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Text File | 1986-11-13 | 12.8 KB | 309 lines

Thread An On-Line C Help File Version 1.01 Copyright (c), 1986 Fran Horvath Abstract Thread is a C language help utility. It was written by a member of the U.S.D.A. Grad School faculty to help students learning the C language. Thread is a variable record-length database, together with an index, that enables fast look up and display of C keywords, standard library functions, and other items. Usage summary Operation of thread is self explanatory. - Simply enter "thread" at the DOS level. - When the menu screen appears, type in the keyword, operator, or function desired as shown on the menu. Only the first 5 characters are required, but you may enter the complete entry if you choose. - If you make a typing error, the item will not be found in the search list, and the menu screen will redisplay. To correct an error, you may use the function keys as in DOS. For faster reference, you may also use command line arguments at the DOS level to look up entries. Features Thread contains two features that are unusual in a help facility. (1) Thread will accept lookup items from the command line. That is, enter: thread precedence on the command line, and you'll receive a quick screenful of the C language precedence table. Thread will accept more than one item on the command line, and look up each in sequence. In other words, enter: thread char short int long float double and thread will provide a quick survey of C's variable storage types. The multiple command line argument feature can be used to dissect a line of C code into its major components. For example, enter the line thread while (fahr <= upper) { and thread will show screens of information about the "while" keyword, and the the "<=" operator. The other items will not be found in the help file and will be passed over. Be sure to use a space between keywords and operators if using this option. Thread will not find matches in the line thread printf("\nitem",name); because it will treat the item as a single word argument. (Maybe a future version....) (2) At any time, when the help screen is shown, it's possible the help item may contain a "thread". A thread is a related keyword or concept that may help clarify the meaning of the current search item. When an item contains a thread, the continuation message at the bottom of the screen will read: Press space to continue, T to follow thread, Esc to quit Press the 't' key, (upper or lower case accepted), and thread will search for the related item immediately and display its help screen. The thread option will not terminate the command line argument sequence. The processing of command line items will resume when when you choose to stop threading, or when there are no further thread items to follow. DOS redirection characters Since DOS intercepts the characters '|', '<' and '>' for purposes of redirecting files, some special handling of these characters had to be added. If the string you are seeking contains one of these special characters and you wish to enter it from the command line, place double quotes around the argument. That is: thread ">>" void "|" would look up the >> operator, the word void, and then the | operator. No quotes are necessary when using lookup from the main menu. Processing search items When you enter a search item at the menu prompt, thread strips all blanks from your response. Entries of: char,char , and c h a r are all equivalent. If you make a typing error entering a search item, you can use the function keys F1, F2, and F3 together with the backspace, insert, and delete keys as in standard DOS command editing. Exiting thread After presenting the help screen, thread will prompt for a carriage return to return to the menu, possibly a thread item, or the Esc key. Entering a carriage return will return the user to the main menu. Entering escape will exit the program immediately, and leave the help screen on the user's screen. If you use a editor like Sidekick's note facility, you can then see both the upper part of the help screen and your own work file. Seeing the correct syntax along with the file you're working on may be useful. Thread may also be exited by entering a carriage return at the main menu prompt. A Ctrl-Brk at any time will also terminate thread. Installation The easiest way to operate thread is simply to place the three files THREAD.EXE, THREAD.DAT, and THREAD.NDX in your current working directory. A good choice for the location of THREAD might be the directory that contains your C compiler or interpreter. THREAD can also be installed on your system so that it can be invoked from any current working directory. To do so, place THREAD.EXE in a directory included in your DOS path, or change your path to pass through the directory that holds THREAD.EXE. In addition, you need to create a DOS environment variable to indicate the directory location of the files THREAD.DAT and THREAD.NDX. To do so, use the DOS SET command to establish a variable called THREAD that gives the fully qualified directory name of the directory where you have placed THREAD.DAT and THREAD.NDX files. For example, if you had placed all 3 of the THREAD files on a hard disk identified as drive C: in a directory named C_HELP, you should enter the DOS command: SET THREAD=C:\C_HELP and make sure that your current path includes the C_HELP directory. For example, one path meeting this requirement would be: PATH=C:\BIN;C:\C3;C:\C_HELP Another example, for those with ample memory space, is to place the files THREAD.DAT and THREAD.NDX on a