How to create a function to get the size of an array in C? Function and array aren't from the same scope. for example:
int func(int arr[]);
int main(){
int arr[5];
}
int arr_length(int arr[]){
int length = sizeof(arr)/sizeof(int);
return length;
}
The problem with the function above that it treats arr as a pointer so it has the size of a pointer
simply pass the array length along with the pointer to the array in the arguments, this is pretty common
int some_func(int arr[], int n);
Or create a more sophisticated structure for arrays in your application:
typedef struct {
int *vector;
int length;
int capacity;
} Array;
you can also use my implementations: https://gist.github.com/arianito/57e668790b723a6e6649d4535e9dcaae
malloc_usable_size queries the OS for the amount of memory it has allocated from a previous call to malloc. (Meaning it will be slow, and pointless, because you didn't already cache that information, even though you at some point had it when you called malloc.)
int for length and capacity. At the time of writing, I'd still wager a fiver on the conjecture that the majority of C programs currently running have a 16 bit int.
int arr_length(int arr[])).
arr_length, thearrparameter is a pointer. In C, the way is to pass the length along with the pointer:int arr_length(int arr[], size_t arr_size) { return arr_size; }int func(int arr[]);is really the same asint func(int *arr);malloc_usable_size, or other things that are only for dynamically allocated memory. If not, what platform provides a way forfuncto get the size associated with itsarrparameter when the caller definedint a[3][5]and passeda[1]?size_tparameter?intcannot portably represent all possible sizes.