(3)连接运算 strconcat(S1S2 seqstring x strconcat(seqstring Sl, seqstring $2) i int i; seqstring x if (sIlength+S2.length>MAXSIZE) &( cannot concat"); return(NULL); else dr(seqstring )malloc(sizeof(seqstring)); for (i=0; i<SIlength; i++)r>str= sIstril; for(i=0; i<S2. length; i++) r->strI SIlength+il= S2.stril; r->length= SIlength+ s2.length r->str[r-length=0; return(r（3）连接运算strconcat(S1 ,S2 ) seqstring * strconcat(seqstring S1,seqstring S2) { int i; seqstring *r; if (S1.length+S2.length>MAXSIZE) { printf("cannot concate"); return(NULL);} else { r=(seqstring*)malloc (sizeof(seqstring)); for (i=0; i<S1.length;i++) r->str[i]= S1.str[i]; for (i=0; i<S2.length;i++) r->str[ S1.length+i]= S2.str[i]; r->length= S1.length+ S2.length; r->str[r->length]='\0'; } return (r); }