delete

static VALUE
fsdbm_delete(VALUE obj, VALUE keystr)
{
    datum key, value;
    struct dbmdata *dbmp;
    DBM *dbm;
    VALUE valstr;

    fdbm_modify(obj);
    ExportStringValue(keystr);
    key.dptr = RSTRING_PTR(keystr);
    key.dsize = RSTRING_LENINT(keystr);

    GetDBM2(obj, dbmp, dbm);
    dbmp->di_size = -1;

    value = sdbm_fetch(dbm, key);
    if (value.dptr == 0) {
        if (rb_block_given_p()) return rb_yield(keystr);
        return Qnil;
    }

    /* need to save value before sdbm_delete() */
    valstr = rb_external_str_new(value.dptr, value.dsize);

    if (sdbm_delete(dbm, key)) {
        dbmp->di_size = -1;
        rb_raise(rb_eDBMError, "dbm_delete failed");
    }
    else if (dbmp->di_size >= 0) {
        dbmp->di_size--;
    }
    return valstr;
}