char is really a byte (so, an 8 bit integer). So, you can simply do this:
1 2 3 4 5
char number[] = "54465465445646848640";
int size = sizeof(number) / sizeof(char) - 1; // Total chars in the array, -1 because your string has an invisible \0.
std::vector<int> result(size); // Initialize a result vector with size equal to your array's
for (int i = 0; i < size; ++i)
result[i] = number[i];
Good luck
ps: If you want the integer values that are equal to the numbers in the string, subtract them by 48 (= the character code of '0')