Portability Functions: Return the current position of a file.
result = FTELL (lunit)
result = FTELLI8 (lunit)
(Input) INTEGER(4). External unit number of a file.
The result type is INTEGER(4) for FTELL; INTEGER(8) for FTELLI8. The result is the offset, in bytes, from the beginning of the file. A negative value indicates an error, which is the negation of the IERRNO error code. The following is an example of an error code:
EINVAL: lunit is not a valid unit number, or is not open.