What does it mean if a "variable or field" is declared void? Error message help
<p>variable or field `letterGrade' declared void. This error message is coming up on the last iteration of the function 'letterGrade'. Anyone have an idea why? </p>

<pre><code>#include &lt;string&gt;
#include &lt;iostream&gt;
using namespace std;
void letterGrade (int score, string&amp; scoreLetter);
string scoreLetter;
int main()
{
    int score;
    char A, B, C, D, F;
    cout&lt;&lt;"Enter the grade: ";
    cin&gt;&gt; score;
    letterGrade (score, scoreLetter);
    cout&lt;&lt;"The letter grade is a(n) "&lt;&lt; scoreLetter&lt;&lt;".";
    system ("pause");
    return 0;
}
void letterGrade (score, scoreLetter)
{
     for (score &gt;= 90)
     {
             scoreLetter = 'A';}
      if (score == 100)
     {
             scoreLetter.insert (1, "+");
     } 
     else if (8&lt;=score% 10 &amp;&amp; score% 10 &lt;= 9)
     {
                   scoreLetter.insert (1, "+");
     else if (0&lt;=score% 10 &amp;&amp; score% 10 &lt;=1)
     {
                   scoreLetter.insert (1, "-");
     } 
</code></pre>
