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POHow to call a template method?
 

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  1. POHow to call a template method?
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    <p>There are a lot of online documents explaining how to write template methods, but not much example about how to call them, how to use them in code.</p> <p>I have a template method like this: <br /><br /> <strong>VectorConvertor.h</strong></p> <pre><code>template &lt;class T&gt; static void AppendToVector(std::vector&lt;T&gt; & VectorToBeAppended, std::vector&lt;T&gt; & VectorToAppend);</code></pre> <p><br /> <strong>VectorConvertor.cpp</strong> <pre><code>template &lt;class T&gt; void VectorConvertor::AppendToVector(std::vector&lt;T&gt; &amp; VectorToBeAppended, std::vector&lt;T&gt; &amp; VectorToAppend) { for (std::vector::size_type i=0; i&lt;VectorToAppend.size(); i++) { VectorToBeAppended.push_back(VectorToAppend.at(i)); } }</code></pre><br /></p> <p><strong>Usage attempt in code:</strong> <pre><code>std::vector&lt;uint8_t&gt; InputData, OutputData; // ... VectorConvertor::AppendToVector(OutputData, InputData);</code></pre><br /><br /></p> <p>I compile this code without any error. But when I try to use this method I get the following errors:</p> <blockquote> <p>error LNK1120: 1 unresolved externals</p> </blockquote> <p>and</p> <blockquote> <p>error LNK2019: unresolved external symbol "public: static void __cdecl VectorConvertor::AppendToVector(class std::vector > &amp;,class std::vector > &amp;)" (??$AppendToVector@E@VectorConvertor@@SAXAEAV?$vector@EV?$allocator@E@std@@@std@@0@Z) referenced in function "public: staticclass std::vector > __cdecl Utf8::WStringToUtf8(class std::basic_string,class std::allocator >)" (?WStringToUtf8@Utf8@@SA?AV?$vector@EV?$allocator@E@std@@@std@@V?$basic_string@_WU?$char_traits@_W@std@@V?$allocator@_W@2@@3@@Z)</p> </blockquote> <p><br /></p> <p>When I don't use this method in my code I don't get any error messages. What am I doing wrong while calling it? Am I missing something?</p> <p><br /></p> <p>I'm using Visual Studio 2010 Express Edition.</p>
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    1. UShkBattousai
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    1. CONot helpful, but these kinds of error messages were just the reason why i stopped coding with C++.
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      1. USJan Thomä
    2. COFor clarity, do not confuse `template method` (which is a design pattern) with `class template member function` and `function template`.
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      1. USSteve Townsend
 

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