jwf0978@tahoma.UUCP (John W. Fawcett) (05/18/88)
I have what may actually be a simple question, but I could not find an answer in my K & R. I would like to be able to tab over to a certain position on a line and place some text there without overwriting text that was already on the line, similar to the "X" format descriptor in FORTRAN. The closest I can come so far is to use a "%20s", but this overwrites whatever was there. Any help out there? Thanks, John John W. Fawcett Voice: (206) 237-2564 Boeing Commercial Airplanes UUCP: ..!uw-beaver!ssc-vax!shuksan!tahoma!jwf0978 P.O. Box 3707, M/S 66-04 Seattle, WA 98124-2207
chris@mimsy.UUCP (Chris Torek) (05/19/88)
In article <242@tahoma.UUCP> jwf0978@tahoma.UUCP (John W. Fawcett) writes: >... I would like to be able to tab over to a certain position on a >line and place some text there without overwriting text that was >already on the line, similar to the "X" format descriptor in FORTRAN. >The closest I can come so far is to use a "%20s", but this overwrites >whatever was there. Do what FORTRAN does: print on a card punch or line printer. Then those pesky spaces will not overwrite the non-spaces. :-) Seriously, most FORTRAN implementations have no idea how to back up; they simply keep track of the current column, and when asked to get to column 30 (via T, not X: X means blanks), print 30-current_column blanks. This approach works fine in C as well, but you have to count the columns yourself. Your operating system (which is not part of the C language) most likely provides a higher-level screen management library, if you have more ambition. -- In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163) Domain: chris@mimsy.umd.edu Path: uunet!mimsy!chris
jep@oink.UUCP (James E. Prior) (05/25/88)
In article <242@tahoma.UUCP> jwf0978@tahoma.UUCP (John W. Fawcett) writes: >I have what may actually be a simple question, but I could not find an >answer in my K & R. I would like to be able to tab over to a certain >position on a line and place some text there without overwriting text that >was already on the line, similar to the "X" format descriptor in FORTRAN. >The closest I can come so far is to use a "%20s", but this overwrites >whatever was there. Any help out there? > > Thanks, > John > >John W. Fawcett Voice: (206) 237-2564 >Boeing Commercial Airplanes UUCP: ..!uw-beaver!ssc-vax!shuksan!tahoma!jwf0978 printf() is pretty simple. It is so simple that it doesn't know or care what column you're at on a line. The following trick, albeit ugly, might work: printf("...\r%*s...",...,width,"",...); I admit to not having tried it. If it works, but it still too ugly, or unsuitable due to the overprinting, you'll probably have to resort to something else than printf(). Good luck, -- Jim Prior {ihnp4|osu-cis}!n8emr!oink!jep jep@oink.UUCP Pointers are my friend.
cpp90221@dcscg1.UUCP (Duane L. Rezac) (05/26/88)
In article <242@tahoma.UUCP>, jwf0978@tahoma.UUCP (John W. Fawcett) writes: > .... I would like to be able to tab over to a certain > position on a line and place some text there without overwriting text that > was already on the line..... NOTE: our posting program indicated that my original attempt at posting this may not have made it out, so I am posting it with a diffrent program. If this is a duplicate posting, my appologies. I am a newcomer to C, just finishing my first class in C, but this may help. If you are using an ansi terminal, this code may help. I wrote this printl function in order to let me print to a specific screen position. If you are trying to print to a printer, you could replace the ansi cursor movement statement with the appropriate command sequence for your printer. (If someone knows a better way to do this, Please post it. As I said, I am a novice at C and there may be better ways to do this.) /* printl - print at location x,y x,y = screen position, control=printf template, args=data to be printed This is used just like printf except that an x,y screen position is passsed. (i.e. printl(10,10,"%s",name) prints the string name at column 10, row 10)*/ printl(x,y,control,args) unsigned char *control; unsigned args; int x,y; { printf("\33[%d;%dH",x,y); /* prints ansi cursor movement command to stdout*/ printf(control,args); /* print data */ } I hope this helps.
shankar@hpclscu.HP.COM (Shankar Unni) (05/27/88)
Or even uglier and simpler, try programming direct escape sequences if it is
a terminal application:
printf ("\033&a%dC%s", column, text); /* HP escape sequences here.. */
Drawbacks:
1. Non-portable.
2. Ugly.
If you *really* want to do a portable terminal-based application, use "curses"
or any of its equivalents.
If you want to do this rigmarole with disc files, try some dorktran-like
carriage-control mechanism:
printf ("%cRESTofFORMAT", CCTL, ...);
/*
* where CCTL ==
* ' ' for normal pre-spacing (i.e. start next line)
* '0' for normal double-spacing
* '+' for overstrike (write over current line with
* NON-DESTRUCTIVE spacing..
* '1' for page eject
* any other char implies a ' ' (may or may not be eaten up).
* or anything else that strikes your fancy
*/
Then, write a post-processor to translate all this to simple text files
(should be pretty simple). Can even be built in to your application...
Shankar Unni.chris@mimsy.UUCP (Chris Torek) (05/29/88)
In article <284@dcscg1.UUCP> cpp90221@dcscg1.UUCP (Duane L. Rezac) writes: >(If someone knows a better way to do this, Please post it. ... Okay: >printl(x,y,control,args) >unsigned char *control; >unsigned args; >int x,y; >{ > printf("\33[%d;%dH",x,y); /* prints ansi cursor movement command to stdout*/ > printf(control,args); /* print data */ >} x and y are actually used as row and column respectively; so this should be `y, x' or `row, col'. In addition, you should use `vprintf' if you have it, so as to have the correct types and number of arguments at all times. Also, the control (format) argument should be `char *'. #include <stdio.h> #include <varargs.h> int #ifdef __STDC__ rcprint(int row, int col, char *fmt, ...) /* dpANS */ #else rcprint(va_alist) /* K&R &/ va_dcl #endif { int nchars; va_list ap; #ifndef __STDC__ int row, col; /* K&R */ char *fmt; va_start(ap); row = va_arg(ap, int); col = va_arg(ap, int); fmt = va_arg(ap, char *); #else va_start(ap, fmt); /* dpANS */ #endif nchars = vprintf(fmt, ap); /* both */ va_end(ap); return (ferror(stdout) ? EOF : nchars); } -- In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163) Domain: chris@mimsy.umd.edu Path: uunet!mimsy!chris