Reading Text Files a Character at a Time

You can use the CHARIN and other character methods on text files. Because you read the file as characters, CHARIN returns the line-end characters to your program. Line methods, on the contrary, do not return the line-end characters to your program. Rexx adds line-end characters to the end of every line written using the LINEOUT method. Text-processing applications, such as the Windows Notepad, also add line-end characters. As a convenience, Rexx has an environment symbol name .ENDOFLINE that returns the line-end characters used by the Stream class on the current system. When reading a text file with CHARIN, interpret the character sequence in .ENDOFLINE as the end of a line.

As an example, run the following program. It writes lines to a file using LINEOUT and then reads those lines using CHARIN. You can mix line methods and character methods. Rexx maintains separate read and write pointers, so there is no need to close the file or search for another position before reading the lines just written.

/* linechar&per;cmd - demonstrate line end characters */"test.dat") /* Create a new stream object */
file~open("both replace") /* Open the file for reading and writing */
do i=1 to 3 /* Write three lines to the file */
file~lineout("Line" i)
end /* do */
do while file~chars&gt.&lt.0 /* Read the file a character at a time */
byte=file~charin /* Read a character */
ascii_value=byte~c2d /* Convert character to a decimal value */
if ascii_value=13 then /* Carriage return? */
say "Carriage return"
else if ascii_value=10 then /* Line feed? */
say "Line feed"
else say byte ascii_value /* Ordinary character */
end /* do */
file~close /* Close the file */

It is not recommended to use line methods to read binary files. Your binary file might not contain any new-line characters. And, if it did, the characters probably are not meant to be interpreted as new-line characters.