range -- generate loop values for the Shell
bin
bin at minster.UUCP
Thu Nov 21 09:59:30 AEST 1985
# To unbundle, sh this file
echo README >&2
cat >README << 'End of README'
Here is the command we use to
generate values for Shell loops. The syntax was intended to
match that of the Shell. Originally, it was called `from',
which might be a better name, but it later clashed with another command.
It isn't spectacular, but I thought it would be nice to see some
source in this news group for a change (hint), however short.
Exercise: extend it to allow looping through string values
End of README
echo range.1 >&2
cat >range.1 << 'End of range.1'
.TH RANGE 1 local
.SH NAME
range \- generate loop values
.SH SYNOPSIS
.BI range " n1" " to" " n2"
[
.BI by " n3"
]
.SH DESCRIPTION
.I Range
writes the numbers from
.I n1
to
.I n2
one to a line on the standard output.
The increment
.I n3
defaults to
1
.RI ( n1 \(<= n2 )
or
\-1
.RI ( n2 < n1 ).
The command is often used with the Shell
.B for
statement.
.SH EXAMPLE
Set the Shell variable
.I a
to
the strings
.I 1
to
.I 10,
with the value increasing after each
execution of the loop.
.PP
.RS
.nf
for a in \`range 1 to 10\`
do
echo $a
done
.fi
.RE
.SH SEE ALSO
apply(1), bc(1), sh(1)
.SH BUGS
There is no check for arithmetic overflow.
End of range.1
echo range.c >&2
cat >range.c << 'End of range.c'
/*
* range a to b [by c]
* generate for-loop values for Shell
*/
#include <stdio.h>
#include <ctype.h>
long atol();
void usage();
long number();
int isnumeric();
int
main(argc, argv)
char **argv;
{
register long a, b, c;
if (argc < 4 || strcmp(argv[2], "to"))
usage();
a = number(argv[1]);
b = number(argv[3]);
c = a <= b? 1: -1;
if (argc > 5) {
if (strcmp(argv[4], "by"))
usage();
c = number(argv[5]);
}
if (c < 0)
for (; a >= b; a += c)
printf("%ld\n", a);
else if (c == 0)
printf("%ld\n", a);
else
for (; a <= b; a += c)
printf("%ld\n", a);
exit(0);
}
void
usage()
{
fprintf(stderr, "Usage: range n1 to n2 [by n3]\n");
exit(1);
}
long
number(s)
char *s;
{
if (!isnumeric(s)) {
fprintf(stderr, "range: ill-formed number `%s'\n", s);
exit(1);
}
return(atol(s));
}
int
isnumeric(s)
register char *s;
{
while (*s == ' ' || *s == '\t')
s++;
if (*s == '+' || *s == '-')
s++;
do {
if (!isascii(*s) || !isdigit(*s))
return(0);
} while (*++s);
return(1);
}
End of range.c
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