RAM drive, and to include the THREAD.EXE file somewhere in the current path. The program works very quickly in this configuration. If THREAD.EXE were located in C:\BIN, and the DAT and NDX files on a RAM drive identified as D:, a sample setup might be: PATH=C:\;C:\C3;C:\BIN SET THREAD=D: The program checks the environment for the THREAD variable before it looks in the current working directory. Thus, if you use the SET THREAD option, it will have to be correct, even if the files are subsequently moved into the same working directory. To disable the THREAD variable, enter the command SET THREAD= at the DOS level, which will erase the value from the DOS environment. If you use THREAD frequently, you can add the SET and PATH commands to your AUTOEXEC.BAT file. Since the program THREAD.EXE is not itself memory resident, it will not conflict with any memory resident programs you use. The order of placement of the SET THREAD command within the autoexec file is of no importance. If you wish, you can rename the .EXE file to a shorter name, or one that you find more appropriate. However, the .DAT and .NDX filenames and the environment variable THREAD are hard-coded and should not be renamed. C_COURSE.BAT A file named C_COURSE.bat is included with the package. It is a DOS batch file which repeatedly executes thread, with items laid out in the order they might be presented in a typical C course. The easiest way to use C_COURSE is to continually press the return key to step through the entire listing. The batch file can provide a quick summary of C. Resist the urge to rewrite the help file The help file is accessed via the thread.ndx file, which contains the offset of the search item in the thread.dat text file. If you are dissatisfied with any of the explanations or examples given in the help screens, you may feel a need to access the thread.dat file and edit the offending screen. Please don't. Any change in the thread.dat file will invalidate the thread.ndx file and cause the program to search through inappropriate locations in the text file. If you are dissatisfied with an explanation or example shown, please write: Fran Horvath 2524 N. Key Blvd. Arlington, VA. 22201 (Compuserve ID 75265,1117 ) with comments or complaints. Any corrections or changes you would like to see made will be considered, and will certainly improve any future versions released. Acknowledgements Thread was compiled using Microsoft C, version 3.0. Thread originated as a homework assignment for adults in USDA's C Programming class, ECOMP 275 in the Fall of 1985. Students were asked to write up descriptive screens for individually assigned keywords, operators, and functions. I am grateful to those students who participated in the exercise by completing some form of usable description. Those screens formed the core around which the program was designed. In the course of a year, however, every screen has been substancially edited or compeletely rewritten, so that any resemblance to the originals are purely coincidental. An assembly screen writing routine was used to speed up screen displays. The original routine was the product of Brian Foley, David B. Rein, and Michael D. Most. The version used here is a modified routine which changes end-of-line processing for both color and monochrome monitors. The idea for the index creation routine was suggested by a package provided by Philip Mongelluzzo, named BOSS0508.ARC. The program used in connection with this package was a modification of the index program presented there. The index generation routine is not included with the THREAD package. I'm grateful to Pete Olympia and Bob Blacher for their reviews and comments on a pre-release version of THREAD. The "K & R" reference at the top right of the display screen refer to the book: The C Programming Language, by Brian W. Kernighan and Dennis M Ritchie, Prentice Hall Software Series, 1978. No connection with or approval by these authors is implied by the reference. It is included solely for those wishing to find more details about a particular concept. While this program was written for the use by students in USDA class ECOMP 275, no approval or authorization by the USDA Grad School is implied by this connection. The author takes sole responsibility for content here, and any remaining errors or misstatements. Revision history Version 1.01 11-07-86 - Shortened required user input to 5 characters - Added THREAD environment option Copyright and disclaimer THREAD and this documentation are copyrighted by the author. THREAD is intended for PRIVATE, NONCOMMERCIAL USE ONLY. You may make copies of the program and the documentation for your own use, and may copy the files for others. You may not, however, charge for such copies, or in any other way sell the program or otherwise attempt to make money from it, or any modified version of it. An institution, professional organization, training program or special class conducted for profit may NOT use or distribute THREAD as part of its instructional material, unless it submits a one-time payment equal to the minimum registration amount required of a participant for attending the program. An exception to the above is granted to RECOGNIZED USER'S GROUPS, which are hereby authorized to charge a small amount (not to execeed $8.00) for media, postage and handling. I do not warrant that the program is accurate, or that it operates as claimed here. I will not be liable for any damages of any kind sustained through the use of the program, or because of the information in the program. By using the program, you agree to these conditions.