OSREAD

OSREAD reads an OS file.

COMMAND SYNTAX

    OSREAD Variable FROM expression { ON ERROR Statements }  \
          { THEN | ELSE } Statements

SYNTAX ELEMENTS

Variable specifies the variable which is to be assigned to the read data.

Expression specifies the full file path. If the file resides in the JEDIFILEPATH then just the file name is required.

ON ERROR Statements are conditional jBC statements to be executed when the OSREAD statement fails with fatal error (because the file is not open), I/O error, or jBASE cannot find the file. If you do not specify the ON ERROR clause and a fatal error occurs, the program will terminate.

THEN | ELSE: If the OSREAD statement fails, it will execute any statements associated with an ELSE clause. If the OSREAD is successful, it will execute any statements associated with a THEN clause. Note that the syntax requires either one or both of the THEN and ELSE clauses.

WARNING

Do not use OSREAD on large files. The jBC OSREAD command reads an entire sequential file and assigns the contents of the file to a variable. If the file is too large for the program memory, the program aborts and generates a runtime error message. On large files, use OSBREAD or READSEQ. jBASE uses the ASCII 0 character (CHAR (0)) as a string-end delimiter. ASCII 0 is not useable within string variable in jBC. This command converts CHAR(0) to CHAR(128) when reading a block of data.

NOTE

OSREAD doesn't include the LF character after the last line in the file to the resulting variable:

TAFJ note: OSREAD statement doesn't work - ELSE clause is always triggered.

EXAMPLE

       V.DIR.OUT = '.'  ;   V.FILE.OUT = 'report.txt'
       OPENSEQ V.DIR.OUT, V.FILE.OUT TO F.FILE.OUT THEN
          WEOFSEQ F.FILE.OUT
       END ELSE
          CREATE F.FILE.OUT ELSE CRT 'File create error'  ;  STOP
       END
       V.BUFFER = STR('.', 999)
       LOOP
          WRITESEQ V.BUFFER TO F.FILE.OUT ELSE CRT 'Write error'  ;  STOP
          V.FILE.SIZE = DIR(V.FILE.OUT)<1>
          CRT V.FILE.SIZE
       UNTIL V.FILE.SIZE GE 10000
       REPEAT
       CLOSESEQ F.FILE.OUT
       OSREAD V.ALL FROM V.FILE.OUT ELSE CRT 'Read error'  ;  STOP
       CRT LEN(V.ALL)
       CRT DQUOTE( RIGHT(V.ALL, 20) )

Output: 

     1000
     2000
     3000
     4000
     5000
     6000
     7000
     8000
     9000
     10000
     9999
     "...................."

Last update: Tue, 30 Aug 2022 15:47