How to Determine the Size of an Array Passed as a Function Argument in C ?

Array Size Determination in C Function Parameters

Unlike in the main function, determining the size of an array passed as an argument to a function in C using sizeof() requires a reference template. This is because arrays decay to pointers when passed to functions.

Array Decay to Pointers

Consider the following code snippet:

int length_of_array(int some_list[]);

Despite the declaration with square brackets, some_list decays to an integer pointer int* when passed as an argument. As a result, sizeof(some_list) returns the size of a pointer, not the array size.

Reference Template Solution

To determine the size of an array correctly, use a reference template. For example:

template<size_t n>
int length_of_array(int (&arr)[N]) {
  std::cout <p><strong>Exception: Multidimensional Arrays</strong></p>
<p>There is one exception to the array decay rule. Multidimensional arrays retain their dimensionality and are not passed as pointers. Hence, sizeof() can be used directly to determine their size:</p>
<pre class="brush:php;toolbar:false">int a[3][4];
std::cout 

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