едит рандом филес BY рICHARD бAIN еDIT'WHEEL'DATA WAS WRITTEN AS A COMPANION PROGRAM TO THE WHEEL'OF'FORTUNE GAME. вITH A FEW SMALL CHANGES, IT CAN BE USED TO EDIT OTHER RANDOM FILES WITH ONE STRING PER RECORD. вHEN рун, IT FIRST ASKS FOR A FILENAME. тHE DEFAULT PROMPT, RAN.WHEEL, IS THE FILE USED WITH THE WHEEL'OF'FORTUNE GAME (SEE PAGE 56). тHE FILE IS THEN OPENED: OPEN FILE 2,FILENAME$+",R",RANDOM 41 тHE DESIRED FILE MAY NOT BE ON THE DISK BECAUSE THE WRONG DISK IS IN THE DRIVE OR THE FILENAME WAS TYPED INCORRECTLY. нORMALLY, WHEN цомал TRIES TO опен A рандом FILE THAT IS NOT ON THE DISK, IT WILL CREATE A NEW FILE ENTRY. тHIS IS OFTEN UNDESIRABLE. иT IS IMPORTANT TO CHECK IF THE FILE EXISTS BEFORE TRYING TO OPEN THE FILE, OR INCLUDE +",R". тHEN THE DISK DRIVE WILL RESPOND WITH A FILE NOT FOUND ERROR RATHER THAN CREATE A NEW FILE ENTRY. тHIS IS A FASTER METHOD TO OPEN AN EXISTING FILE BECAUSE THE FILE IS ONLY OPENED ONCE, NOT TWICE AS WITH THE FILE'EXISTS METHOD. а SECOND ADVANTAGE TO THIS METHOD IS THAT THE DISK DRIVE WILL GIVE A FILE TYPE MISMATCH ERROR IF THE FILE IS ON THE DISK, BUT IS NOT A рандом FILE. а DISADVANTAGE IS THAT IT IS NOT TRANSPORTABLE TO OTHER VERSIONS OF цомал. рANDOM 41 SPECIFIES THAT THE FILE RECORD LENGTH IS 41 BYTES. тHIS ALLOWS FOR 39 CHARACTERS PLUS 2 BYTES FOR THE CHARACTER COUNT AS USED BY RAN.WHEEL. оTHER FILES MAY NEED A DIFFERENT RECORD LENGTH. тHE MAXIMUM POSSIBLE LENGTH IS 254. еDIT'WHEEL'DATA THEN READS IN THE ENTIRE FILE. тHE FILE CONTAINS A SPECIAL FORMAT TO MAKE THIS EASY. тHE FIRST RECORD IN THE FILE CONTAINS, MAX'USED, THE NUMBER OF THE LAST VALID RECORD. оNCE MAX'USED IS DETERMINED, RECORDS 2 THROUGH MAX'USED CAN SAFELY BE реад. тHE PROGRAM MUST KEEP TRACK OF THE NUMBER OF RECORDS AND врите IT TO THE FIRST RECORD PRIOR TO CLOSING THE FILE. тHIS CAN SERVE AS A USEFUL STANDARD FOR ALL рандом FILES. тHE PROGRAM THEN ASKS IF YOU WANT TO EDIT THE DATA. тHIS OPTION LETS YOU CHANGE ANY EXISTING RECORD. тHE EDITING PROCESS IS EASY. тHE OLD ENTRY IS PRINTED ON THE SCREEN AND THE CURSOR IS PLACED ON THE FIRST CHARACTER. пRESS <ретурн> TO KEEP IT UNCHANGED, OR TYPE IN THE CHANGES YOU DESIRE. нOTE THAT STRINGS ARE LIMITED TO 39 CHARACTERS. аFTER YOU ARE FINISHED EDITING THE DATA, YOU HAVE THE OPTION OF ADDING MORE DATA (UP TO 100 RECORDS). тYPE IN THE NAMES AND PHRASES YOU WANT. вHEN YOU HAVE ENTERED ALL THE DATA, HIT <ретурн> ON A BLANK LINE TO TELL THE COMPUTER YOU ARE FINISHED. нEXT, YOU WILL BE ASKED IF YOU WANT ANY MORE CHANGES. и RECOMMEND YOU SAY YES. тHIS WILL LET YOU EDIT THE DATA AGAIN. еVEN IF YOU THINK IT IS RIGHT, THIS OPTION LETS KNOW BEFORE IT IS SAVED. вHEN THE DATA IS THE WAY YOU LIKE IT, YOU WILL BE ASKED IF YOU WANT TO SAVE IT. аLL CHANGES HAVE BEEN MADE IN COMPUTER MEMORY ONLY, SO YOU ALMOST CERTAINLY WILL WANT TO SAVE IT BACK TO THE DISK. тHE DEFAULT FILENAME IS THE ONE SPECIFIED AT THE START OF THE PROGRAM, BUT CAN BE CHANGED. иF YOU SPECIFY A FILENAME THAT IS NOT ON THE DISK, A NEW FILE WILL BE CREATED. [нOTE: IT IS POSSIBLE TO SWAP DISKS DURING THE PROGRAM, SO THIS OPTION CAN BE USED TO COPY THE FILE FROM ONE DISK TO ANOTHER. тHIS MAY BE IMPORTANT FOR THOSE OF YOU WHO DON'T HAVE A рандом FILE COPY PROGRAM.] тHE RECORDS ARE WRITTEN TO THE FILE IN REVERSE ORDER. вHEN CREATING A NEW рандом FILE, OR APPENDING TO AN OLD ONE, IT IS IMPORTANT TO врите THE LAST RECORD BEFORE THE OTHERS. тHEN THE FILE ONLY NEEDS TO ALLOCATE NEW RECORDS ONCE INSTEAD OF ALLOCATING EACH RECORD AS IT IS USED. рANDOM фILE пROBLEMS иT SEEMS THAT IF YOU принт филе A NUMBER TO A рандом FILE IN цомал 0.14, THE RECORD ENTRY WILL START WITH цхр$(13) AND THEN BE PADDED WITH цхр$(0)S. иN цомал 2.0, THE NUMBER IS PLACED IN THE RECORD, BUT THE REST OF THE RECORD IS STILL PADDED WITH цхр$(0)S, OVERWRITING ANYTHING WHICH MAY HAVE BEEN THERE BEFORE. тHE PROBLEMS SEEM TO DISAPPEAR WHEN USING реад филе AND врите филе. тHE 1541 HAS KNOWN BUGS WRITING TO рандом FILES. и TRY TO AVOID THEM BY READING BACK EACH RECORD RIGHT AFTER IT IS WRITTEN. тHIS SEEMS TO SOLVE THE PROBLEM. иF IT DOESN'T, AT LEAST THE PROGRAM STOPS WHEN THE ERROR OCCURS.