<html lang="en"> <head> <title>Implicitly convert LOGICAL and INTEGER values - The GNU Fortran Compiler</title> <meta http-equiv="Content-Type" content="text/html"> <meta name="description" content="The GNU Fortran Compiler"> <meta name="generator" content="makeinfo 4.13"> <link title="Top" rel="start" href="index.html#Top"> <link rel="up" href="Extensions-implemented-in-GNU-Fortran.html#Extensions-implemented-in-GNU-Fortran" title="Extensions implemented in GNU Fortran"> <link rel="prev" href="Unary-operators.html#Unary-operators" title="Unary operators"> <link rel="next" href="Hollerith-constants-support.html#Hollerith-constants-support" title="Hollerith constants support"> <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> <!-- Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with the Invariant Sections being ``Funding Free Software'', the Front-Cover Texts being (a) (see below), and with the Back-Cover Texts being (b) (see below). A copy of the license is included in the section entitled ``GNU Free Documentation License''. (a) The FSF's Front-Cover Text is: A GNU Manual (b) The FSF's Back-Cover Text is: You have freedom to copy and modify this GNU Manual, like GNU software. Copies published by the Free Software Foundation raise funds for GNU development.--> <meta http-equiv="Content-Style-Type" content="text/css"> <style type="text/css"><!-- pre.display { font-family:inherit } pre.format { font-family:inherit } pre.smalldisplay { font-family:inherit; font-size:smaller } pre.smallformat { font-family:inherit; font-size:smaller } pre.smallexample { font-size:smaller } pre.smalllisp { font-size:smaller } span.sc { font-variant:small-caps } span.roman { font-family:serif; font-weight:normal; } span.sansserif { font-family:sans-serif; font-weight:normal; } --></style> </head> <body> <div class="node"> <a name="Implicitly-convert-LOGICAL-and-INTEGER-values"></a> <p> Next: <a rel="next" accesskey="n" href="Hollerith-constants-support.html#Hollerith-constants-support">Hollerith constants support</a>, Previous: <a rel="previous" accesskey="p" href="Unary-operators.html#Unary-operators">Unary operators</a>, Up: <a rel="up" accesskey="u" href="Extensions-implemented-in-GNU-Fortran.html#Extensions-implemented-in-GNU-Fortran">Extensions implemented in GNU Fortran</a> <hr> </div> <h4 class="subsection">6.1.12 Implicitly convert <code>LOGICAL</code> and <code>INTEGER</code> values</h4> <p><a name="index-conversion_002c-to-integer-314"></a><a name="index-conversion_002c-to-logical-315"></a> As an extension for backwards compatibility with other compilers, GNU Fortran allows the implicit conversion of <code>LOGICAL</code> values to <code>INTEGER</code> values and vice versa. When converting from a <code>LOGICAL</code> to an <code>INTEGER</code>, <code>.FALSE.</code> is interpreted as zero, and <code>.TRUE.</code> is interpreted as one. When converting from <code>INTEGER</code> to <code>LOGICAL</code>, the value zero is interpreted as <code>.FALSE.</code> and any nonzero value is interpreted as <code>.TRUE.</code>. <pre class="smallexample"> LOGICAL :: l l = 1 </pre> <pre class="smallexample"> INTEGER :: i i = .TRUE. </pre> <p>However, there is no implicit conversion of <code>INTEGER</code> values in <code>if</code>-statements, nor of <code>LOGICAL</code> or <code>INTEGER</code> values in I/O operations. </body></html>