18-Dec-85 20:39:55-MST,1483;000000000001
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From: Liudvikas Bukys <
[email protected]>
Newsgroups: net.sources
Subject: phone_gen -- a simple efficient general phone number letterizer
Message-ID: <
[email protected]>
Date: 18 Dec 85 17:36:54 GMT
Keywords: telephone number permutation
To:
[email protected]
Here is a little program which does just what the recently-posted
"telno" program does, except that it is more general (no restrictions
on phone number format, no compiled-in array sizes), more efficient
(no big arrays, no calls to qsort()), and a lot simpler.
-------
/*
* generate all alphabetic strings corresponding to a phone number
*
* n.b.: assumes I can modify argv[][] in place!
*/
int main(argc, argv)
int argc;
char **argv;
{
for (; --argc > 0; printf("\n"))
phone_gen(*++argv, 0);
return (0);
}
char *table[] = { "abc", "def", "ghi", "jkl", "mno", "prs", "tuv", "wxy" };
phone_gen(s, i)
char *s;
int i;
{
char c, *s2;
c = s[i];
if (c == '\0')
printf("%s\n", s);
else if ('2' <= c && c <= '9')
for (s2= table[c-'2']; s[i]= *s2++;)
phone_gen(s, i+1);
else
phone_gen(s, i+1);
s[i] = c;
}
-------
I guess it also assumes that the characters '2' through '9' are
contiguous in your character set.
