Mastering C++ Programming
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Template type auto-deduction for class templates

I'm sure you will love what you are about to see in the sample code.  Though templates are quite useful, a lot of people don't like it due to its tough and weird syntax. But you don't have to worry anymore; take a look at the following code snippet:

#include <iostream>
using namespace std;

template <typename T1, typename T2>
class MyClass {
private:
T1 t1;
T2 t2;
public:
MyClass( T1 t1 = T1(), T2 t2 = T2() ) { }

void printSizeOfDataTypes() {
cout << "\nSize of t1 is " << sizeof ( t1 ) << " bytes." << endl;
cout << "\nSize of t2 is " << sizeof ( t2 ) << " bytes." << endl;
}
};

int main ( ) {

//Until C++14
MyClass<int, double> obj1;
obj1.printSizeOfDataTypes( );

//New syntax in C++17
MyClass obj2( 1, 10.56 );

return 0;
}

The preceding code can be compiled and the output can be viewed with the following commands:

g++-7 main.cpp -std=c++17
./a.out

The output of the program is as follows:

Size of t1 is 4 bytes.
Size of t2 is 8 bytes.