| |
| <!DOCTYPE html> |
| |
| <html lang="en"> |
| <head> |
| <meta charset="utf-8" /> |
| <meta name="viewport" content="width=device-width, initial-scale=1.0" /> |
| <title>if — CMake 3.23.1 Documentation</title> |
| |
| <link rel="stylesheet" type="text/css" href="../_static/pygments.css" /> |
| <link rel="stylesheet" type="text/css" href="../_static/cmake.css" /> |
| |
| <script data-url_root="../" id="documentation_options" src="../_static/documentation_options.js"></script> |
| <script src="../_static/jquery.js"></script> |
| <script src="../_static/underscore.js"></script> |
| <script src="../_static/doctools.js"></script> |
| |
| <link rel="shortcut icon" href="../_static/cmake-favicon.ico"/> |
| <link rel="index" title="Index" href="../genindex.html" /> |
| <link rel="search" title="Search" href="../search.html" /> |
| <link rel="next" title="include" href="include.html" /> |
| <link rel="prev" title="get_property" href="get_property.html" /> |
| |
| |
| </head><body> |
| |
| <div class="related" role="navigation" aria-label="related navigation"> |
| <h3>Navigation</h3> |
| <ul> |
| <li class="right" style="margin-right: 10px"> |
| <a href="../genindex.html" title="General Index" |
| accesskey="I">index</a></li> |
| <li class="right" > |
| <a href="include.html" title="include" |
| accesskey="N">next</a> |</li> |
| <li class="right" > |
| <a href="get_property.html" title="get_property" |
| accesskey="P">previous</a> |</li> |
| <li> |
| <img src="../_static/cmake-logo-16.png" alt="" |
| style="vertical-align: middle; margin-top: -2px" /> |
| </li> |
| <li> |
| <a href="https://cmake.org/">CMake</a> » |
| </li> |
| <li> |
| <a href="../index.html">3.23.1 Documentation</a> » |
| </li> |
| |
| <li class="nav-item nav-item-1"><a href="../manual/cmake-commands.7.html" accesskey="U">cmake-commands(7)</a> »</li> |
| <li class="nav-item nav-item-this"><a href="">if</a></li> |
| </ul> |
| </div> |
| |
| <div class="document"> |
| <div class="documentwrapper"> |
| <div class="bodywrapper"> |
| <div class="body" role="main"> |
| |
| <div class="section" id="if"> |
| <span id="command:if"></span><h1>if<a class="headerlink" href="#if" title="Permalink to this headline">¶</a></h1> |
| <p>Conditionally execute a group of commands.</p> |
| <div class="section" id="synopsis"> |
| <h2>Synopsis<a class="headerlink" href="#synopsis" title="Permalink to this headline">¶</a></h2> |
| <div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">if(</span><span class="nv"><condition></span><span class="nf">)</span><span class="w"></span> |
| <span class="w"> </span><span class="nv"><commands></span><span class="w"></span> |
| <span class="nf">elseif(</span><span class="nv"><condition></span><span class="nf">)</span><span class="w"> </span><span class="c"># optional block, can be repeated</span> |
| <span class="w"> </span><span class="nv"><commands></span><span class="w"></span> |
| <span class="nf">else()</span><span class="w"> </span><span class="c"># optional block</span> |
| <span class="w"> </span><span class="nv"><commands></span><span class="w"></span> |
| <span class="nf">endif()</span><span class="w"></span> |
| </pre></div> |
| </div> |
| <p>Evaluates the <code class="docutils literal notranslate"><span class="pre">condition</span></code> argument of the <code class="docutils literal notranslate"><span class="pre">if</span></code> clause according to the |
| <a class="reference internal" href="#condition-syntax">Condition syntax</a> described below. If the result is true, then the |
| <code class="docutils literal notranslate"><span class="pre">commands</span></code> in the <code class="docutils literal notranslate"><span class="pre">if</span></code> block are executed. |
| Otherwise, optional <code class="docutils literal notranslate"><span class="pre">elseif</span></code> blocks are processed in the same way. |
| Finally, if no <code class="docutils literal notranslate"><span class="pre">condition</span></code> is true, <code class="docutils literal notranslate"><span class="pre">commands</span></code> in the optional <code class="docutils literal notranslate"><span class="pre">else</span></code> |
| block are executed.</p> |
| <p>Per legacy, the <span class="target" id="index-0-command:else"></span><a class="reference internal" href="else.html#command:else" title="else"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">else()</span></code></a> and <span class="target" id="index-0-command:endif"></span><a class="reference internal" href="endif.html#command:endif" title="endif"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">endif()</span></code></a> commands admit |
| an optional <code class="docutils literal notranslate"><span class="pre"><condition></span></code> argument. |
| If used, it must be a verbatim |
| repeat of the argument of the opening |
