As we have seen in the previous problem, character strings in Pascal have fixed length. However, we treat a string as having a varying length if we ignore all trailing blanks. Consider, for example,...

fast

Extracted text: As we have seen in the previous problem, character strings in Pascal have fixed length. However, we treat a string as having a varying length if we ignore all trailing blanks. Consider, for example, the following implementation: CONST STRSIZE = 80; TYPE STRING = RECORD WORD: PACKED ARRAY [1. STRSIZE] of CHAR; length:1.strsize END; where the field length represents the position of the last non trailing-blank character. For example, the string 'HELLOBB... 'has length 5 and 75 trailing blanks, and the string 'GOODbbbBYEbbb.' has length and 70 trailing blanks. Assuming the above definitions, write PROCEDURE SUBSTRING (S1:STRING; var S2:string; p,n: integer); which copies the first n characters, starting with position p in the string S1 into string S2. For example, if S1='ABCDEFGHIJbbb..', then after substring (S1, S2, 4, 3 ) S2 becomes ' DEFbb.'.