How Can I Determine the Size of an Array Passed to a C Function?

Determining Array Size Passed to C Function

In order to ascertain the size of an array passed to a C function, it is crucial to understand the fundamental behavior of arrays as function parameters. Arrays, when employed as function parameters, degenerate into pointers. Consequently, the sizeof operator becomes ineffectual in determining the array's true size.

Erroneous Approach in the Code

The code snippet provided employs sizeof(p_vertData) in an attempt to retrieve the array's size. However, this approach is flawed. The array p_vertData degrades to a pointer upon being passed to the makeVectorData function. The sizeof operator subsequently returns the size of the pointer, not the size of the array.

Correct Method

Regrettably, there is no foolproof method to ascertain the size of an array passed as a parameter to a C function. The array's size must be explicitly transmitted as an additional parameter to the function.

Revised Code

void makeVectorData(float p_vertData[], int size) {
  // Use the provided size to work with the array
}

This revised code remedies the issue by incorporating an additional parameter, size, which explicitly conveys the array's size to the makeVectorData function.

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