Lookout FAQ (hints)

LOOKOUT hints

This page supplies hints, in the form of a FAQ (Frequently Asked Questions) about how to use the LOOKOUT integrated programming environment (IDE) effectively.

First of all, there is lots of help online within LOOKOUT. See the Help menu on the right side of the menu bar. The first four items pertain to MicroEmacs for Windows (upon which the LOOKOUT IDE is based). The following two items give access to the README.TXT file for LOOKOUT and the info system the DJGPP port of Free Software Foundation's gcc compiler and related tools.

The rest of this document has the format of a FAQ (Frequently Asked Questions) list. Ask me more questions and I'll add to this list!

What do I do if LOOKOUT hangs up as soon as I press the F4 or F5 button to compile a program?
It's probably a PATH problem. See the answer to the next question.
What do I do if LOOKOUT complains that it cannot find the LRD or REDIR program when I try to compile a program?

UMPATH

D:

D:>cd \umach

D:\gcc>autobat D:

C:

cd \gcc

C:\gcc>gccsetup C:\gcc

Or if gcc has been installed on your CD-ROM, which is drive D:, enter:
   D:
   cd \gcc
   D:\gcc>gccsetup D:\gcc

(If you just enter gccsetup it will prompt you for the parameter it needs.) The gccsetup.bat batch file will make the changes needed to your autoexec.bat file, including the path to the REDIR or LRD program. Or you can use notepad to edit C:\autoexec.bat manually, so that the variables LOOKOUT, DJGPP, and PATH are all pointing at the right folders and files. Here are the settings on one of my machines:

set path=%path%;C:\gcc\bin set lookout=C:\gcc set djgpp=C:\gcc/djgpp.env

These all assume that gcc has been installed on hard drive C:. You can edit the above settings to point to another drive letter.

You should reboot after changing the PATH setting, so that it will take effect for subsequent compiles. The README.TXT file explains the setup requirements of LOOKOUT in more detail.

When I press the F4 or F5 key to compile a program, I get a message about detecting Windows 3.1, but I an running Windows NT! Until the summer of 1999, LOOKOUT simply was not designed for Windows NT. However, you may now download a new version of LOOKOUT which does work under Windows NT. Once you've downloaded it, just run the lookgcc setup program.