| <code class="docutils literal notranslate"><span class="pre">if</span></code> command.</p> |
| </div> |
| <div class="section" id="condition-syntax"> |
| <span id="id1"></span><h2>Condition Syntax<a class="headerlink" href="#condition-syntax" title="Permalink to this headline">¶</a></h2> |
| <p>The following syntax applies to the <code class="docutils literal notranslate"><span class="pre">condition</span></code> argument of |
| the <code class="docutils literal notranslate"><span class="pre">if</span></code>, <code class="docutils literal notranslate"><span class="pre">elseif</span></code> and <span class="target" id="index-0-command:while"></span><a class="reference internal" href="while.html#command:while" title="while"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">while()</span></code></a> clauses.</p> |
| <p>Compound conditions are evaluated in the following order of precedence:</p> |
| <ol class="arabic simple"> |
| <li><p>Parentheses.</p></li> |
| <li><p>Unary tests such as <a class="reference internal" href="#exists">EXISTS</a>, <a class="reference internal" href="#command">COMMAND</a>, and <a class="reference internal" href="#defined">DEFINED</a>.</p></li> |
| <li><p>Binary tests such as <a class="reference internal" href="#equal">EQUAL</a>, <a class="reference internal" href="#less">LESS</a>, <a class="reference internal" href="#less-equal">LESS_EQUAL</a>, <a class="reference internal" href="#greater">GREATER</a>, |
| <a class="reference internal" href="#greater-equal">GREATER_EQUAL</a>, <a class="reference internal" href="#strequal">STREQUAL</a>, <a class="reference internal" href="#strless">STRLESS</a>, <a class="reference internal" href="#strless-equal">STRLESS_EQUAL</a>, |
| <a class="reference internal" href="#strgreater">STRGREATER</a>, <a class="reference internal" href="#strgreater-equal">STRGREATER_EQUAL</a>, <a class="reference internal" href="#version-equal">VERSION_EQUAL</a>, <a class="reference internal" href="#version-less">VERSION_LESS</a>, |
| <a class="reference internal" href="#version-less-equal">VERSION_LESS_EQUAL</a>, <a class="reference internal" href="#version-greater">VERSION_GREATER</a>, <a class="reference internal" href="#version-greater-equal">VERSION_GREATER_EQUAL</a>, |
| and <a class="reference internal" href="#matches">MATCHES</a>.</p></li> |
| <li><p>Unary logical operator <a class="reference internal" href="#not">NOT</a>.</p></li> |
| <li><p>Binary logical operators <a class="reference internal" href="#and">AND</a> and <a class="reference internal" href="#or">OR</a>, from left to right, |
| without any short-circuit.</p></li> |
| </ol> |
| <div class="section" id="basic-expressions"> |
| <h3>Basic Expressions<a class="headerlink" href="#basic-expressions" title="Permalink to this headline">¶</a></h3> |
| <dl class="simple"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(<constant>)</span></code></dt><dd><p>True if the constant is <code class="docutils literal notranslate"><span class="pre">1</span></code>, <code class="docutils literal notranslate"><span class="pre">ON</span></code>, <code class="docutils literal notranslate"><span class="pre">YES</span></code>, <code class="docutils literal notranslate"><span class="pre">TRUE</span></code>, <code class="docutils literal notranslate"><span class="pre">Y</span></code>, |
| or a non-zero number (including floating point numbers). |
| False if the constant is <code class="docutils literal notranslate"><span class="pre">0</span></code>, <code class="docutils literal notranslate"><span class="pre">OFF</span></code>, |
| <code class="docutils literal notranslate"><span class="pre">NO</span></code>, <code class="docutils literal notranslate"><span class="pre">FALSE</span></code>, <code class="docutils literal notranslate"><span class="pre">N</span></code>, <code class="docutils literal notranslate"><span class="pre">IGNORE</span></code>, <code class="docutils literal notranslate"><span class="pre">NOTFOUND</span></code>, the empty string, |
| or ends in the suffix <code class="docutils literal notranslate"><span class="pre">-NOTFOUND</span></code>. Named boolean constants are |
| case-insensitive. If the argument is not one of these specific |
| constants, it is treated as a variable or string (see <a class="reference internal" href="#variable-expansion">Variable Expansion</a> |
| further below) and one of the following two forms applies.</p> |
| </dd> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(<variable>)</span></code></dt><dd><p>True if given a variable that is defined to a value that is not a false |
| constant. False otherwise, including if the variable is undefined. |
| Note that macro arguments are not variables. |
| Environment variables also cannot be tested this way, e.g. |
