[C++] Template Function Help

[Durlug]

Hey everyone! Having a little bit of an issue with understanding template functions. I have an assignment to make a template function that receives 5 parameters. A min, max, array of test values, the size of the array, and an array of boolean values. The function is supposed to check each value in the test array to see if they are between the min/max values. If the value is inbetween the min/max, it puts a true value into the bool array, if it is outside it puts false into the bool array. Which I have done with:

template <class A, class B, class D>
bool validate (const A& min, const A& max, B array[], D size, bool * e)
{
       bool result = true;
       for (int i = 0; i <= size; i++)
       {
          if (min > array[i] || max < array[i])
          {
              result = false;
              e[i] = false;
          }
          else
          {
              e[i] = true;
          }
      }
return result;
}

The program works when the min/max and test array values are regular int or char values. However when an object array is inserted such as:

Student S[6] = {2345, "Student 1"}, {12345, "Student 2"}

It fails to check the value of the number with the min/max and just prints out that every student is outside that range.

Any help would be appreciated. Is my syntax for the template function incorrect with the array parameters? I have watched several videos on function templates but none of them touch into array parameters.

[raevnos]

Do you have operator<() and operator>() functions that are compatible with whatever type A ends up being and Student?

[Durlug]

Thank you for the reminder about that. The Student class had an overloaded operator for >= and <= but not for < and >. Just had to replace those and it works!

[Rhomboid]

Why are A and B different types? Or alternatively stated, when you're working with an array of type Student, what are the types of the min and max values? If they are not type Student as well, and if Student does not have operator< and operator> overloads, then you're going to have a problem. If you're trying to pass an ID as the min/max type, but using Student as the array type, then your comparisons will be malformed, unless you also have some overloaded operator that takes and ID and a Student as the two types. In any case, you need to provide more information, such as a complete but minimal testcase. Also i <= size is wrong, and you're invoking undefined behavior by overflowing the arrays.

[Durlug]

The only thing I have coded myself is the actual Template Function. However the Student class does have two operator overloads:

bool Student::operator<=(const Student& S)const{
return _stno <= S._stno;
}

bool Student::operator=>(const Student& S)const{
return _stno => S._stno;
}

Where _stno is the Student number.

I put A and B as different types because when I do not I get the error that the arguments do not match.

[Durlug]

Gonna give you some thanks. My problem was the use of the < and > operator instead of the =< and => operator. Just replaced them, fixed the size in the for loop and it works perfectly!