How do I find the length of "char *" array in C?

Question

I declare the following array:

char* array [2] = { "One", "Two"};

I pass this array to a function. How can I find the length of this array in the function?

Answer 1

You can't find the length of an array after you pass it to a function without extra effort. You'll need to:

1. Use a container that stores the size, such as vector (recommended).
2. Pass the size along with it. This will probably require the least modification to your existing code and be the quickest fix.
3. Use a sentinel value, like C strings do¹. This makes finding the length of the array a linear time operation and if you forget the sentinel value your program will likely crash. This is the worst way to do it for most situations.
4. Use templating to deduct the size of the array as you pass it. You can read about it here: How does this Array Size Template Work?

¹ In case you were wondering, most people regret the fact that C strings work this way.