strcpack.c

Many C samples. It is a good sample for students to learn C language.

/*  File   : strcpack.c
    Author : Richard A. O'Keefe.
    Updated: 20 April 1984
    Defines: strcpack()

    strcpack(dst, src, set, c)
    copies characters from src to dst, stopping when it finds a NUL.  If
    c is NUL, characters not in the set are not copied to dst.  If c  is
    not  NUL,  sequences  of  characters  not in the set are copied as a
    single c. strcpack is to strpack as strcspn is to strspn.  If your C
    compiler is happy with register _char_, change the declaration of c.
    The result is the address of the NUL byte that now terminates "dst".
    Note that dst may safely be the same as src.
*/

#include "strings.h"
#include "_str2set.h"

char *strcpack(dst, src, set, c)
    register _char_ *dst, *src;
    char *set;
    register int c;
    {
	register int chr;

	_str2set(set);
	while (chr = *src++) {
	    if (_set_vec[chr] != _set_ctr) {
		while ((chr = *src++) && _set_vec[chr] != _set_ctr) ;
		if (c) *dst++ = c;	/* 1. If you don't want trailing */
		if (!chr) break;	/* 2. things turned into "c", swap */
	    }				/* lines 1 and 2. */
	    *dst++ = chr;
	}
	*dst = 0;
	return dst;
    }