i need problem. looks stupid not resolved it. have entry sequenced file variable length records. need replace first 3 bytes xxx have rebuild whole file this.. problem getting changing length of records filling "nulls". that's why have no way know amount of bytes written record.
for example have file 3 records:
aaaaaaaaaaaaaaaa bbbbbbbbbbbbbbbbbbbbbbbbbb ccccc dddddddddddddd the file has rec attribute of 26 (equals length of second record). when execute program change first 3 letters, file remains (assume "n" "null character"):
aaaaaaaaaaaaaaaannnnnnnnnn bbbbbbbbbbbbbbbbbbbbbbbbbb cccccnnnnnnnnnnnnnnnnnnnnn ddddddddddddddnnnnnnnnnnnn how can change program want?
xxxaaaaaaaaaaaaa bbbbbbbbbbbbbbbbbbbbbbbbbb ccccc dddddddddddddd this code (java)
enscribefile p_origin = new enscribefile(file); string first_record; byte buffer[]; //first, charge records , purge file content arraylist<byte[]> records = new arraylist<byte[]>(); buffer = new byte[et.getrecordlength()]; p_origin.open(enscribeopenoptions.read_write,enscribeopenoptions.shared); enscribefileattributes et = p_origin.getfileinfo(); while ( p_origin.read(buffer,et.getrecordlength()) != enscribefile.position_unused ) { byte auxrecord[] = new byte[et.getrecordlength()]; system.arraycopy(buffer,0,auxrecord,0,et.getrecordlength()); buffer = new byte[et.getrecordlength()]; records.add(auxrecord); } p_origin.purgedata(); //second, modify first record first_record = new string(records.get(0)); first_record = "xxx" + first_record.substring(3); records.set(0,first_record.getbytes()); //third, rewrite records , close file iterator<byte[]> = records.iterator(); while( i.hasnext() ) p_origin.write(aux,et.getrecordlength()); //check note p_origin.close(); note: can not add function last character before first null before write becouse previous null or nulls @ end of records possible , acceptable. example (remember "n" "null"):
aaaaaaaaaaaaaaaann bbbbbbbbbbbbbbbbbbbbbbbbbb cccccnn ddddddddddddddnn must equal after process:
xxxaaaaaaaaaaaaann bbbbbbbbbbbbbbbbbbbbbbbbbb cccccnn ddddddddddddddnn
ok, found solution @ other forum. simple. method
p_origin.read(...) returns length of bytes did not know, simple save variable length before creating new record. changes code becomes:
enscribefile p_origin = new enscribefile(file); string first_record; byte buffer[]; //first, charge records , purge file content arraylist<byte[]> records = new arraylist<byte[]>(); buffer = new byte[et.getrecordlength()]; p_origin.open(enscribeopenoptions.read_write,enscribeopenoptions.shared); enscribefileattributes et = p_origin.getfileinfo(); int aux_len = p_origin.read(buffer,et.getrecordlength()); while ( aux_len != enscribefile.position_unused ) { byte auxrecord[] = new byte[aux_len]; system.arraycopy(buffer,0,auxrecord,0,et.getrecordlength()); records.add(auxrecord); aux_len = p_origin.read(buffer,et.getrecordlength()); } p_origin.purgedata(); //second, modify first record first_record = new string(records.get(0)); first_record = "xxx" + first_record.substring(3); records.set(0,first_record.getbytes()); //third, rewrite records , close file iterator<byte[]> = records.iterator(); while( i.hasnext() ) { byte aux_byte[] = i.next(); p_origin.write(aux_byte,aux_byte.length); } p_origin.close(); 
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