If free() knows the length of my array, why can't I ask for it in my own code?
- by Chris Cooper
I know that it's a common convention to pass the length of dynamically allocated arrays to functions that manipulate them:
void initializeAndFree(int* anArray, int length);
int main(){
int arrayLength = 0;
scanf("%d", &arrayLength);
int* myArray = (int*)malloc(sizeof(int)*arrayLength);
initializeAndFree(myArray, arrayLength);
}
void initializeAndFree(int* anArray, int length){
int i = 0;
for (i = 0; i < length; i++) {
anArray[i] = 0;
}
free(anArray);
}
but if there's no way for me to get the length of the allocated memory from a pointer, how does free() "automagically" know what to deallocate? Why can't I get in on the magic, as a C programmer?
Where does free() get its free (har-har) knowledge from?
