字符数组归并排序操作

两个排序好的字符数组，归并排序依然得到有序字符数组数组

char * cmp(char* s1,char* s2)
  {
      char *s= (char*)malloc(sizeof(char*)*20);
      char *ss=s;
        assert(s1);
        assert(s2);
 
        while(*s1!='\0'&&*s2!='\0')
        {
             if(*s1>=*s2)
             {
                *s=*s1;
                 s1++;
                 s++;
             }
             else
             {
                 *s=*s2;
                 s2++;
                 s++;
             }
        }
        if(*s1=='\0')
        {
             
             while(*s2!='\0')
             {
                 *s++=*s2++;
             }
        }
        else
        {
             
             while(*s1!='\0')
             {
                 *s++=*s1++;
             }
        }
        *s='\0';  //注意结束字符的写法
        returnss;
  }
 

char* str1="ca";

char*str2="db";

cout<