> <td> prints formatted output to <code><a href="io/std_streams" title="c/io/std streams">stdout</a></code>, a file stream or a buffer <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/vfprintf" title="c/io/vfprintf"> <span class="t-lines"><span>vprintf</span><span>vfprintf</span><span>vsprintf</span><span>vsnprintf</span><span>vprintf_s</span><span>vfprintf_s</span><span>vsprintf_s</span><span>vsnprintf_s</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c99">(C99)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div> </td> <td> prints formatted output to <code><a href="io/std_streams" title="c/io/std streams">stdout</a></code>, a file stream or a buffer<br> using variable argument list <br> <span class="t-mark">(function)</span> </td>
</tr> <tr> <td colspan="2">
<h6 id="Wide_character_2"> Wide character</h6> </td>
</tr> <tr class="t-dsc-header"> <th colspan="2"> Defined in header <code><wchar.h></code> </th>
</tr> <tr class="t-dsc"> <td> <div><a href="io/fwscanf" title="c/io/fwscanf"> <span class="t-lines"><span>wscanf</span><span>fwscanf</span><span>swscanf</span><span>wscanf_s</span><span>fwscanf_s</span><span>swscanf_s</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c95">(C95)</span></span><span><span class="t-mark-rev t-since-c95">(C95)</span></span><span><span class="t-mark-rev t-since-c95">(C95)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div> </td> <td> reads formatted wide character input from <code><a href="io/std_streams" title="c/io/std streams">stdin</a></code>, a file stream or a buffer <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/vfwscanf" title="c/io/vfwscanf"> <span class="t-lines"><span>vwscanf</span><span>vfwscanf</span><span>vswscanf</span><span>vwscanf_s</span><span>vfwscanf_s</span><span>vswscanf_s</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c99">(C99)</span></span><span><span class="t-mark-rev t-since-c99">(C99)</span></span><span><span class="t-mark-rev t-since-c99">(C99)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div> </td> <td> reads formatted wide character input from <code><a href="io/std_streams" title="c/io/std streams">stdin</a></code>, a file stream<br> or a buffer using variable argument list <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/fwprintf" title="c/io/fwprintf"> <span class="t-lines"><span>wprintf</span><span>fwprintf</span><span>swprintf</span><span>wprintf_s</span><span>fwprintf_s</span><span>swprintf_s</span><span>snwprintf_s</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c95">(C95)</span></span><span><span class="t-mark-rev t-since-c95">(C95)</span></span><span><span class="t-mark-rev t-since-c95">(C95)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div> </td> <td> prints formatted wide character output to <code><a href="io/std_streams" title="c/io/std streams">stdout</a></code>, a file stream or a buffer <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/vfwprintf" title="c/io/vfwprintf"> <span class="t-lines"><span>vwprintf</span><span>vfwprintf</span><span>vswprintf</span><span>vwprintf_s</span><span>vfwprintf_s</span><span>vswprintf_s</span><span>vsnwprintf_s</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c95">(C95)</span></span><span><span class="t-mark-rev t-since-c95">(C95)</span></span><span><span class="t-mark-rev t-since-c95">(C95)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div> </td> <td> prints formatted wide character output to <code><a href="io/std_streams" title="c/io/std streams">stdout</a></code>, a file stream<br> or a buffer using variable argument list <br> <span class="t-mark">(function)</span> </td>
</tr> <tr> <td colspan="2"> <h5 id="File_positioning"> File positioning </h5> </td>
</tr> <tr class="t-dsc-header"> <th colspan="2"> Defined in header <code><stdio.h></code> </th>
