ARexx Error Messages

When the ARexx interpreter detects an error in a program, it returns an error code to indicate the nature of the problem. Errors are normally handled by displaying the error code, the source line number where the error occurred and a brief message explaining the error condition. Unless the SYNTAX interrupt has been previously enabled (using the SIGNAL instruction), the program then terminates and control returns to the caller. Most syntax and execution errors can be trapped by the SYNTAX interrupt, allowing the user to retain and perform whatever special error processing is required. Certain errors are generated outside of the context of an ARexx program and therefore cannot be trapped by this mechanism. Refer to Chapter 6 for further information on error trapping and processing.

Each error code is associated with a severity level that is reported to the calling program as the primary result code. The values of these results codes are 5 (least serious), 10 (moderately serious), and 20 (very serious). The error code itself is returned as the secondary result. The subsequent propagation or reporting of these codes is dependent on the external (calling) program.

The following pages list all of the currently-defined error codes, along with the associated result code and message strings.

Error	Result Code	Message	Explanation
1	5	Program not found	The named program could not be found or was not an ARexx program. ARexx program are expected to start with a comment (`/…/`). This error is detected by the external interface and cannot be trapped by the `SYNTAX` interrupt.
2	10	Execution halted	A Ctrl+C break or an external halt request was received and the program terminated. This error will be trapped if the `HALT` interrupt has been enabled.
3	20	Insufficient memory	The interpreter was unable to allocate enough memory for an operation. Since memory space is required for all parsing and execution operations, this error cannot usually be trapped by the `SYNTAX` interrupt.
4	10	Invalid character	A non-ASCII character was found in the program. Control codes and other non-ASCII characters may be used in a program by defining them as hex or binary strings. This is a scan-phase error and cannot be trapped by the `SYNTAX` interrupt.
5	10	Unmatched quote	A closing single or double quote was missing. Check that each string is properly delimited. This is a scan-phase error and cannot be trapped by the `SYNTAX` interrupt.
6	10	Unterminated comment	The closing / of a comment was not found. Remember that comments may be nested, so each / must be matched by a */. This is a scan-phase error and cannot be trapped by the `SYNTAX` interrupt.
7	10	Clause too long	A clause was too long for the internal buffer. The source line should be broken into smaller parts. This is a scan-phase error and cannot be trapped by the `SYNTAX` interrupt.
8	10	Invalid token	An unrecognized lexical token was found, or a clause could not be properly classified. This is a scan-phase error and cannot be trapped by the `SYNTAX` interrupt.
9	10	Symbol or string too long	An attempt was made to create a string longer than the maximum allowed.
10	10	Invalid message packet	An invalid action code was found in a message packet sent to the ARexx resident process. The packet was returned without being processed. This error is detected by the external interface and cannot be trapped by the `SYNTAX` interrupt.
11	10	Command string error	A command string could not be processed. This error is detected by the external interface and cannot be trapped by the `SYNTAX` interrupt.
12	10	Error return from function	An external function returned a non-zero error code. Check that the correct parameters were supplied to the function.
13	10	Host environment not found	The message port corresponding to a host address string could not be found. Check that the required external host is active.
14	10	Requested library not found	An attempt was made to open a function library included in the Library List, but the library could not be opened. Check that the correct name and version of the library were specified when the library was added to the resource list.
15	10	Function not found	A function was called that could not be found in any of the currently accessible libraries and could not be located as an external program. Check that the appropriate function libraries have been added to the Libraries List.
16	10	Function did not return a value	A function was called which failed to return a result string, but did not otherwise report an error. Check that the function was programmed correctly or invoke it using the `CALL` instruction.
17	10	Wrong number of arguments	A call was made to a function which expected a different number of arguments. This error will be generated if a built-in or external function is called with more arguments than can be accommodated in the message packet used for external communications.
18	10	Invalid argument to function	An inappropriate argument was supplied to a function or a required argument was missing. Check the parameter requirements specified for the function.
19	10	Invalid `PROCEDURE`	A `PROCEDURE` instruction was issued in an invalid context. Either no internal functions were active or a `PROCEDURE` had already been issued in the current storage environment.
