重载的模板功能帮助-C ++

Question

I keep getting an error "no instance of overloaded function "printArray" matches the argument list. Will someone please tell me why? I'm trying to overload a template function so that it displays elements of an array starting and ending at specified positions.

I have my initial template and function:

template< typename T >
void printArray( const T *array, int count )

And the function that I'm trying to overload.

template< typename T >
void printArray(int lowSubscript, int highSubscript)

and my call:

// display elements 1-3 of array a
   cout << "Array a from positions 1 to 3 is:\n";
   elements = printArray(1,3);

my call for the first printArray shows no errors:

// display array a using original printArray function
   cout << "\nUsing original printArray function\n";
   printArray( a, ACOUNT );

Answer 1

Your second overload of printArray is a template, but the signature is not dependent on the template parameter T . Therefore you must specify it when calling, eg printArray<int>(1,3) .

However, it is unclear which array is being printed: did you forget to add a parameter for the array, eg printArray(a,1,3) ? In which case, you might be able to have T deduced from that parameter, as it is in the printArray(a,count) version.

Also, the return type of void means you cannot write elements=printArray(1,3) even if the template parameter could be deduced.

Answer 2

Your second printArray does not use T, and thus should not be a template.

The reason the compiler does not recognize it as a candidate is because it can not deduce T.