| <code class="docutils literal notranslate"><span class="pre">if(ENV{some_var})</span></code> will always evaluate to false.</p> |
| </dd> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(<string>)</span></code></dt><dd><p>A quoted string always evaluates to false unless:</p> |
| <ul class="simple"> |
| <li><p>The string's value is one of the true constants, or</p></li> |
| <li><p>Policy <span class="target" id="index-0-policy:CMP0054"></span><a class="reference internal" href="../policy/CMP0054.html#policy:CMP0054" title="CMP0054"><code class="xref cmake cmake-policy docutils literal notranslate"><span class="pre">CMP0054</span></code></a> is not set to <code class="docutils literal notranslate"><span class="pre">NEW</span></code> and the string's value |
| happens to be a variable name that is affected by <span class="target" id="index-1-policy:CMP0054"></span><a class="reference internal" href="../policy/CMP0054.html#policy:CMP0054" title="CMP0054"><code class="xref cmake cmake-policy docutils literal notranslate"><span class="pre">CMP0054</span></code></a>'s |
| behavior.</p></li> |
| </ul> |
| </dd> |
| </dl> |
| </div> |
| <div class="section" id="logic-operators"> |
| <h3>Logic Operators<a class="headerlink" href="#logic-operators" title="Permalink to this headline">¶</a></h3> |
| <dl class="simple" id="not"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(NOT</span> <span class="pre"><condition>)</span></code></dt><dd><p>True if the condition is not true.</p> |
| </dd> |
| </dl> |
| <dl class="simple" id="and"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(<cond1></span> <span class="pre">AND</span> <span class="pre"><cond2>)</span></code></dt><dd><p>True if both conditions would be considered true individually.</p> |
| </dd> |
| </dl> |
| <dl class="simple" id="or"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(<cond1></span> <span class="pre">OR</span> <span class="pre"><cond2>)</span></code></dt><dd><p>True if either condition would be considered true individually.</p> |
| </dd> |
| <dt><code class="docutils literal notranslate"><span class="pre">if((condition)</span> <span class="pre">AND</span> <span class="pre">(condition</span> <span class="pre">OR</span> <span class="pre">(condition)))</span></code></dt><dd><p>The conditions inside the parenthesis are evaluated first and then |
| the remaining condition is evaluated as in the other examples. |
| Where there are nested parenthesis the innermost are evaluated as part |
| of evaluating the condition that contains them.</p> |
| </dd> |
| </dl> |
| </div> |
| <div class="section" id="existence-checks"> |
| <h3>Existence Checks<a class="headerlink" href="#existence-checks" title="Permalink to this headline">¶</a></h3> |
| <dl id="command"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(COMMAND</span> <span class="pre">command-name)</span></code></dt><dd><p>True if the given name is a command, macro or function that can be |
| invoked.</p> |
| </dd> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(POLICY</span> <span class="pre">policy-id)</span></code></dt><dd><p>True if the given name is an existing policy (of the form <code class="docutils literal notranslate"><span class="pre">CMP<NNNN></span></code>).</p> |
| </dd> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(TARGET</span> <span class="pre">target-name)</span></code></dt><dd><p>True if the given name is an existing logical target name created |
| by a call to the <span class="target" id="index-0-command:add_executable"></span><a class="reference internal" href="add_executable.html#command:add_executable" title="add_executable"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">add_executable()</span></code></a>, <span class="target" id="index-0-command:add_library"></span><a class="reference internal" href="add_library.html#command:add_library" title="add_library"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">add_library()</span></code></a>, |
| or <span class="target" id="index-0-command:add_custom_target"></span><a class="reference internal" href="add_custom_target.html#command:add_custom_target" title="add_custom_target"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">add_custom_target()</span></code></a> command that has already been invoked |
| (in any directory).</p> |
| </dd> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(TEST</span> <span class="pre">test-name)</span></code></dt><dd><div class="versionadded"> |
| <p><span class="versionmodified added">New in version 3.3: </span>True if the given name is an existing test name created by the |
| <span class="target" id="index-0-command:add_test"></span><a class="reference internal" href="add_test.html#command:add_test" title="add_test"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">add_test()</span></code></a> command.</p> |
