<!-- Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009, 2013 The President and Fellows of Harvard College. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 3. Neither the name of the University nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. --> <html> <head> <title>printf</title> <body bgcolor=#ffffff> <h2 align=center>printf</h2> <h4 align=center>OS/161 Reference Manual</h4> <h3>Name</h3> <p> printf - print formatted output </p> <h3>Library</h3> <p> Standard C Library (libc, -lc) </p> <h3>Synopsis</h3> <p> <tt>#include <stdio.h></tt><br> <br> <tt>int</tt><br> <tt>printf(const char *</tt><em>format</em><tt>, ...);</tt> </p> <h3>Description</h3> <p> <tt>printf</tt> prints formatted text to standard output. The text is generated from the <em>format</em> argument and subsequent arguments according to the following rules. </p> <p> Characters in <em>format</em> that are not the percent sign (<tt>%</tt>) are printed verbatim. When a percent sign is encountered, the next argument of the arguments following <em>format</em> is retrieved and printed. The type of the argument expected, as well as some simple formatting instructions, are derived from the characters following the percent sign. </p> <p> The following characters designate types to print. One of these characters concludes the format sequence begun with a percent sign, and also determines the type expected as an argument. </p> <table width=90%> <tr><td width=5% rowspan=9> <td width=5%>%</td> <td>A percent sign is printed; no argument is consumed.</td></tr> <tr><td>c</td> <td>Character (char, passed as an integer value)</td></tr> <tr><td>d</td> <td>Signed integer value printed in decimal</td></tr> <tr><td>o</td> <td>Unsigned integer value printed in octal</td></tr> <tr><td>p</td> <td>Pointer (void *)</td></tr> <tr><td>s</td> <td>String (const char *)</td></tr> <tr><td>u</td> <td>Unsigned integer value printed in decimal</td></tr> <tr><td>x</td> <td>Unsigned integer value printed in hexadecimal</td></tr> <tr><td>X</td> <td>Unsigned integer value printed in uppercase hex</td></tr> </table> <p> The following characters are modifiers; they can be found between the percent sign and the type designator. </p> <table width=90%> <tr><td width=5% rowspan=6> <td width=5% valign=top>#</td> <td>Select an "alternate format". On integer formats this causes the C base prefix to be printed along with the integer. On other formats, this has no effect.</td></tr> <tr><td valign=top>l</td> <td>Assume an integer argument is <tt>long</tt> or <tt>unsigned long</tt> instead of <tt>int</tt> or <tt>unsigned int</tt>. If repeated, the argument is taken to be <tt>long long</tt> or <tt>unsigned long long</tt>. </td></tr> <tr><td valign=top>z</td> <td>Assume an integer argument is <tt>ssize_t</tt> or <tt>size_t</tt> instead of <tt>int</tt> or <tt>unsigned int</tt>. </td></tr> <tr><td valign=top>0-9</td> <td>Digits are treated as a decimal number, which is considered to be the field width. The argument is printed right-aligned in a field that many characters wide.</td></tr> <tr><td valign=top>0</td> <td>If the field width has a leading 0, the padding character for alignment is made 0 (zero) instead of space.</td></tr> <tr><td valign=top>-</td> <td>If a field width is given, use it for left alignment instead of right alignment.</td></tr> </table> <h3>Restrictions</h3> <p> Note that this is a limited printf implementation - it has no support for precisions (".number" as a modifier), floating-point formats, field widths passed as arguments, or the rarely-used plus and space modifiers. </p> <h3>Return Values</h3> <p> <tt>printf</tt> returns the number of characters printed. </p> </body> </html>