How to assign value to a c++ string index by index
<p>How to assign value to a c++ string index by index. I have tried this code but this is not changing the value of the string. </p>

<pre><code>#include &lt;iostream.h&gt;
#include &lt;string&gt;

void change(string &amp; str)
{
    str[0] = '1';
    str[1] = '2';
    // str = "12" ; // it works but i want to assign value to each index separately. 
}
void main()
{
    string str;
    change(str);
    cout &lt;&lt; str &lt;&lt; endl; // expected "12"
}
</code></pre>