| </div> |
| </dd> |
| </dl> |
| <dl id="defined"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(DEFINED</span> <span class="pre"><name>|CACHE{<name>}|ENV{<name>})</span></code></dt><dd><p>True if a variable, cache variable or environment variable |
| with given <code class="docutils literal notranslate"><span class="pre"><name></span></code> is defined. The value of the variable |
| does not matter. Note the following caveats:</p> |
| <ul class="simple"> |
| <li><p>Macro arguments are not variables.</p></li> |
| <li><p>It is not possible to test directly whether a <cite><name></cite> is a non-cache |
| variable. The expression <code class="docutils literal notranslate"><span class="pre">if(DEFINED</span> <span class="pre">someName)</span></code> will evaluate to true |
| if either a cache or non-cache variable <code class="docutils literal notranslate"><span class="pre">someName</span></code> exists. In |
| comparison, the expression <code class="docutils literal notranslate"><span class="pre">if(DEFINED</span> <span class="pre">CACHE{someName})</span></code> will only |
| evaluate to true if a cache variable <code class="docutils literal notranslate"><span class="pre">someName</span></code> exists. Both expressions |
| need to be tested if you need to know whether a non-cache variable exists: |
| <code class="docutils literal notranslate"><span class="pre">if(DEFINED</span> <span class="pre">someName</span> <span class="pre">AND</span> <span class="pre">NOT</span> <span class="pre">DEFINED</span> <span class="pre">CACHE{someName})</span></code>.</p></li> |
| </ul> |
| <div class="versionadded"> |
| <p><span class="versionmodified added">New in version 3.14: </span>Added support for <code class="docutils literal notranslate"><span class="pre">CACHE{<name>}</span></code> variables.</p> |
| </div> |
| </dd> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(<variable|string></span> <span class="pre">IN_LIST</span> <span class="pre"><variable>)</span></code></dt><dd><div class="versionadded"> |
| <p><span class="versionmodified added">New in version 3.3: </span>True if the given element is contained in the named list variable.</p> |
| </div> |
| </dd> |
| </dl> |
| </div> |
| <div class="section" id="file-operations"> |
| <h3>File Operations<a class="headerlink" href="#file-operations" title="Permalink to this headline">¶</a></h3> |
| <dl class="simple" id="exists"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(EXISTS</span> <span class="pre">path-to-file-or-directory)</span></code></dt><dd><p>True if the named file or directory exists. Behavior is well-defined |
| only for explicit full paths (a leading <code class="docutils literal notranslate"><span class="pre">~/</span></code> is not expanded as |
| a home directory and is considered a relative path). |
| Resolves symbolic links, i.e. if the named file or directory is a |
| symbolic link, returns true if the target of the symbolic link exists.</p> |
| </dd> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(file1</span> <span class="pre">IS_NEWER_THAN</span> <span class="pre">file2)</span></code></dt><dd><p>True if <code class="docutils literal notranslate"><span class="pre">file1</span></code> is newer than <code class="docutils literal notranslate"><span class="pre">file2</span></code> or if one of the two files doesn't |
| exist. Behavior is well-defined only for full paths. If the file |
| time stamps are exactly the same, an <code class="docutils literal notranslate"><span class="pre">IS_NEWER_THAN</span></code> comparison returns |
| true, so that any dependent build operations will occur in the event |
| of a tie. This includes the case of passing the same file name for |
| both file1 and file2.</p> |
| </dd> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(IS_DIRECTORY</span> <span class="pre">path-to-directory)</span></code></dt><dd><p>True if the given name is a directory. Behavior is well-defined only |
| for full paths.</p> |
| </dd> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(IS_SYMLINK</span> <span class="pre">file-name)</span></code></dt><dd><p>True if the given name is a symbolic link. Behavior is well-defined |
| only for full paths.</p> |
| </dd> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(IS_ABSOLUTE</span> <span class="pre">path)</span></code></dt><dd><p>True if the given path is an absolute path. Note the following special |
| cases:</p> |
| <ul class="simple"> |
| <li><p>An empty <code class="docutils literal notranslate"><span class="pre">path</span></code> evaluates to false.</p></li> |
| <li><p>On Windows hosts, any <code class="docutils literal notranslate"><span class="pre">path</span></code> that begins with a drive letter and colon |
| (e.g. <code class="docutils literal notranslate"><span class="pre">C:</span></code>), a forward slash or a backslash will evaluate to true. |