When I press the F4 key, it crashes. Should I abandon LOOKOUT and use some other compiler? The F4 key invokes the LOOKOUT parser, which Prof. Blank and several graduate students created to make sure that programs are within the C++-- subset. This has the advantage of producing a smaller set of error messages, which may be a little easier to understand than those of the full C++ language. However, if it doesn't work for you, just press F5 to bypass the LOOKOUT parser and invoke the gcc compiler directly. The gcc compiler is much stabler than the LOOKOUT parser. When I press the F4 key, it complains about legal C++ code, such as for loops or do...while loops. What if I want to create programs with these constructs? Once again, the F4 key invokes the LOOKOUT parser, which Prof. Blank and several graduate students created to make sure that programs are within the C++-- subset. If you want to go outside the subset, just press F5 to bypass the LOOKOUT parser and invoke the gcc compiler directly. When I press the F4 key, I get these error messages: > > twinkle.cc:0: unterminated string or character constant > twinkle.cc:0: possible real start of unterminated constant > twinkle.cc:9: '#include' expects "FILENAME" or <FILENAME> > fatal: Couldn't preprocess "twinkle.cc" Here's my program: > /*--------------------------------------twinkle.cc-------------------------- > #include <iostream.h> > #include <note.h> //header file for Lookout's Note Class The problem is that the LOOKOUT parser (F4) cannot handle comments on the same line as a preprocessor command. Drop the comment and it works. Or, bypass the parser by pressing F5. I remember in class you showed us a way to cut and paste in Lookout? Can you remind me how that works? 1) Set a mark (by pressing Esc space) at one end of the region you want to copy. 2) Move the cursor to the other end of the region you want to copy. 3) Press Ctrl-Ins to copy the region onto the Windows Clipboard. If you forget this, it's under the Edit pulldown menu (Edit>Clipboard in older versions). 4) Press Alt-Tab to switch to the other Windows application, such as Notepad. 5) Press Shift-Ins or Ctrl-V to paste from the Clipboard. If you're just copying and pasting within Lookout (MicroEmacs), there's are a couple of other ways: 1) Set a mark and move the cursor as above, then press Ctrl-w to delete a region. Then press Ctrl-y to yank it back. Move the cursor to another place to yank it back at some other location. Or press F1 to shift to another buffer, then Ctrl-y to yank it into another buffer. 2) Press Ctrl-k repeatedly to Kill lines. Then press Ctrl-y to yank all of them back, at the current location or some other location, as described above. Come to think of it, all this is described in the Help that comes with Lookout (MicroEmacs), accessible via the Help menu. Try it! LOOKOUT is a pretty versatile text editor, much more powerful than Notepad. Once you've learned how to use it, you'll also know a lot about how to use EMACS, a popular and powerful text editor. I tried pressing F1 as you described and the program would not let me do that. Probably, I don't understand how these various buffer concepts work. Could you explain? Before F1 will do anything interesting, you must have more than one file loaded into the editor. Each time you open a file (or LOOKOUT automatically opens a file), it opens another buffer. Pressing F1 switches to the next buffer. Perhaps you only had file open at the time, so nothing interesting happened. A buffer is a holding place in memory. In MicroEmacs, a buffer holds the contents of a file. The name of the buffer and the file it contains appears in the bottom of the LOOKOUT (MicroEmacs) window. Once you have several files loaded into buffers, keep pressing F1 to switch to the next buffer. It will cycle around when you've seen all of them. I was just wondering... how can i view the header file that you made to create Note? All the header files associated with LOOKOUT are in gcc\include. The full path to \gcc depends on how you installed it, either on the CD-ROM or a hard drive. On the LANs, the full path is y:\lib\gcc\include. How do debug a logic error in my program? It runs but the results aren't right. After you've compiled your program successfully, press F8 (or Lookout>Debug from the menu), to bring up the gdb debugger, which comes with the gcc compiler. LOOKOUT will ask you if you want to copy the library source code. Most of the time you do not want to do so; this is useful only if you want to debug the LOOKOUT library itself. So you usually answer NO (or press Enter since it's the default). LOOKOUT will then automatically invoke gdb, loading in the program compiled from the source program the current buffer. The gdb debugger is line-oriented, making it a little less intuitive than a GUI debugger, but it's quite powerful once you know how to use it. The most useful commands for you to start with are: list or l: Lists the source code of the program, with line numbers, starting from the current line. l 20 lists the line starting a line 20. Once you have the line numbers, you can set breakpoints. break or b #: Sets a breakpoint at the line #. I.e., b 10 sets a breakpoint a line 20. When you run a program in a debugger, it will stop at the next breakpoint. run or r: Begin executing the program from the beginning. It will stop at the first breakpoint encountered while running the program; if there are no breakpoints, it will to the completion of the program, unless the program crashes first. continue or c: Continue executing the program from the current breakpoint. Rather than restarting the program, this command resumes execution, stopping at the next breakpoint. step or s: Execute the next statement in the program. This allows you to watch the behavior of the program one step at a time. print or p variable-name: Print the current value of the variable-name. For example, p myName prints the current value of the variable myName. This may be a useful thing to do once the program has stopped at a breakpoint, to examine the state of the program at this point. up or u: Go up to the caller function, i.e., the one that called the function currently executing. down or d: Go back down to the callee function. help or h: Learn about other commands in gdb. It can provide more information with parameters: help with no arguments lists the classes of commands; help running lists all the commands that pertain to running a program; help run explains the run command. I get a DISK FULL message when I try to compile the program. Probably you are trying to compile a program on your floppy disk, drive A:, and you've run out of space. Because floppy disks can hold so little data and are so slow, I highly recommend that you store your files on the hard drive temporarily, then copy them to drive A: when you're done. LOOKOUT automatically copies files from the LAN or CD-ROM to C:\tmp; that might be a good place to work. If you're working in a public site, don't forget to delete your files from C:\tmp when you're done--LOOKOUT will automatically prompt you about this.