array.reject! {|item| block }  → array or nil

Equivalent to Array#delete_if, deleting elements from self for which the block evaluates to true, but returns nil if no changes were made. Also see Enumerable#reject.

Source Code

/*
*  call-seq:
*     array.reject! {|item| block }  -> array or nil
*  
*  Equivalent to <code>Array#delete_if</code>, deleting elements from
*  _self_ for which the block evaluates to true, but returns
*  <code>nil</code> if no changes were made. Also see
*  <code>Enumerable#reject</code>.
*/

static VALUE
rb_ary_reject_bang(ary)
   VALUE ary;
{
   long i1, i2;

   rb_ary_modify(ary);
   for (i1 = i2 = 0; i1 < RARRAY(ary)->len; i1++) {
       VALUE v = RARRAY(ary)->ptr[i1];
       if (RTEST(rb_yield(v))) continue;
       if (i1 != i2) {
           rb_ary_store(ary, i2, v);
       }
       i2++;
   }
   if (RARRAY(ary)->len == i2) return Qnil;
   if (i2 < RARRAY(ary)->len)
       RARRAY(ary)->len = i2;

   return ary;
}