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<title>bitflags::__core::ffi::CStr - Rust</title>
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<p class='location'><a href='../../index.html'>bitflags</a>::<wbr><a href='../index.html'>__core</a>::<wbr><a href='index.html'>ffi</a></p><script>window.sidebarCurrent = {name: 'CStr', ty: 'struct', relpath: ''};</script><script defer src="sidebar-items.js"></script>
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<section id='main' class="content struct">
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<h1 class='fqn'><span class='in-band'>Struct <a href='../../index.html'>bitflags</a>::<wbr><a href='../index.html'>__core</a>::<wbr><a href='index.html'>ffi</a>::<wbr><a class='struct' href=''>CStr</a></span><span class='out-of-band'><span id='render-detail'>
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[<span class='inner'>−</span>]
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</span><a id='src-3069' class='srclink' href='https://doc.rust-lang.org/nightly/std/ffi/c_str/struct.CStr.html?gotosrc=3069' title='goto source code'>[src]</a></span></h1>
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<pre class='rust struct'>pub struct CStr {
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// some fields omitted
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}</pre><span class="since">1.0.0</span><div class='docblock'><p>Representation of a borrowed C string.</p>
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<p>This dynamically sized type is only safely constructed via a borrowed
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version of an instance of <code>CString</code>. This type can be constructed from a raw
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C string as well and represents a C string borrowed from another location.</p>
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<p>Note that this structure is <strong>not</strong> <code>repr(C)</code> and is not recommended to be
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placed in the signatures of FFI functions. Instead safe wrappers of FFI
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functions may leverage the unsafe <code>from_ptr</code> constructor to provide a safe
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interface to other consumers.</p>
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<h1 id='examples' class='section-header'><a href='#examples'>Examples</a></h1>
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<p>Inspecting a foreign C string</p>
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<pre class='rust rust-example-rendered'>
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<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>ffi</span>::<span class='ident'>CStr</span>;
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<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>os</span>::<span class='ident'>raw</span>::<span class='ident'>c_char</span>;
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<span class='kw'>extern</span> { <span class='kw'>fn</span> <span class='ident'>my_string</span>() <span class='op'>-></span> <span class='op'>*</span><span class='kw'>const</span> <span class='ident'>c_char</span>; }
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<span class='kw'>fn</span> <span class='ident'>main</span>() {
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<span class='kw'>unsafe</span> {
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<span class='kw'>let</span> <span class='ident'>slice</span> <span class='op'>=</span> <span class='ident'>CStr</span>::<span class='ident'>from_ptr</span>(<span class='ident'>my_string</span>());
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<span class='macro'>println</span><span class='macro'>!</span>(<span class='string'>"string length: {}"</span>, <span class='ident'>slice</span>.<span class='ident'>to_bytes</span>().<span class='ident'>len</span>());
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}
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}</pre>
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<p>Passing a Rust-originating C string</p>
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<pre class='rust rust-example-rendered'>
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<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>ffi</span>::{<span class='ident'>CString</span>, <span class='ident'>CStr</span>};
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<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>os</span>::<span class='ident'>raw</span>::<span class='ident'>c_char</span>;
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<span class='kw'>fn</span> <span class='ident'>work</span>(<span class='ident'>data</span>: <span class='kw-2'>&</span><span class='ident'>CStr</span>) {
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<span class='kw'>extern</span> { <span class='kw'>fn</span> <span class='ident'>work_with</span>(<span class='ident'>data</span>: <span class='op'>*</span><span class='kw'>const</span> <span class='ident'>c_char</span>); }
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<span class='kw'>unsafe</span> { <span class='ident'>work_with</span>(<span class='ident'>data</span>.<span class='ident'>as_ptr</span>()) }
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}
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<span class='kw'>fn</span> <span class='ident'>main</span>() {
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<span class='kw'>let</span> <span class='ident'>s</span> <span class='op'>=</span> <span class='ident'>CString</span>::<span class='ident'>new</span>(<span class='string'>"data data data data"</span>).<span class='ident'>unwrap</span>();
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<span class='ident'>work</span>(<span class='kw-2'>&</span><span class='ident'>s</span>);
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}</pre>
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<p>Converting a foreign C string into a Rust <code>String</code></p>
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<pre class='rust rust-example-rendered'>
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<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>ffi</span>::<span class='ident'>CStr</span>;
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<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>os</span>::<span class='ident'>raw</span>::<span class='ident'>c_char</span>;
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<span class='kw'>extern</span> { <span class='kw'>fn</span> <span class='ident'>my_string</span>() <span class='op'>-></span> <span class='op'>*</span><span class='kw'>const</span> <span class='ident'>c_char</span>; }
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<span class='kw'>fn</span> <span class='ident'>my_string_safe</span>() <span class='op'>-></span> <span class='ident'>String</span> {
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<span class='kw'>unsafe</span> {
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<span class='ident'>CStr</span>::<span class='ident'>from_ptr</span>(<span class='ident'>my_string</span>()).<span class='ident'>to_string_lossy</span>().<span class='ident'>into_owned</span>()
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}
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}
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<span class='kw'>fn</span> <span class='ident'>main</span>() {
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<span class='macro'>println</span><span class='macro'>!</span>(<span class='string'>"string: {}"</span>, <span class='ident'>my_string_safe</span>());
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}</pre>
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