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Class Templates in C++ Programming Language
Class Templates in C++
Templates are powerful features of C++ which allows us to write generic programs. Similar to function templates, we can use class templates to create a single class to work with different data types. Class templates come in handy as they can make our code shorter and more manageable. A class template starts with the keyword template followed by template parameter(s) inside <> which is followed by the class declaration.
Declaration for Class Template in C++
template <class T>
class className {
private:
T var;
... .. ...
public:
T functionName(T arg);
... .. ...
};
T
template argument
var
a member variable
T is the template argument which is a placeholder for the data type used, and class is a keyword.
Inside the class body, a member variable var and a member function functionName() are both of type T.
Creating a class template object:
Once we've declared and defined a class template, we can create its objects in other classes or functions (such as the main() function) with the following syntax:
className<dataType> classObject;
template <class T>
class ClassName {
... .. ...
// Function prototype
returnType functionName();
};
// Function definition
template <class T>
returnType ClassName<T>::functionName() {
// code
}
template <class T, class U, class V = int>
class ClassName {
private:
T member1;
U member2;
V member3;
... .. ...
public:
... .. ...
};
/* Templates are the foundation of generic programming, which involves writing code in a way that is independent of any particular type. A template is a blueprint or formula for creating a generic class or a function. */
#include <iostream>
using namespace std;
template <typename T>
class Array {
private:
T *ptr;
int size;
public:
Array(T arr[], int s);
void print();
};
template <typename T>
Array<T>::Array(T arr[], int s) {
ptr = new T[s];
size = s;
for(int i = 0; i < size; i++)
ptr[i] = arr[i];
}
template <typename T>
void Array<T>::print() {
for (int i = 0; i < size; i++)
cout<<" "<<*(ptr + i);
cout<<endl;
}
int main() {
int arr[5] = {1, 2, 3, 4, 5};
Array<int> a(arr, 5);
a.print();
return 0;
}
Rows of "Pascal's Triangle" are conventionally enumerated starting with row n = 0 at the top ('0th row'). Entries in each row are numbered from the left beginning with k=0 & are usually
