Objective

Write a function that says whether the product n * size fits in a size_t, writing that product through out when it fits and leaving out alone when it does not.

Steps

• n is an element count and size is the size of one element, both size_t. out points to one size_t you are allowed to write.
• When the mathematical product of n and size is representable as a size_t, store it in *out and return 1.
• When that product is too large, return 0 and leave *out holding whatever the caller put there.
• Multiplying two size_t values never traps and is not undefined behavior: the result wraps modulo 2^64, which is well defined and wrong. SIZE_MAX * SIZE_MAX quietly evaluates to 1. So never compute n * size to find out whether n * size fits.
• Divide instead. For any n other than 0, the product is too large exactly when size > SIZE_MAX / n. SIZE_MAX comes from <stdint.h> and is 18446744073709551615 on the grading machine.
• n == 0, size == 0 and both zero at once are all valid inputs whose product is 0: write 0 and return 1. Keep your division out of the n == 0 case.
• A product equal to SIZE_MAX fits. Only a strictly larger product fails.
• The tests print your return value on one line, then *out on a second line when the return is 1. Two tests seed *out with 777 and print it either way, so an overflow that scribbles on *out is caught.

Objective

Write a function that says whether the product n * size fits in a size_t, writing that product through out when it fits and leaving out alone when it does not.

Steps

• n is an element count and size is the size of one element, both size_t. out points to one size_t you are allowed to write.
• When the mathematical product of n and size is representable as a size_t, store it in *out and return 1.
• When that product is too large, return 0 and leave *out holding whatever the caller put there.
• Multiplying two size_t values never traps and is not undefined behavior: the result wraps modulo 2^64, which is well defined and wrong. SIZE_MAX * SIZE_MAX quietly evaluates to 1. So never compute n * size to find out whether n * size fits.
• Divide instead. For any n other than 0, the product is too large exactly when size > SIZE_MAX / n. SIZE_MAX comes from <stdint.h> and is 18446744073709551615 on the grading machine.
• n == 0, size == 0 and both zero at once are all valid inputs whose product is 0: write 0 and return 1. Keep your division out of the n == 0 case.
• A product equal to SIZE_MAX fits. Only a strictly larger product fails.
• The tests print your return value on one line, then *out on a second line when the return is 1. Two tests seed *out with 777 and print it either way, so an overflow that scribbles on *out is caught.