Thankfully there is a C language group!
Hello!
I am a hobyist who is rediscovering writing C programs on Linux. I
use GCC and I am at a loss as to why the compile fails to find the
following:
Start---
gcc -o gexpr gexpr.c
/tmp/ccbsDbYK.o: In function `term':
/tmp/ccbsDbYK.o(.text+0x172): undefined reference to `fmod'
/tmp/ccbsDbYK.o: In function `expo':
/tmp/ccbsDbYK.o(.text+0x1bf): undefined reference to `pow'
/tmp/ccbsDbYK.o: In function `log2':
/tmp/ccbsDbYK.o(.text+0x1f6): undefined reference to `log'
/tmp/ccbsDbYK.o: In function `factor':
/tmp/ccbsDbYK.o(.text+0x336): undefined reference to `floor'
/tmp/ccbsDbYK.o: In function `main':
End---
ETC....
I'm sure it's me and what I am doing so would you be kind enough to
point out what I am doing wrong in compiling. I use a simple call of
"gcc -o gexpr gexpr.c"
It's been a long time since I wrote programs and I need some help.
Ernst
The Program is as follows
Start---
/* Expression evaluation using plain floating-point arithmetic.
Copyright (C) 1999, 2000, 2001, 2002, 2003 Free Software
Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under
the terms of the GNU General Public License as published by the Free
Software
Foundation; either version 2, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A
PARTICULAR PURPOSE. See the GNU General Public License for more
details.
You should have received a copy of the GNU General Public License
along with
this program; see the file COPYING. If not, write to the Free
Software
Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include <string.h>
#include <stdio.h>
#include <setjmp.h>
#include <math.h>
jmp_buf top;
static char *bp, *expr_start_p, *expr_end_p;
static int ch;
static int previous_result_valid_flag;
double previous_result;
double floor (), strtod ();
double term (), expo (), factor (), number ();
#define next skip ()
void
skip ()
{
do
ch = *bp++;
while (ch == ' ' || ch == '\n');
}
void
error ()
{
fprintf (stderr, " ^ syntax error\n");
longjmp (top, 1);
}
double
expr ()
{
double e;
if (ch == '+')
{
next;
e = term ();
}
else if (ch == '-')
{
next;
e = - term ();
}
else
e = term ();
while (ch == '+' || ch == '-')
{ char op;
op = ch;
next;
if (op == '-')
e -= term ();
else
e += term ();
}
return e;
}
double
term ()
{
double t;
t = expo ();
for (;;)
switch (ch)
{
case '*':
next;
t *= expo ();
break;
case '/':
next;
t /= expo ();
break;
case '%':
next;
t = fmod (t, expo ());
break;
default:
return t;
}
}
double
expo ()
{
double e;
e = factor ();
if (ch == '^')
{
next;
e = pow (e, expo ());
}
return e;
}
struct functions
{
char *spelling;
double (* evalfn) ();
};
double
log2 (x)
double x;
{
return log (x) * 1.4426950408889634073599246810019;
}
struct functions fns[] =
{
{"log2", log2},
{"log10", log10},
{"log", log},
{"exp", exp},
{"sqrt", sqrt},
{"floor", floor},
{"ceil", ceil},
{"sin", sin},
{"cos", cos},
{"tan", tan},
{"asin", asin},
{"acos", acos},
{"atan", atan},
{"sinh", sinh},
{"cosh", cosh},
{"tanh", tanh},
{"asinh", asinh},
{"acosh", acosh},
{"atanh", atanh},
{0, 0}
};
double
factor ()
{
double f;
int i;
for (i = 0; fns[i].spelling != 0; i++)
{
char *spelling = fns[i].spelling;
int len = strlen (spelling);
if (strncmp (spelling, bp - 1, len) == 0 && ! isalnum (bp[-1 +
len]))
{
bp += len - 1;
next;
if (ch != '(')
error ();
next;
f = expr ();
if (ch != ')')
error ();
next;
return (fns[i].evalfn) (f);
}
}
if (ch == '(')
{
next;
f = expr ();
if (ch == ')')
next;
else
error ();
}
else
f = number ();
if (ch == '!')
