REXX Programming Fundamentals

In REXX, SAY with multiple arguments displays them separated by spaces. SAY "HELLO" "THERE" outputs 'HELLO THERE'. The || operator performs string concatenation without spaces, so SAY "HELLO" || "THERE" outputs 'HELLOTHERE'. The claimed result matches both outputs.

REXX string comparison is exact and space-sensitive. NAME1 contains 'JHON' (6 characters) while NAME2 contains ' JHON ' with leading and trailing spaces (8 characters). Since the strings are not identical, the condition NAME1 == NAME2 is false, triggering the ELSE branch that outputs 'NOT MATCHED'.

The REXX PARSE statement with a single variable template splits the input string by whitespace into sequential variables. PARSE VAR INPUT_STRING ONE TWO THREE parses 'HOW ARE YOU' by assigning the first word 'HOW' to ONE, second word 'ARE' to TWO, and third word 'YOU' to THREE.

The PARSE VALUE ... WITH instruction splits the string into words. B gets 'THIS', A gets 'IS', C gets 'A', and D gets 'SAMPLE'. Therefore, the value of the variable C is 'A'.

The PARSE UPPER ARG instruction processes the input string. 'LASTN' captures the first word, and the '.' (placeholder) consumes the rest of the string. For 'MEMORIAL DRIVE CAMBRIDGE', the first word 'MEMORIAL' is assigned to LASTN and converted to uppercase.

PARSE UPPER ARG LASTN FIRSTN assigns the first two words from 'MEMORIAL DRIVE CAMBRIDGE' in reverse: LASTN='MEMORIAL', FIRSTN='DRIVE'. The SAY FIRSTN statement outputs only the value of FIRSTN, which is 'DRIVE'. Any remaining input ('CAMBRIDGE') is unassigned and ignored.

The PARSE ARG instruction uses absolute column patterns. '1 VAR1 5' captures characters from column 1 up to (but not including) column 5, which is 'ABCD'. '7 VAR2 9' captures characters from column 7 up to (but not including) column 9, which is 'GH'.

In REXX, SIGL is a special variable automatically set by the interpreter to the line number of the instruction that caused a transfer of control (such as a CALL, a function invocation, or a SIGNAL instruction). This is extremely useful for error trapping and debugging.

The VERIFY function in REXX returns the position of the first character in the first string that is NOT present in the second string. Since every character in 'SUSAN' (S, U, A, N) is contained in 'ABNTUSV', the function finds no discrepancies and returns 0.

The TRUNC(number, n) function in REXX truncates a number to 'n' decimal places. If 'n' is larger than the current decimal count, it pads with zeros. TRUNC(1234.5, 3) results in 1234.500. It does not perform rounding.

SYSDSN is a TSO/E REXX function that checks whether a dataset exists in the system. It returns 0 if the dataset exists, and a non-zero value if it does not exist. Option C correctly describes this purpose.

The STRIP function in REXX removes leading and trailing blanks from a string. The second parameter 'B' means 'both' - strip from both beginning and end. So ' MUCH BLANK SPACE ' becomes 'MUCH BLANK SPACE' with all leading and trailing spaces removed.

LISTDSI is a TSO REXX function that retrieves comprehensive dataset information. It provides complete dataset information (A), retrieves RACF security details (C), and returns dataset attributes like space allocation, organization, and record format (D). Option B is incorrect as it doesn't list similar datasets.

The FORMAT(number, before, after) function in REXX formats a number. FORMAT(123.45, 5, 3) requests 5 spaces for the integer part (leading spaces added) and 3 decimal places (trailing zero added). This results in ' 123.450' (two leading spaces + three digits = 5 total 'before' positions).

The REXX FIND function returns the word number of the first word of the second string within the first string. In 'MARY HAD A LITTLE LAMB', the phrase 'A LITTLE LAMB' starts at the 3rd word ('A'). Therefore, the result is 3.

C2X (Character to Hexadecimal) converts each character to its hexadecimal ASCII representation. 'A' = C1 (hex), '1' = F1, '2' = F2, '3' = F3. Concatenating gives C1F1F2F3. This is the correct hexadecimal conversion of the string.

COMPARE returns the position of the first character where two strings differ. 'APPLES' and 'APPLESAUCE' are identical for the first 6 characters (APPLES), but at position 7, the first string ends while the second has 'A'. Therefore, COMPARE returns 7.

The PROCEDURE instruction in REXX creates a new variable scope, making all variables in the function/subroutine local by default. This means variables inside the procedure don't affect variables with the same name in the calling program unless explicitly exposed using the EXPOSE instruction.

EXPOSE is used with PROCEDURE to selectively allow specific variables to be shared between the main program and the procedure, overriding the default local scope. Options A and B are correct: EXPOSE allows variables A through n to be shared, and it is used with PROCEDURE instruction. Option C is incorrect as EXPOSE enables sharing, doesn't suppress it.