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POWhat does 'Error LNK2019: unresolved external symbol' mean?
 

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  1. POWhat does 'Error LNK2019: unresolved external symbol' mean?
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    <p>I'm trying to run a program but it won't compile, I get errors. I have changed things, but doesn't seem to work. The code is this:</p> <pre><code>#include &lt;iostream&gt; #include &lt;string&gt; #include "StackLS.h" using namespace std; int main() { int answer; char symbol; char n, N; StackLS stack; bool balenced = true; do { cout &lt;&lt; " ********** MENU ********** " &lt;&lt; endl; cout &lt;&lt; " 1. Basic Brackets () " &lt;&lt; endl; cout &lt;&lt; " 2. Standard Brackets ()[]{} " &lt;&lt; endl; cout &lt;&lt; " 3. User-Defined brackets " &lt;&lt; endl; cout &lt;&lt; " Please enter your choice: " &lt;&lt; endl; switch (answer){ case 1: cout &lt;&lt; "Current Setting: () " &lt;&lt; endl; cout &lt;&lt; "Enter your expression followed by a ; : " &lt;&lt; endl; cin &gt;&gt; symbol; do { if (symbol = '(') stack.push( '(' ); else if (symbol = ')' ) { if (stack.isEmpty()) balenced = false; else { symbol = stack.top(); stack.pop(); } if (balenced) cout &lt;&lt; "Expression is well-formed" &lt;&lt; endl; else cout &lt;&lt; "Expression is not well-formed" &lt;&lt; endl; } } while (symbol != ';' &amp;&amp; balenced); stack.pop(); } } while (answer != 'n' || 'N'); } // end main </code></pre> <p>I haven't finished the program. I wanted to make sure that what I have so far will compile before I move on to the next case. Now I will post the errors I am getting. They are:</p> <ol> <li><p>1>e:\c++ language 2\well-formed expression checker solution\well-formed expression checker project\main.cpp(11): warning C4101: 'n' : unreferenced local variable</p></li> <li><p>1>e:\c++ language 2\well-formed expression checker solution\well-formed expression checker project\main.cpp(11): warning C4101: 'N' : unreferenced local variable</p></li> <li><p>1>e:\c++ language 2\well-formed expression checker solution\well-formed expression checker project\main.cpp(22): warning C4700: uninitialized local variable 'answer' used</p></li> </ol> <p>1>ManifestResourceCompile: 1> All outputs are up-to-date.</p> <ol> <li><p>1>main.obj : error LNK2019: unresolved external symbol "public: int __thiscall StackLS::top(void)const " (?top@StackLS@@QBEHXZ) referenced in function _main</p></li> <li><p>1>main.obj : error LNK2019: unresolved external symbol "public: void __thiscall StackLS::push(int const &amp;)" (?push@StackLS@@QAEXABH@Z) referenced in function _main</p></li> <li><p>1>E:\C++ language 2\Well-Form ed Expression Checker Solution\Debug\Well-Formed Expression Checker Project.exe : fatal error LNK1120: 2 unresolved externals</p></li> </ol> <p>Thanks for the help.</p>
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    1. USPeter Wood
    1. USLea
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      1. POWhat does 'Error LNK2019: unresolved external symbol' mean?
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    1. COFrom the compiler error messages, I'd guess that 1) `n` is an unreferenced (unused) local variable, 2) `N` is an unreferenced local variable, and 3) `answer` is used before it is initialized. I'd recommend removing the unused locals and initializing `answer`, for starters.
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      1. POWhat does 'Error LNK2019: unresolved external symbol' mean?
      1. USAdam Mihalcin
    2. COThose are be warnings; the errors are coming from the linker. Looks like you haven't properly linked the StackLS library.
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      1. POWhat does 'Error LNK2019: unresolved external symbol' mean?
      1. UStmpearce
    3. COLea - paste your makefile here too please.
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      1. POWhat does 'Error LNK2019: unresolved external symbol' mean?
      1. USPreet Sangha
 

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