C++ Adding 2 arrays together quickly

Question

Given the arrays:

int canvas[10][10];
int addon[10][10];

Where all the values range from 0 - 100, what is the fastest way in C++ to add

Answer 1

Here is an alternative.

If you are 100% certain that all your values are between 0 and 100, you could change your type from an int to a uint8_t. Then, you could add 4 elements together at once of them together using uint32_t without worrying about overflow.

That is ...

uint8_t  array1[10][10];
uint8_t  array2[10][10];
uint8_t  dest[10][10];
uint32_t *pArr1 = (uint32_t *) &array1[0][0];
uint32_t *pArr2 = (uint32_t *) &array2[0][0];
uint32_t *pDest = (uint32_t *) &dest[0][0];

int  i;

for (i = 0; i < sizeof (dest) / sizeof (uint32_t); i++) {
    pDest[i] = pArr1[i] + pArr2[i];
}

It may not be the most elegant, but it could help keep you from going to architecture specific code. Additionally, if you were to do this, I would strongly recommend you comment what you are doing and why.