error LNK2001: unresolved external symbol "float * num"
<p>Here is all of my code, it is supposed to be a simple calculator but I continue getting the following errors:</p>

<blockquote>
  <p>1>------ Build started: Project: calculator, Configuration: Debug Win32 ------
  1>  calculator.cpp
  1>calculator.obj : error LNK2001: unresolved external symbol "float * num" (?num@@3PAMA)
  1>C:\Users\Student\Desktop\User\calculator\Debug\calculator.exe : fatal error LNK1120: 1 unresolved externals</p>
</blockquote>

<pre><code>#include "stdafx.h"
#include &lt;iostream&gt;
#include &lt;string&gt;
using namespace std;

float num1 = 0;
float num2 = 0;
int x = 5;
int y;
int z;
float exponent;
float total = 0;
float num[];
string operation = (" ");
string power = (" ");
bool on = true;

void Total(){
    if(operation == ("addition") || operation == ("Addition")){
        cout &lt;&lt; "What is your first number?" &lt;&lt; endl;
        cin &gt;&gt; num1;
        cout &lt;&lt; "What is your second number?" &lt;&lt; endl;
        cin &gt;&gt; num2;
        total = num1 + num2;
    }
    else if(operation == ("subtraction") || operation == ("Subtraction")){
        cout &lt;&lt; "What is your first number?" &lt;&lt; endl;
        cin &gt;&gt; num1;
        cout &lt;&lt; "What is your second number?" &lt;&lt; endl;
        cin &gt;&gt; num2;
        total = num1 - num2;
    }
    else if(operation == ("multiplication") || operation == ("Multiplication")){
        cout &lt;&lt; "What is your first number?" &lt;&lt; endl;
        cin &gt;&gt; num1;
        cout &lt;&lt; "What is your second number?" &lt;&lt; endl;
        cin &gt;&gt; num2;
        total = num1 * num2;
    }
    else if(operation == ("division") || operation == ("Division")){
        cout &lt;&lt; "What is your first number?" &lt;&lt; endl;
        cin &gt;&gt; num1;
        cout &lt;&lt; "What is your second number?" &lt;&lt; endl;
        cin &gt;&gt; num2;
        total = num1 / num2;
    }
    else if(operation == ("exponent") || operation == ("Exponent")){
        cout &lt;&lt; "What is the base number?" &lt;&lt; endl;
        cin &gt;&gt; num1;
        cout &lt;&lt; "To what power are you raising it?" &lt;&lt; endl;
        cin &gt;&gt; num2 &gt;&gt; exponent;
        for(int exp = 0; exp &lt;= exponent; exp++){
            if(exp == 1){
                total = num1 * num1;
            }
            else{
                total = total * num1;
            }
        }
    }
}

void number(){
    cout &lt;&lt; "How many nunmbers will you be using?" &lt;&lt; endl;
    cin &gt;&gt; x &gt;&gt; z;
    for(y = 0; y &lt;= z; y++){
        cout &lt;&lt; "What is your number?" &lt;&lt; endl;
        cin &gt;&gt; num[x];
        x--;
    }
}

void start(){
    cout &lt;&lt; "What operation would you like to do:" &lt;&lt; endl;
    cout &lt;&lt; "addition, subtraction, multiplication, or division?" &lt;&lt; endl;
    cin &gt;&gt; operation;
}
void addition(){
    number();
    cout &lt;&lt; "The answer is: " &lt;&lt; total &lt;&lt; endl;
    start();
}
void subtraction(){
    number();
    cout &lt;&lt; "The answer is: " &lt;&lt; total &lt;&lt; endl;
    start();
}
void multiplication(){
    number();
    cout &lt;&lt; "The answer is: " &lt;&lt; total &lt;&lt; endl;
    start();
}
void division(){
    number();
    cout &lt;&lt; "The answer is: " &lt;&lt; total &lt;&lt; endl;
    start();
}
void Exponent(){
    number();
    cout &lt;&lt; "The answer is: " &lt;&lt; endl;
    start();
}
void Power(){
    cout &lt;&lt; "Would you like to continue: Yes or No?" &lt;&lt; endl;
    cin &gt;&gt; power;
}
int main(){
    start();
    while(on == true){
        if(operation == ("addition") || operation == ("Addition")){
            addition();
        }
        else if(operation == ("subtraction") || operation == ("Subtraction")){
            subtraction();
        }
        else if(operation == ("multiplication") || operation == ("Multiplication")){
            multiplication();
        }
        else if(operation == ("division") || operation == ("Division")){
            division();
        }
        else if(operation == ("exponent") || operation == ("Exponent")){
            Exponent();
        }
        else{
            cout &lt;&lt; "That is not a operation I recognize" &lt;&lt; endl;
            start();
        }
    }
    cout &lt;&lt; "Would you like to continue: Yes or No?" &lt;&lt; endl;
    cin &gt;&gt; power;
    Power();
    if(power == ("Yes") || power == ("yes")){
        on = true;
    }
    else if(power == ("No") || power == ("no")){
        on = false;
    }
    else{
        cout &lt;&lt; "That is not a word I recognize" &lt;&lt; endl;
        Power();
    }
}
</code></pre>
