/* non-recursive factorial */ #include #include void printdec(int n) { char s[16], *p; int r; p = s+16; *--p = '\n'; for(;;){ r = n%10; *--p = '0'+r; n /= 10; if(n == 0 || p == s) break; } write(1, p, s+sizeof(s)-p); } int fact(int n) { int a; a = n; repeat: if(n <= 0) return 0; else if(n == 1) return a; a *= --n; goto repeat; } void usage(void) { fprint(2, "usage: %s n\n", argv0); exits("usage"); } void main(int argc, char *argv[]) { int n; ARGBEGIN{ default: usage(); }ARGEND; if(argc != 1) usage(); n = strtol(argv[0], nil, 0); printdec(fact(n)); exits(0); }