Category : Files from Magazines
Archive   : CGAZV3N3.ZIP
Filename : TENKEY.C

/****** read10key **************************************************
* Purpose: accept a numeric field entry from right to left,
* displaying commas and decimal point as data is entered.
* It returns exit key, or zero if field is full
*
* Author: Hannah Lindt
*
* Usage: declare as: int read10key(long *, int);
* invoke as: length=read10key(&value, maxwidth);
* Sample usage given in test driver
*
* Limits: The routine works with the value in pennies (i.e., *100),
* and stores this in a long. The
* largest value it can accommodate is $21,474,836.47.
*
* Compilers: verified for TurboC 2.0, MSC 5.1,
* DeSmet 3.03 (uses pcio.a routines)
* Memory models: all
* Compile time switches:
* DEBUG compiles in a test driver
* __DESMET__ compiles for DeSmet
*
* Source code may be freely used if source is acknowledged.
* Object code may be freely used.
******************************************************************/

# define DEBUG

# ifdef __DESMET__ /* use macros to access DeSmet equivalents */
# define getch ci
# define putch scr_co
int ci();
void scr_co();
# else /* Turbo C and MSC */
# include
# endif

# include

# define SPACE ' ' /* space char */
# define BELL '\7' /* the bell for errors */
# define BS '\b' /* backspace */
# define Delete 83 /* the main byte, aux byte sequence 0,83
means we saw the "del" key */
# define MAXSTR 30 /* maximum size of input string. It must allow
for the max width of the input field,
including commas and decimal point. */

# ifdef __DESMET__
int ltodec();
# else
int ltodec(long, char*, int); /* display converter */
#endif

int read10key(value, width)
long *value; /* result -- also contains initial value */
int width;
{
char str[MAXSTR], /* display work area */
*s; /* work pointer */
int pad, /* number of leading blanks */
len, /* current len of str */
i, /* counter */
negative = 0, /* hold sign of result */
ch, ch_aux; /* character read */

while(1)
{
len = ltodec(*value, str, negative); /* format str */
pad = width - len; /* number of pad spaces */
while(pad-- > 0) /* pad with */
putch(SPACE); /* spaces */
for (s=str; *s; s++) /* write string */
putch(*s);
if(len >= width) /* if field full */
return 0;
ch = getch(); /* get char */
if (ch == 0) /* start of a main byte, aux byte seq */
ch_aux = getch(); /* get aux byte */

if(isdigit(ch)) {
*value = *value * 10 + (ch - '0'); /* accum val */
if (*value < 0) { /* oops - too big! */
*value = 0;
putch(BELL); /* ring the bell */
}
}
else if (ch == '-')
negative = !negative; /* change sign */
else if (ch == BS)
*value /= 10; /* strip off a digit */
else if (ch == 0 && ch_aux == Delete) {
*value = 0; /* clear whole entry */
negative = 0;
}
else {
if (negative)
*value = -*value; /* set sign of return value */
return ch; /* return terminating character */
}

for (i=0; i putch(BS);
}

}

/*
** ltodec -- convert long to comma and period separated decimal string
**
** returns length of string
*/

int ltodec(val, str, negative)
long val; /* value to be converted */
char *str; /* location to store string */
int negative; /* is 1 if value is negative */
{
char digs[MAXSTR+1],/* string representation of val */
*f = digs, /* work */
*t = digs, /* ptrs */
sep = '.'; /* separator */
int dlen = 0, /* length of digs string */
flen, /* length of str string */
sdig; /* separator digit count */

while( val )
{ /* convert val */
*t++ = ( val % 10 ) + '0'; /* to string */
val /= 10; /* in reverse order */
}

for( dlen = t - digs; dlen < 3; dlen++ ) /* if less than 3 digits */
*t++ = '0'; /* pad with zeroes */

flen = dlen + (dlen / 3) + negative;
t = str + flen; /* point to end of string */
*t-- = 0; /* terminate string */
for(sdig = 1; dlen; dlen--, sdig++)
{ /* while there are digits */
if(sdig == 3)
{ /* every 3rd digit */
*t-- = sep; /* put in separator */
sdig = 0; /* reset count */
sep = ','; /* easier than test */
}
*t-- = *f++; /* xfer digit */
}
if (negative) /* check flag */
*t-- = '-';

return flen; /* string width */
}


# ifdef DEBUG

# include

main()
{
long val = 0;

# ifdef __TURBOC__
directvideo = 1;
# endif

fputs("\nenter value ==> ", stdout);
read10key(&val, 15); /* a width of 15 allows for values in the range
-$21,474,836.47 to $21,474,836.47. These are
the max & min values the routine will handle */

printf("\nValue entered was %ld\n", val);

}

# endif