template

[BilJ0]

In vc++, If I comment out the lines in main, any error such as an extra letter in definition of "void array<T>::setArray", is ignored
by the compiler/linker. why?.

int main() 
{
array< int > int_array(5);
int_array.setArray(0,1);
return 0;
}

#ifndef ARRAY_H_
#define ARRAY_H_

template< class T > class array {
private:
        int size;
        T *arrayA;
public:
        array (int s) {
        sz = s;
        arrayA = new T [sz];
        }

void setArray ( int index, T val);

};

template< class T >
void array<T>::setArray ( int index, T val) {
        arrayA[index] = val; 
        }

#endif

[Lindley]

First, be aware that there is a std::array class which your class may conflict with. (Although that's a fixed-size array; you seem to be attempting to create a dynamic array class more similar to std::vector.)

To answer your question, compilers are not required to do anything at all with templates that are not instantiated. They may not be able to detect syntax errors in that case.

[Paul McKenzie]

Why is your main() program defined before the template?

Regards,

Paul McKenzie

[PredicateNormative]

In vc++, If I comment out the lines in main, any error such as an extra letter in definition of "void array<T>::setArray", is ignored
by the compiler/linker. why?.

int main() 
{
array< int > int_array(5);
int_array.setArray(0,1);
return 0;
}

#ifndef ARRAY_H_
#define ARRAY_H_

template< class T > class array {
private:
        int size;
        T *arrayA;
public:
        array (int s) {
        sz = s;
        arrayA = new T [sz];
        }

void setArray ( int index, T val);

};

template< class T >
void array<T>::setArray ( int index, T val) {
        arrayA[index] = val; 
        }

#endif

There are sometimes good reasons to do it, but these are rare occasions. So, here is my question... why are you trying to implement a vector like container class when you already have std::vector at you finger tips? Is it a learning exercise? If so, you can potentially learn quite a lot. If not, are you sure you really need to do it?