custom strcmp function in c to compare two strings

#include<stdio.h>
#include<string.h>
#include<conio.h>
int mystrcmp(const char*s1,const char*s2)
{
int r=0;
while(*s1!='\0'||*s2!='\0')
{
 if(*s1!=*s2)
 {
 r=(int)(*s1-*s2);
 return r;
 }
 s1++;
 s2++;
}
return r;
}

int main()
{
  char s1[10]="Hello";
  char s2[10]="HeLlo";
  int d;
  clrscr();
  puts(s1);
  puts(s2);
  //d=strcmp(s1,s2);
  d=mystrcmp(s1,s2);
  printf("\nDiff is:%d",d);
  getch();
  return 0;
}