| This means a path like <code class="docutils literal notranslate"><span class="pre">C:no\base\dir</span></code> will evaluate to true, even |
| though the non-drive part of the path is relative.</p></li> |
| <li><p>On non-Windows hosts, any <code class="docutils literal notranslate"><span class="pre">path</span></code> that begins with a tilde (<code class="docutils literal notranslate"><span class="pre">~</span></code>) |
| evaluates to true.</p></li> |
| </ul> |
| </dd> |
| </dl> |
| </div> |
| <div class="section" id="comparisons"> |
| <h3>Comparisons<a class="headerlink" href="#comparisons" title="Permalink to this headline">¶</a></h3> |
| <dl id="matches"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(<variable|string></span> <span class="pre">MATCHES</span> <span class="pre">regex)</span></code></dt><dd><p>True if the given string or variable's value matches the given regular |
| expression. See <a class="reference internal" href="string.html#regex-specification"><span class="std std-ref">Regex Specification</span></a> for regex format.</p> |
| <div class="versionadded"> |
| <p><span class="versionmodified added">New in version 3.9: </span><code class="docutils literal notranslate"><span class="pre">()</span></code> groups are captured in <span class="target" id="index-0-variable:CMAKE_MATCH_<n>"></span><a class="reference internal" href="../variable/CMAKE_MATCH_n.html#variable:CMAKE_MATCH_<n>" title="CMAKE_MATCH_<n>"><code class="xref cmake cmake-variable docutils literal notranslate"><span class="pre">CMAKE_MATCH_<n></span></code></a> variables.</p> |
| </div> |
| </dd> |
| </dl> |
| <dl class="simple" id="less"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(<variable|string></span> <span class="pre">LESS</span> <span class="pre"><variable|string>)</span></code></dt><dd><p>True if the given string or variable's value is a valid number and less |
| than that on the right.</p> |
| </dd> |
| </dl> |
| <dl class="simple" id="greater"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(<variable|string></span> <span class="pre">GREATER</span> <span class="pre"><variable|string>)</span></code></dt><dd><p>True if the given string or variable's value is a valid number and greater |
| than that on the right.</p> |
| </dd> |
| </dl> |
| <dl class="simple" id="equal"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(<variable|string></span> <span class="pre">EQUAL</span> <span class="pre"><variable|string>)</span></code></dt><dd><p>True if the given string or variable's value is a valid number and equal |
| to that on the right.</p> |
| </dd> |
| </dl> |
| <dl id="less-equal"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(<variable|string></span> <span class="pre">LESS_EQUAL</span> <span class="pre"><variable|string>)</span></code></dt><dd><div class="versionadded"> |
| <p><span class="versionmodified added">New in version 3.7: </span>True if the given string or variable's value is a valid number and less |
| than or equal to that on the right.</p> |
| </div> |
| </dd> |
| </dl> |
| <dl id="greater-equal"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(<variable|string></span> <span class="pre">GREATER_EQUAL</span> <span class="pre"><variable|string>)</span></code></dt><dd><div class="versionadded"> |
| <p><span class="versionmodified added">New in version 3.7: </span>True if the given string or variable's value is a valid number and greater |
| than or equal to that on the right.</p> |
| </div> |
| </dd> |
| </dl> |
| <dl class="simple" id="strless"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(<variable|string></span> <span class="pre">STRLESS</span> <span class="pre"><variable|string>)</span></code></dt><dd><p>True if the given string or variable's value is lexicographically less |
| than the string or variable on the right.</p> |
| </dd> |
| </dl> |
| <dl class="simple" id="strgreater"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(<variable|string></span> <span class="pre">STRGREATER</span> <span class="pre"><variable|string>)</span></code></dt><dd><p>True if the given string or variable's value is lexicographically greater |
| than the string or variable on the right.</p> |
| </dd> |
| </dl> |
| <dl class="simple" id="strequal"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(<variable|string></span> <span class="pre">STREQUAL</span> <span class="pre"><variable|string>)</span></code></dt><dd><p>True if the given string or variable's value is lexicographically equal |
| to the string or variable on the right.</p> |
| </dd> |
| </dl> |
| <dl id="strless-equal"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(<variable|string></span> <span class="pre">STRLESS_EQUAL</span> <span class="pre"><variable|string>)</span></code></dt><dd><div class="versionadded"> |
