NsMutable string issue
<p>i am implementing a simple calculator. </p>

<p>Each time the user clicks digits buttons, the sender.tag is appended to a nsmutable string called displayString with is then displayed on screen.</p>

<p>The mutable string is initiated with size 40 ;</p>

<p>Strangely, after entering 10 digits , for example <code>1111111111</code> , the string behaves wrongly.</p>

<p>If you continue to click on the digit button '1', the string doesn't append '1' anymore, but another value, like, 2 or 6 ... and suddenly a number like <code>25469632154</code> appears!</p>

<p>Checked with the Debugger - the problem does not come from the display but from the string itself with is not correctly appended .</p>

<p>Could it be the <code>sender.tag</code> is not passed correctly ? </p>

<p>What could go wrong here ? </p>

<pre><code>[displayString appendString: [NSString stringWithFormat: @"%i", [sender tag]]];  
self.lblDisplay.text = displayString;
</code></pre>

<p>Thank you ALL in advance for your help.</p>
