I have many questions about this starter code about C not C++. sprintf(valueString, "", value); is it ok if """ is empty?

I have many questions about this starter code about C not C++.

1. sprintf(valueString, "", value); is it ok if """ is empty?
2. the function void populateDeck() in poke.c,

it says " Using createCard() from card.c, create cards corresponding to the 52 standard playing cards and add them to the deck[] array. You might put code in main() to print out all 52 cards in deck[] using displayCard(), to confirm that you wrote populateDeck() correctly." I have no idea how to do this part.