In RPGLE (RPG IV), effective error handling is crucial for creating robust and reliable programs. Here are some common strategies and techniques for handling errors in RPGLE:
1. Using the *PSSR Subroutine
The *PSSR subroutine is a special error-handling routine that gets executed automatically when an error occurs in the program.
rpg
**FREE
// Declare the *PSSR subroutine
PSSR:
// Handle the error
DSPLY ‘Error occurred: ‘ + %CHAR(%STATUS);
// End the program
*INLR = *ON;
RETURN;
2. Using MONITOR and ENDMON
The MONITOR and ENDMON block is similar to try-catch blocks in other programming languages. It allows you to handle specific errors.
rpg
**FREE
MONITOR;
// Code that might cause an error
EXEC SQL
SELECT field INTO :variable
FROM table
WHERE condition;
ON-ERROR;
// Handle the error
DSPLY ‘SQL Error: ‘ + %CHAR(SQLCODE);
ENDMON;
3. Using %ERROR BIF
The %ERROR built-in function can be used after certain operations to check if an error occurred.
rpg
**FREE
// Example with file operations
READ myFile;
IF %ERROR;
DSPLY ‘File read error: ‘ + %CHAR(%STATUS);
ENDIF;
4. Using Error Codes in SQL
When using embedded SQL, you can use the SQL communication area (SQLCA) to check for errors.
rpg
**FREE
// Declare SQLCA
DCL-DS SQLCA;
SQLCODE INT(10);
// Additional fields
END-DS;
// Execute SQL statement
EXEC SQL
SELECT field INTO :variable
FROM table
WHERE condition;
// Check for SQL errors
IF SQLCODE <> 0;
DSPLY ‘SQL Error: ‘ + %CHAR(SQLCODE);
ENDIF;
5. Using INFSR (Information Subroutine)
The INFSR is another way to handle file exceptions specifically.
rpg
**FREE
// Define a file with INFSR
FMYFILE IF E DISK INFDS(myFileDS);
// Declare INFDS data structure
DCL-DS myFileDS;
fileStatus CHAR(1);
// Other fields
END-DS;
// Example of using INFSR
READ myFile;
IF %ERROR;
DSPLY ‘File status code: ‘ + fileStatus;
ENDIF;
6. Handling CPF Messages
When dealing with system commands or APIs, you might need to handle CPF messages (system messages).
rpg
**FREE
// Example of calling a system command
CALLP(E) QCMDEXC(‘CRTUSRPRF USRPRF(TEST)’, 0000000024.00000);
// Check for CPF errors
IF %ERROR;
DSPLY ‘Command Error: ‘ + %CHAR(%STATUS);
ENDIF;
7. Logging Errors
Logging errors to a file or a database table can be useful for troubleshooting and auditing.
rpg
**FREE
// Example of logging errors to a database table
MONITOR;
// Code that might cause an error
EXEC SQL
INSERT INTO myTable (field)
VALUES (:value);
ON-ERROR;
// Log the error
EXEC SQL
INSERT INTO errorLog (errorCode, errorMessage)
VALUES (:SQLCODE, ‘Insert failed’);
ENDMON;
Combining Techniques
You can combine these techniques to create comprehensive error-handling mechanisms that cover different types of errors and exceptions in your RPGLE programs.
Effective error handling in RPGLE helps ensure that your programs run smoothly and can gracefully handle unexpected situations. If you have specific scenarios or need more detailed examples, feel free to ask!
