#include <string.h>

#if 0 // libnix < 3.x
size_t strspn(const char *s1,const char *s2)
{ size_t i;
  unsigned char *c1=(unsigned char *)s1;
  unsigned char *c2;
  for(i=0;;i++)
  { c2=(unsigned char *)s2;
    while(*c2!='\0'&&c1[i]!=*c2)
      c2++;
    if(*c2=='\0')
      return i;
  }
}
#else

size_t strspn(const char *s1,const char *s2)
{
  const char *s = s1;
  const char *c;
  
  while (*s1) {
    for(c = s2; *c && *s1 != *c; c++);
    if(*c == '\0')
      break;
    s1++;
  }
  
  return s1 - s;
}

#endif