Accessing Files Programmer's Guide (32650-90885)

136 Chapter9

Reading from a File

Reading a File Label from a Labeled Tape File

FREADLABEL ( data_file, {file number of tape file}

label, {returns label }

length {# of halfwords to read}

);

if ccode <> cce then handle_file_error (data_file);

FWRITE ( list_file, {output to $STDLIST }

label, {label read by FREADLABEL }

length, {length of label }

control_code {default condition }

);

if ccode <> cce then handle_file_error (list_file);

end; {end read_user_label }

If an error is encountered by either FREADLABEL or FWRITE, procedure handle_file_error

is invoked. For more information about FREADLABEL intrinsic parameters, refer to the

MPE/iX Intrinsics Reference Manual. For more information about the FWRITE intrinsic,

refer to chapter 8, "Writing to a File". In appendix A, "HP Pascal/iX Program Examples",

example A-2 uses a similar procedure to read a user label from a labeled magnetic tape

ﬁle.