| <p><span class="versionmodified added">New in version 3.7: </span>True if the given string or variable's value is lexicographically less |
| than or equal to the string or variable on the right.</p> |
| </div> |
| </dd> |
| </dl> |
| <dl id="strgreater-equal"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(<variable|string></span> <span class="pre">STRGREATER_EQUAL</span> <span class="pre"><variable|string>)</span></code></dt><dd><div class="versionadded"> |
| <p><span class="versionmodified added">New in version 3.7: </span>True if the given string or variable's value is lexicographically greater |
| than or equal to the string or variable on the right.</p> |
| </div> |
| </dd> |
| </dl> |
| </div> |
| <div class="section" id="version-comparisons"> |
| <h3>Version Comparisons<a class="headerlink" href="#version-comparisons" title="Permalink to this headline">¶</a></h3> |
| <dl class="simple" id="version-less"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(<variable|string></span> <span class="pre">VERSION_LESS</span> <span class="pre"><variable|string>)</span></code></dt><dd><p>Component-wise integer version number comparison (version format is |
| <code class="docutils literal notranslate"><span class="pre">major[.minor[.patch[.tweak]]]</span></code>, omitted components are treated as zero). |
| Any non-integer version component or non-integer trailing part of a version |
| component effectively truncates the string at that point.</p> |
| </dd> |
| </dl> |
| <dl class="simple" id="version-greater"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(<variable|string></span> <span class="pre">VERSION_GREATER</span> <span class="pre"><variable|string>)</span></code></dt><dd><p>Component-wise integer version number comparison (version format is |
| <code class="docutils literal notranslate"><span class="pre">major[.minor[.patch[.tweak]]]</span></code>, omitted components are treated as zero). |
| Any non-integer version component or non-integer trailing part of a version |
| component effectively truncates the string at that point.</p> |
| </dd> |
| </dl> |
| <dl class="simple" id="version-equal"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(<variable|string></span> <span class="pre">VERSION_EQUAL</span> <span class="pre"><variable|string>)</span></code></dt><dd><p>Component-wise integer version number comparison (version format is |
| <code class="docutils literal notranslate"><span class="pre">major[.minor[.patch[.tweak]]]</span></code>, omitted components are treated as zero). |
| Any non-integer version component or non-integer trailing part of a version |
| component effectively truncates the string at that point.</p> |
| </dd> |
| </dl> |
| <dl id="version-less-equal"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(<variable|string></span> <span class="pre">VERSION_LESS_EQUAL</span> <span class="pre"><variable|string>)</span></code></dt><dd><div class="versionadded"> |
| <p><span class="versionmodified added">New in version 3.7: </span>Component-wise integer version number comparison (version format is |
| <code class="docutils literal notranslate"><span class="pre">major[.minor[.patch[.tweak]]]</span></code>, omitted components are treated as zero). |
| Any non-integer version component or non-integer trailing part of a version |
| component effectively truncates the string at that point.</p> |
| </div> |
| </dd> |
| </dl> |
| <dl id="version-greater-equal"> |
| <dt><code class="docutils literal notranslate"><span class="pre">if(<variable|string></span> <span class="pre">VERSION_GREATER_EQUAL</span> <span class="pre"><variable|string>)</span></code></dt><dd><div class="versionadded"> |
| <p><span class="versionmodified added">New in version 3.7: </span>Component-wise integer version number comparison (version format is |
| <code class="docutils literal notranslate"><span class="pre">major[.minor[.patch[.tweak]]]</span></code>, omitted components are treated as zero). |
| Any non-integer version component or non-integer trailing part of a version |
| component effectively truncates the string at that point.</p> |
| </div> |
| </dd> |
| </dl> |
| </div> |
| </div> |
| <div class="section" id="variable-expansion"> |
| <h2>Variable Expansion<a class="headerlink" href="#variable-expansion" title="Permalink to this headline">¶</a></h2> |
| <p>The if command was written very early in CMake's history, predating |
| the <code class="docutils literal notranslate"><span class="pre">${}</span></code> variable evaluation syntax, and for convenience evaluates |
| variables named by its arguments as shown in the above signatures. |
| Note that normal variable evaluation with <code class="docutils literal notranslate"><span class="pre">${}</span></code> applies before the if |
