what do i get if a cell is empty?

[Arthur 1989 <arthur19891106 gmail com>]

Hi, I met this question: I use gtk_tree_model_get(model, &iter, i, &s, -1)
to get a cell's content. but when the cell is empty,i am not sure what i
really get. i print s out with
 g_print ("s = %s\n", s) , then i get "s = (null)",so i want to test what's
in s, i run this, if (s == EXP) print("s == EXP\n"), where EXP is replaced
by "", "NULL", "null" and "(null)" ,but the test have no come out message.
can any body tell me  what is in s if i use gtk_tree_model_get() to get the
content of an empty cell. Thanks.

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Best regards