The do while loop makes the test for continuance at the bottom of the loop, rather than at the top. It looks like this:
int intCharPointer = 0; Filename.length = 4; do { // Do something. intCharPointer++; // Increment the CharPointer. } while(intCharPointer < Filename.Length);
In this case, Filename is a string with four characters in it. Its char positions are numbered 0, 1, 2, and 3. The first time through the loop, char 0 is checked for something and intCharPointer is incremented to 1. The loop loops again and checks char 1; intCharPointer is incremented to 2. The loop loops again and checks char 2; intCharPointer is incremented to 3. The loop loops again and checks char 3; intCharPointer is incremented to 4, and the while test at the bottom fails.