Example
The basic idea of a class template is that the template parameter gets substituted by a type at compile time. The result is that the same class can be reused for multiple types. The user specifies which type will be used when a variable of the class is declared. Three examples of this are shown in main():
#include <iostream>
using std::cout;
template <typename T> // A simple class to hold one number of any type
class Number {
public:
void setNum(T n); // Sets the class field to the given number
T plus1() const; // returns class field's "follower"
private:
T num; // Class field
};
template <typename T> // Set the class field to the given number
void Number<T>::setNum(T n) {
num = n;
}
template <typename T> // returns class field's "follower"
T Number<T>::plus1() const {
return num + 1;
}
int main() {
Number<int> anInt; // Test with an integer (int replaces T in the class)
anInt.setNum(1);
cout << "My integer + 1 is " << anInt.plus1() << "\n"; // Prints 2
Number<double> aDouble; // Test with a double
aDouble.setNum(3.1415926535897);
cout << "My double + 1 is " << aDouble.plus1() << "\n"; // Prints 4.14159
Number<float> aFloat; // Test with a float
aFloat.setNum(1.4);
cout << "My float + 1 is " << aFloat.plus1() << "\n"; // Prints 2.4
return 0; // Successful completion
}