</tr> <tr class="t-dsc"> <td> <div><a href="io/ftell" title="c/io/ftell"> <span class="t-lines"><span>ftell</span></span></a></div> </td> <td> returns the current file position indicator <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/fgetpos" title="c/io/fgetpos"> <span class="t-lines"><span>fgetpos</span></span></a></div> </td> <td> gets the file position indicator <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/fseek" title="c/io/fseek"> <span class="t-lines"><span>fseek</span></span></a></div> </td> <td> moves the file position indicator to a specific location in a file <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/fsetpos" title="c/io/fsetpos"> <span class="t-lines"><span>fsetpos</span></span></a></div> </td> <td> moves the file position indicator to a specific location in a file <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/rewind" title="c/io/rewind"> <span class="t-lines"><span>rewind</span></span></a></div> </td> <td> moves the file position indicator to the beginning in a file <br> <span class="t-mark">(function)</span> </td>
</tr> <tr> <td colspan="2"> <h5 id="Error_handling"> Error handling </h5> </td>
</tr> <tr class="t-dsc-header"> <th colspan="2"> Defined in header <code><stdio.h></code> </th>
</tr> <tr class="t-dsc"> <td> <div><a href="io/clearerr" title="c/io/clearerr"> <span class="t-lines"><span>clearerr</span></span></a></div> </td> <td> clears errors <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/feof" title="c/io/feof"> <span class="t-lines"><span>feof</span></span></a></div> </td> <td> checks for the end-of-file <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/ferror" title="c/io/ferror"> <span class="t-lines"><span>ferror</span></span></a></div> </td> <td> checks for a file error <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/perror" title="c/io/perror"> <span class="t-lines"><span>perror</span></span></a></div> </td> <td> displays a character string corresponding of the current error to <code><a href="io/std_streams" title="c/io/std streams">stderr</a></code> <br> <span class="t-mark">(function)</span> </td>
</tr> <tr> <td colspan="2"> <h5 id="Operations_on_files"> Operations on files </h5> </td>
</tr> <tr class="t-dsc-header"> <th colspan="2"> Defined in header <code><stdio.h></code> </th>
</tr> <tr class="t-dsc"> <td> <div><a href="io/remove" title="c/io/remove"> <span class="t-lines"><span>remove</span></span></a></div> </td> <td> erases a file <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/rename" title="c/io/rename"> <span class="t-lines"><span>rename</span></span></a></div> </td> <td> renames a file <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/tmpfile" title="c/io/tmpfile"> <span class="t-lines"><span>tmpfile</span><span>tmpfile_s</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div> </td> <td> returns a pointer to a temporary file <br> <span class="t-mark">(function)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><a href="io/tmpnam" title="c/io/tmpnam"> <span class="t-lines"><span>tmpnam</span><span>tmpnam_s</span></span></a></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div> </td> <td> returns a unique filename <br> <span class="t-mark">(function)</span> </td>
</tr> </table> <h3 id="Macro_constants"> Macro constants</h3> <table class="t-dsc-begin"> <tr class="t-dsc-header"> <th colspan="2"> Defined in header <code><stdio.h></code> </th>
</tr> <tr class="t-dsc"> <td> <div><span class="t-lines"><span>EOF</span></span></div> </td> <td> integer constant expression of type <code>int</code> and negative value <br> <span class="t-mark">(macro constant)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><span class="t-lines"><span>FOPEN_MAX</span></span></div> </td> <td> maximum number of files that can be open simultaneously <br> <span class="t-mark">(macro constant)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><span class="t-lines"><span>FILENAME_MAX</span></span></div> </td> <td> size needed for an array of <code>char</code> to hold the longest supported file name <br> <span class="t-mark">(macro constant)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><span class="t-lines"><span>BUFSIZ</span></span></div> </td> <td> size of the buffer used by <code><a href="io/setbuf" title="c/io/setbuf">setbuf</a></code> <br> <span class="t-mark">(macro