20	10	Unexpected `THEN` or `WHEN`	A `WHEN` or `THEN` instruction was executed outside of a valid context. The `WHEN` instruction is valid only within a `SELECT` range, and `THEN` must be the next instruction following in `IF` or `WHEN`.
21	10	Unexpected `ELSE` or `OTHERWISE`	An `ELSE` or `OTHERWISE` was found outside of a valid context. The `OTHERWISE` instruction is valid only within a `SELECT` range. `ELSE` is valid only following the `THEN` branch of an `IF` range.
22	10	Unexpected `BREAK`, `LEAVE` or `ITERATE`	The `BREAK` instruction is valid only within a `DO` range or inside an `INTERPRET`ed string. The `LEAVE` and `ITERATE` instructions are valid only within an iterative `DO` range.
23	10	Invalid statement in `SELECT`	An invalid statement was encountered within a `SELECT` range. Only `WHEN`, `THEN` and `OTHERWISE` statements are valid within a `SELECT` range, except for the conditional statements following `THEN` or `OTHERWISE` clauses.
24	10	Missing or multiple `THEN`	An expected `THEN` clause was not found or another `THEN` was found after one had already been executed.
25	10	Missing `OTHERWISE`	None of the `WHEN` clauses in a `SELECT` succeeded, but no `OTHERWISE` clause was supplied.
26	10	Missing or unexpected `END`	The program source ended before an `END` was found for a `DO` or `SELECT` instruction, or an `END` was encountered outside a `DO` or `SELECT` range.
27	10	Symbol mismatch	The symbol specified on an `END`, `ITERATE` or `LEAVE` instruction did not match the index variable for the `DO` range. Check that the active loops have been nested properly.
28	10	Invalid `DO` syntax	An invalid `DO` instruction was executed. An initializer expression must be given if a `TO` or `BY` expression is specified. A `FOR` expression must yield a non-negative integer result.
29	10	Incomplete `IF` or `SELECT`	An `IF` or `SELECT` range ended before all of the required statements were found. Check whether the conditional statement following a `THEN`, `ELSE` or `OTHERWISE` clause was omitted.
30	10	Label not found	A label specified by a `SIGNAL` instruction or implicitly referenced by an enabled interrupt could not be found in the program source. Labels defined dynamically by an `INTERPRET` instruction or by interactive input are not included in the search.
31	10	Symbol expected	A non-symbol token was found where only a symbol token is valid. The `DROP`, `END`, `LEAVE`, `ITERATE` and `UPPER` instructions may only be followed by a symbol token. This message will also be issued if a required symbol is missing.
32	10	Symbol or string expected	An invalid token was found in a context where only a symbol or string is valid.
33	10	Invalid keyword	A symbol token in an instruction clause was identified as a keyword, but was invalid in the specific context.
34	10	Required keyword missing	An instruction clause required a specific keyword token to be present, but it was not supplied. This message will be issued if a `SIGNAL ON` instruction is not followed by one of the interrupt keywords (e.g., `SYNTAX`).
35	10	Extraneous characters	A seemingly valid statement was executed, but extra characters were found at the end of the clause.
36	10	Keyword conflict	Two mutually exclusive keywords were included in an instruction clause, or a keyword was included twice in the same instruction.
37	10	Invalid template	The template provided with an `ARG`, `PARSE` or `PULL` instruction was not properly constructed.
38	10	Invalid `TRACE` request	The alphabetic keyword supplied with a `TRACE` instruction or as the argument to the `TRACE()` built-in function was not valid.
39	10	Uninitialized variable	An attempt was made to use an uninitialized variable while the `NOVALUE` interrupt was enabled.
40	10	Invalid variable	An attempt was made to assign a value to a fixed symbol.
41	10	Invalid expression	An error was detected during the evaluation of an expression. Check that each operator has the correct number of operands and that no extraneous tokens appear in the expression. This error will be detected only in expressions that are actually evaluated. No checking is performed on expressions in clauses that are being skipped.
42	10	Unbalanced parentheses	An expression was found with an unequal number of opening and closing parentheses.
43	10	Nesting limit exceeded	The number of subexpressions in an expression was greater than the maximum allowed. Simplify the expression by breaking it into two or more intermediate expressions.
44	10	Invalid expression result	The result of an expression was not valid within its context. This message will be issued if an increment or limit expression in a `DO` instruction yields a non-numeric result.
45	10	Expression required	An expression was omitted in a context where one is required. For example, the `SIGNAL` instruction, if not followed by the keywords `ON` or `OFF`, must be followed by an expression.
46	10	Boolean value not `0` or `1`	An expression result was expected to yield a Boolean result, but evaluated to something other than `0` or `1`.
47	10	Arithmetic conversion error	A non-numeric operand was used in an operation requiring numeric operands. This message will also be generated by an invalid hex or binary string.
48	10	Invalid operand	An operand was not valid for the intended operation. This message will be generated if an attempt is made to divide by `0` or if a fractional exponent is used in an exponentiation operation.

ARexx Error Messages

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