The typical strcat code you see in the wild:<p>char buf[100];
 buf[0] = &#x27;\0&#x27;;
 strcat(buf, &quot;Hello&quot;);
 strcat(buf, &quot; &quot;);
 strcat(buf, &quot;World&quot;);
 strcat(buf, &quot;!\n&quot;);<p>The inefficiency is that each time you do strcat, the existing characters of the string are iterated. So something like a common sequence of building a string by appending little pieces has quadratic inefficiency.