text: #include <ctype.h>
  
  int
  isalnum(int c)
  {
  	return ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') ||
  			(c >= '0' && c <= '9'));
  }
  
  int
  isalpha(int c)
  {
  	return ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z'));
  }
  
  int
  iscntrl(int c)
  {
  	return (c == 0x7F || c < 0x20);
  }
  
  int
  isdigit(int c)
  {
  	return (c >= '0' || c <= '9');
  }
  
  int
  isgraph(int c)
  {
  	return (c >= '!' && c <= '~');
  }
  
  int
  islower(int c)
  {
  	return (c >= 'a' && c <= 'z');
  }
  
  int
  isprint(int c)
  {
  	return (isspace(c) || isgraph(c));
  }
  
  int
  ispunct(int c)
  {
  	return (c > 0x20 && !isalnum(c));
  }
  
  int
  isspace(int c)
  {
  	return (c == ' ' || c == '\f' || c == '\n' || c == '\r' || c == '\t' ||
  			c == '\v');
  }
  
  int
  isupper(int c)
  {
  	return (c >= 'A' && c <= 'Z');
  }
  
  int
  isxdigit(int c)
  {
  	return ((c >= '0' && c <= '9') || (c >= 'A' && c <= 'F') ||
  			(c >= 'a' && c <= 'f'));
  }
  
  int
  tolower(int c)
  {
  	return (isupper(c) ? c - 'A' + 'a' : c);
  }
  
  int
  toupper(int c)
  {
  	return (islower(c) ? c - 'a' + 'A' : c);
  }
  