Both sharks and crocodiles are apex ambush predators, so it is likely that the winner in a combat situation is the one that strikes first. Sharks and crocodiles do not usually hunt and kill each other. However, there are rare instances of crocodiles and sharks killing and eating each other.
Sharks and crocodiles have territory ranges that are different, and they each hunt different sources of prey.
Both animals can grow up to 20 feet long and have an impressive bite. The bite of the crocodile is much stronger than that of a shark, but it also has to breathe, which is a major disadvantage in aquatic combat.
The size disparity between predator and prey would also play a large factor in determining the winner of an encounter. Animal Planet declares that in a fight between a crocodile and a great white, the great white shark would be the winner.