c语言学习strcopy

自己写了一个字符串复制函数：

   #include<stdio.h>
   #include<assert.h>
   char *mystrcpy(char *des,char *ser)
           {
             assert((des!=NULL)&&(ser!=NULL));
             char *adress=des;
             int num=;
             while(*ser!='\0')
               {
                  *des++=*ser++;
                  num++;
              }
            printf("data:%d\n",num);
            return adress;
  }
  int main()
          {
            char a[]="hello qiuheng\n";
            char b[]="aaaaa";
            int *e=NULL;
            char *p,*q;
            p=a;
            q=b;
            mystrcpy(q,p);
            printf("character:%s",q);
            //printf("num:%d\n",e);
            return ;
  }