c - need to write a function that takes a string an integer offset and size and prints starting from offset and upto offset+size the string -

the idea trim string starting value of offset , upto value of size , return along new string return 1; , if gets outside of code boundery return 0 . code:

int subprint(char *s, int offset,int size){     char *m;     m = (s + offset);     while(size != 0){      m = (m + 1);     if(m == '\0')         return 0;     size--;   }  s = m; return 1;  }  void subprinttest(){      char s[20] = "industrial";      subprint(s,2,4);      printf("%s",s);  }  void main(){      subprinttest();      getch();  } 

the problem printing original string s unchanged

the issue having pointer s being passed value function subprint. in order intend, pass pointer pointer s.

reference: is passing pointer argument, pass value in c++?