| command even receives the arguments. Therefore code like</p> |
| <div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">set(</span><span class="nb">var1</span><span class="w"> </span><span class="no">OFF</span><span class="nf">)</span><span class="w"></span> |
| <span class="nf">set(</span><span class="nb">var2</span><span class="w"> </span><span class="s">"var1"</span><span class="nf">)</span><span class="w"></span> |
| <span class="nf">if(</span><span class="o">${</span><span class="nt">var2</span><span class="o">}</span><span class="nf">)</span><span class="w"></span> |
| </pre></div> |
| </div> |
| <p>appears to the if command as</p> |
| <div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">if(</span><span class="nb">var1</span><span class="nf">)</span><span class="w"></span> |
| </pre></div> |
| </div> |
| <p>and is evaluated according to the <code class="docutils literal notranslate"><span class="pre">if(<variable>)</span></code> case documented |
| above. The result is <code class="docutils literal notranslate"><span class="pre">OFF</span></code> which is false. However, if we remove the |
| <code class="docutils literal notranslate"><span class="pre">${}</span></code> from the example then the command sees</p> |
| <div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">if(</span><span class="nb">var2</span><span class="nf">)</span><span class="w"></span> |
| </pre></div> |
| </div> |
| <p>which is true because <code class="docutils literal notranslate"><span class="pre">var2</span></code> is defined to <code class="docutils literal notranslate"><span class="pre">var1</span></code> which is not a false |
| constant.</p> |
| <p>Automatic evaluation applies in the other cases whenever the |
| above-documented condition syntax accepts <code class="docutils literal notranslate"><span class="pre"><variable|string></span></code>:</p> |
| <ul class="simple"> |
| <li><p>The left hand argument to <code class="docutils literal notranslate"><span class="pre">MATCHES</span></code> is first checked to see if it is |
| a defined variable, if so the variable's value is used, otherwise the |
| original value is used.</p></li> |
| <li><p>If the left hand argument to <code class="docutils literal notranslate"><span class="pre">MATCHES</span></code> is missing it returns false |
| without error</p></li> |
| <li><p>Both left and right hand arguments to <code class="docutils literal notranslate"><span class="pre">LESS</span></code>, <code class="docutils literal notranslate"><span class="pre">GREATER</span></code>, <code class="docutils literal notranslate"><span class="pre">EQUAL</span></code>, |
| <code class="docutils literal notranslate"><span class="pre">LESS_EQUAL</span></code>, and <code class="docutils literal notranslate"><span class="pre">GREATER_EQUAL</span></code>, are independently tested to see if |
| they are defined variables, if so their defined values are used otherwise |
| the original value is used.</p></li> |
| <li><p>Both left and right hand arguments to <code class="docutils literal notranslate"><span class="pre">STRLESS</span></code>, <code class="docutils literal notranslate"><span class="pre">STRGREATER</span></code>, |
| <code class="docutils literal notranslate"><span class="pre">STREQUAL</span></code>, <code class="docutils literal notranslate"><span class="pre">STRLESS_EQUAL</span></code>, and <code class="docutils literal notranslate"><span class="pre">STRGREATER_EQUAL</span></code> are independently |
| tested to see if they are defined variables, if so their defined values are |
| used otherwise the original value is used.</p></li> |
| <li><p>Both left and right hand arguments to <code class="docutils literal notranslate"><span class="pre">VERSION_LESS</span></code>, |
| <code class="docutils literal notranslate"><span class="pre">VERSION_GREATER</span></code>, <code class="docutils literal notranslate"><span class="pre">VERSION_EQUAL</span></code>, <code class="docutils literal notranslate"><span class="pre">VERSION_LESS_EQUAL</span></code>, and |
| <code class="docutils literal notranslate"><span class="pre">VERSION_GREATER_EQUAL</span></code> are independently tested to see if they are defined |
| variables, if so their defined values are used otherwise the original value |
| is used.</p></li> |
| <li><p>The right hand argument to <code class="docutils literal notranslate"><span class="pre">NOT</span></code> is tested to see if it is a boolean |
| constant, if so the value is used, otherwise it is assumed to be a |
| variable and it is dereferenced.</p></li> |
| <li><p>The left and right hand arguments to <code class="docutils literal notranslate"><span class="pre">AND</span></code> and <code class="docutils literal notranslate"><span class="pre">OR</span></code> are independently |
| tested to see if they are boolean constants, if so they are used as |
