In C, when you pass an array as an argument to a function, what actually gets passed is the base address (pointer) of the first element of the array, not a copy of the entire array. This means the function receives a pointer to the original array's memory location, allowing it to access and modify the array elements directly. Key points explaining this behavior:
- Arrays decay to pointers when passed to functions. For example, a parameter declared as
int arr[]orint *arrin a function both mean the function receives a pointer to the first element of the array
- Although C functions always pass arguments by value, in the case of arrays, the value passed is the pointer to the first element. So effectively, the function gets the address of the array's first element
- Because the function works with the original array's address, any modifications to the array elements inside the function affect the original array outside the function
- For multidimensional arrays, the array name also decays to a pointer, but the function must know the size of all dimensions except the first to correctly calculate element addresses
This approach avoids the overhead of copying the entire array and enables efficient manipulation of array data within functions. In summary, passing an array to a function in C actually passes the pointer to the first element of the array (the base address), not the whole array itself. The function parameter acts as a pointer, allowing access to the original array elements
