以下作业是否有效？或者这些都会产生问题.请建议.
const char * c1;
const char * c2;
const char * c3;
char * c4;
c2 = c1;
c2 = c3;
c2 = c4;
如果我执行以下操作,那该怎么办呢？
const char * c5 = "xyz";
char * c6 = "abc";
c2 = c5;
c2 = c6;