SPI_????

I want to ask a question that it may look totally stupid but i have stacked as
a new user of postgresql!!!

I want to take the result of a sql question of the general type "select
att0 ..." where att0 is text and to store it to a C variable of char *. I
have read that there is the SPI_exec that returns a number of the returned
tupels of the question - if the result of my question is the SPI_getvalue
could anyone show me a small example how to use it -if it's something
else i would appreciate your advice .Thanks a priori.

SWTHRHS TOYRTOYNHS
(tourtoun(at)csd(dot)uch(dot)gr)