{
unsigned long n;
if (floor (f) != f)
error ();
for (n = f, f = 1; n > 1; n--)
f *= n;
next;
}
return f;
}
double
number ()
{
double n;
char *endp;
if (strncmp ("pi", bp - 1, 2) == 0 && ! isalnum (bp[1]))
{
bp += 2 - 1;
next;
return 3.1415926535897932384626433832795;
}
if (ch == '$')
{
if (! previous_result_valid_flag)
error ();
next;
return previous_result;
}
if (ch != '.' && (ch < '0' || ch > '9'))
error ();
n = strtod (bp - 1, &endp);
if (endp == bp - 1)
error ();
bp = endp;
next;
return n;
}
main (argc, argv)
int argc;
char **argv;
{
int nl_flag = 1;
int hhmm_flag = 0;
int dhhmm_flag = 0;
int round_flag = 0;
int prec = 5;
while (argc >= 2)
{
if (!strcmp (argv[1], "-n"))
{
nl_flag = 0;
argv++;
argc--;
}
else if (!strcmp (argv[1], "-hhmm"))
{
hhmm_flag = 1;
argv++;
argc--;
}
else if (!strcmp (argv[1], "-dhhmm"))
{
dhhmm_flag = 1;
argv++;
argc--;
}
else if (!strcmp (argv[1], "-round"))
{
round_flag = 1;
argv++;
argc--;
}
else if (!strcmp (argv[1], "-prec"))
{
prec = atoi (argv[2]);
argv += 2;
argc -= 2;
}
else if (!strcmp (argv[1], "-help") || !strcmp (argv[1], "-h"))
{
printf ("usage: %s [options] expr [expr ... ]\n", argv[0]);
printf (" options: -n -- suppress newline\n");
printf (" -prec n -- print n digits\n");
printf (" -round -- round to nearesr integer\n");
printf (" -hhmm -- print in base 60 (time
format)\n");
printf (" -dhhmm -- print in base 24,60,60 (time
format)\n");
printf (" -help -- make demons drop from your
nose\n");
exit (0);
}
else
break;
}
if (argc >= 2)
{
int i;
double exp;
for (i = 1; i < argc; i++)
{
expr_start_p = argv[i];
expr_end_p = expr_end_p + strlen (expr_start_p);
bp = expr_start_p;
next;
if (setjmp (top) == 0)
{
int h, m;
exp = expr ();
if (round_flag)
exp = floor (exp + 0.5);
if (hhmm_flag)
{
h = (int) floor (exp);
m = (int) ((exp - floor (exp)) * 60.0 + 0.5);
h += m / 60; m = m % 60;
printf ("%02d:%02d", h, m);
}
else if (dhhmm_flag)
{
double tmp = (exp - floor (exp)) * 24.0;
h = (int) floor (tmp);
m = (int) ((tmp - floor (tmp)) * 60.0 + 0.5);
h += m / 60; m = m % 60;
printf ("%dd %02d:%02d", (int) floor (exp), h, m);
}
else
printf ("%.*g", prec, exp);
if (nl_flag)
puts ("");
previous_result = exp;
previous_result_valid_flag = 1;
}
}
}
else
{
#define BUFSIZE 1024
char buf[BUFSIZE];
double exp;
for (;;)
{
fputs ("eval> ", stdout);
bp = fgets (buf, BUFSIZE, stdin);
if (bp == NULL)
break;
next;
if (setjmp (top) == 0)
{
int h, m;
exp = expr ();
if (round_flag)
exp = floor (exp + 0.5);
if (hhmm_flag)
{
h = (int) floor (exp);
m = (int) ((exp - floor (exp)) * 60.0 + 0.5);
h += m / 60; m = m % 60;
printf ("%02d:%02d", h, m);
}
else if (dhhmm_flag)
{
double tmp = (exp - floor (exp)) * 24.0;
h = (int) floor (tmp);
m = (int) ((tmp - floor (tmp)) * 60.0 + 0.5);
h += m / 60; m = m % 60;
printf ("%dd %02d:%02d", (int) floor (exp), h, m);
}
else
printf ("%.*g", prec, exp);
if (nl_flag)
puts ("");
previous_result = exp;
previous_result_valid_flag = 1;
}
}
}
exit (0);
}
End----
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Ernst_Berg
ram_nrk2000
markmcintyre
29488 articles. 
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