constant)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><span class="t-lines"><span>_IOFBF</span><span>_IOLBF</span><span>_IONBF</span></span></div> </td> <td> argument to <code><a href="io/setvbuf" title="c/io/setvbuf">setvbuf</a></code> indicating fully buffered I/O<br>argument to <code><a href="io/setvbuf" title="c/io/setvbuf">setvbuf</a></code> indicating line buffered I/O<br>argument to <code><a href="io/setvbuf" title="c/io/setvbuf">setvbuf</a></code> indicating unbuffered I/O <br> <span class="t-mark">(macro constant)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><span class="t-lines"><span>SEEK_SET</span><span>SEEK_CUR</span><span>SEEK_END</span></span></div> </td> <td> argument to <code><a href="io/fseek" title="c/io/fseek">fseek</a></code> indicating seeking from beginning of the file<br>argument to <code><a href="io/fseek" title="c/io/fseek">fseek</a></code> indicating seeking from the current file position<br>argument to <code><a href="io/fseek" title="c/io/fseek">fseek</a></code> indicating seeking from end of the file <br> <span class="t-mark">(macro constant)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><span class="t-lines"><span>TMP_MAX</span><span>TMP_MAX_S</span></span></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div> </td> <td> maximum number of unique filenames that can be generated by <code><a href="io/tmpnam" title="c/io/tmpnam">tmpnam</a></code><br>maximum number of unique filenames that can be generated by <code>tmpnam_s</code> <br> <span class="t-mark">(macro constant)</span> </td>
</tr> <tr class="t-dsc"> <td> <div><span class="t-lines"><span>L_tmpnam</span><span>L_tmpnam_s</span></span></div>
<div><span class="t-lines"><span><span class="t-mark-rev t-since-c11">(C11)</span></span></span></div> </td> <td> size needed for an array of <code>char</code> to hold the result of <code><a href="io/tmpnam" title="c/io/tmpnam">tmpnam</a></code><br>size needed for an array of <code>char</code> to hold the result of <code>tmpnam_s</code> <br> <span class="t-mark">(macro constant)</span> </td>
</tr> </table> <h3 id="References"> References</h3> <ul>
<li> C23 standard (ISO/IEC 9899:2023): </li>
<ul>
<li> 7.21 Input/output <stdio.h> (p: TBD) </li>
<li> 7.29 Extended multibyte and wide character utilities <wchar.h> (p: TBD) </li>
<li> 7.31.11 Input/output <stdio.h> (p: TBD) </li>
<li> 7.31.16 Extended multibyte and wide character utilities <wchar.h> (p: TBD) </li>
<li> K.3.5 Input/output <stdio.h> (p: TBD) </li>
</ul>
<li> C17 standard (ISO/IEC 9899:2018): </li>
<ul>
<li> 7.21 Input/output <stdio.h> (p: TBD) </li>
<li> 7.29 Extended multibyte and wide character utilities <wchar.h> (p: TBD) </li>
<li> 7.31.11 Input/output <stdio.h> (p: TBD) </li>
<li> 7.31.16 Extended multibyte and wide character utilities <wchar.h> (p: TBD) </li>
<li> K.3.5 Input/output <stdio.h> (p: TBD) </li>
</ul>
<li> C11 standard (ISO/IEC 9899:2011): </li>
<ul>
<li> 7.21 Input/output <stdio.h> (p: 296-339) </li>
<li> 7.29 Extended multibyte and wide character utilities <wchar.h> (p: 402-446) </li>
<li> 7.31.11 Input/output <stdio.h> (p: 456) </li>
<li> 7.31.16 Extended multibyte and wide character utilities <wchar.h> (p: 456) </li>
<li> K.3.5 Input/output <stdio.h> (p: 586-603) </li>
</ul>
<li> C99 standard (ISO/IEC 9899:1999): </li>
<ul>
<li> 7.19 Input/output <stdio.h> (p: 262-305) </li>
<li> 7.24 Extended multibyte and wide character utilities <wchar.h> (p: 348-392) </li>
<li> 7.26.9 Input/output <stdio.h> (p: 402) </li>
<li> 7.26.12 Extended multibyte and wide character utilities <wchar.h> (p: 402) </li>
</ul>
<li> C89/C90 standard (ISO/IEC 9899:1990): </li>
<ul>
<li> 4.9 INPUT/OUTPUT <stdio.h> </li>
<li> 4.13.6 Input/output <stdio.h> </li>
</ul>
</ul> <h3 id="See_also"> See also</h3> <table class="t-dsc-begin"> <tr class="t-dsc"> <td colspan="2"> <span><a href="https://en.cppreference.com/w/cpp/io/c" title="cpp/io/c">C++ documentation</a></span> for <span class=""><span>C-style file input/output</span></span> </td>
</tr> </table> <div class="_attribution">
<p class="_attribution-p">
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