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Calculating the Size of an Incomplete Array

An incomplete array declaration can appear in a function’s parameter list. For example:

   int count(const char s[]); 

The declaration of s doesn’t include the array’s size. Can count() use the operator sizeof to calculate the size of s? No, it can’t. The compiler implicitly transforms an array into a pointer. Therefore, sizeof returns a pointer’s size, not an array’s size. One way to obtain the array’s size is to pass an additional argument that holds the number of elements in the array:

   int count(const char s[], int arr_size); 

However, this solution is error prone. A better solution is to pass a vector and call its size() member function:

   int cout(const vector  &s )  {    return s.size();  }

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