swapcase()
  public
  
    
    
Returns a copy of str with uppercase alphabetic characters
converted to lowercase and lowercase characters converted to uppercase.
Note: case conversion is effective only in ASCII region.
"Hello".swapcase          
"cYbEr_PuNk11".swapcase   
   
  
    Show source    
    
      static VALUE
rb_str_swapcase(VALUE str)
{
    str = rb_str_dup(str);
    rb_str_swapcase_bang(str);
    return str;
}