| such, otherwise they are assumed to be variables and are dereferenced.</p></li> |
| </ul> |
| <div class="versionchanged"> |
| <p><span class="versionmodified changed">Changed in version 3.1: </span>To prevent ambiguity, potential variable or keyword names can be |
| specified in a <a class="reference internal" href="../manual/cmake-language.7.html#quoted-argument"><span class="std std-ref">Quoted Argument</span></a> or a <a class="reference internal" href="../manual/cmake-language.7.html#bracket-argument"><span class="std std-ref">Bracket Argument</span></a>. |
| A quoted or bracketed variable or keyword will be interpreted as a |
| string and not dereferenced or interpreted. |
| See policy <span class="target" id="index-2-policy:CMP0054"></span><a class="reference internal" href="../policy/CMP0054.html#policy:CMP0054" title="CMP0054"><code class="xref cmake cmake-policy docutils literal notranslate"><span class="pre">CMP0054</span></code></a>.</p> |
| </div> |
| <p>There is no automatic evaluation for environment or cache |
| <a class="reference internal" href="../manual/cmake-language.7.html#variable-references"><span class="std std-ref">Variable References</span></a>. Their values must be referenced as |
| <code class="docutils literal notranslate"><span class="pre">$ENV{<name>}</span></code> or <code class="docutils literal notranslate"><span class="pre">$CACHE{<name>}</span></code> wherever the above-documented |
| condition syntax accepts <code class="docutils literal notranslate"><span class="pre"><variable|string></span></code>.</p> |
| </div> |
| </div> |
| |
| |
| <div class="clearer"></div> |
| </div> |
| </div> |
| </div> |
| <div class="sphinxsidebar" role="navigation" aria-label="main navigation"> |
| <div class="sphinxsidebarwrapper"> |
| <h3><a href="../index.html">Table of Contents</a></h3> |
| <ul> |
| <li><a class="reference internal" href="#">if</a><ul> |
| <li><a class="reference internal" href="#synopsis">Synopsis</a></li> |
| <li><a class="reference internal" href="#condition-syntax">Condition Syntax</a><ul> |
| <li><a class="reference internal" href="#basic-expressions">Basic Expressions</a></li> |
| <li><a class="reference internal" href="#logic-operators">Logic Operators</a></li> |
| <li><a class="reference internal" href="#existence-checks">Existence Checks</a></li> |
| <li><a class="reference internal" href="#file-operations">File Operations</a></li> |
| <li><a class="reference internal" href="#comparisons">Comparisons</a></li> |
| <li><a class="reference internal" href="#version-comparisons">Version Comparisons</a></li> |
| </ul> |
| </li> |
| <li><a class="reference internal" href="#variable-expansion">Variable Expansion</a></li> |
| </ul> |
| </li> |
| </ul> |
| |
| <h4>Previous topic</h4> |
| <p class="topless"><a href="get_property.html" |
| title="previous chapter">get_property</a></p> |
| <h4>Next topic</h4> |
| <p class="topless"><a href="include.html" |
| title="next chapter">include</a></p> |
| <div role="note" aria-label="source link"> |
| <h3>This Page</h3> |
| <ul class="this-page-menu"> |
| <li><a href="../_sources/command/if.rst.txt" |
| rel="nofollow">Show Source</a></li> |
| </ul> |
| </div> |
| <div id="searchbox" style="display: none" role="search"> |
| <h3 id="searchlabel">Quick search</h3> |
| <div class="searchformwrapper"> |
| <form class="search" action="../search.html" method="get"> |
| <input type="text" name="q" aria-labelledby="searchlabel" autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false"/> |
| <input type="submit" value="Go" /> |
| </form> |
| </div> |
| </div> |
| <script>$('#searchbox').show(0);</script> |
| </div> |
| </div> |
| <div class="clearer"></div> |
| </div> |
| <div class="related" role="navigation" aria-label="related navigation"> |
| <h3>Navigation</h3> |
| <ul> |
| <li class="right" style="margin-right: 10px"> |
| <a href="../genindex.html" title="General Index" |
| >index</a></li> |
| <li class="right" > |
| <a href="include.html" title="include" |
| >next</a> |</li> |
| <li class="right" > |
| <a href="get_property.html" title="get_property" |
| >previous</a> |</li> |
| <li> |
| <img src="../_static/cmake-logo-16.png" alt="" |
| style="vertical-align: middle; margin-top: -2px" /> |
| </li> |
| <li> |
| <a href="https://cmake.org/">CMake</a> » |
| </li> |
| <li> |
| <a href="../index.html">3.23.1 Documentation</a> » |
| </li> |
| |
| <li class="nav-item nav-item-1"><a href="../manual/cmake-commands.7.html" >cmake-commands(7)</a> »</li> |
| <li class="nav-item nav-item-this"><a href="">if</a></li> |
| </ul> |
| </div> |
| |
| <div class="footer" role="contentinfo"> |
| © Copyright 2000-2022 Kitware, Inc. and Contributors. |
| Created using <a href="https://www.sphinx-doc.org/">Sphinx</a> 4.1.2. |
| </div> |
| </body> |
| </html> |
