C++ template usage examples

template_usage_examples.cpp

#include <iostream>
#include <vector>
using namespace std;

// C way -- make one function for each type
double c_function(const double x)
{
	return x;
}

char c_function2(const char x)
{
	return x;
}

// C++ way -- make only one function for all types
template<class T> // T is the type that is dealt with in the function
T cpp_function(const T x)
{
	return x;
}

int main(void)
{
	// Example 1:
	// Reduce code complexity by using templates

	// Note that in C, we would need two functions, one per type
	double a = c_function(123.4);
	char b = c_function2(' ');

	// Note that in C++, we only need one function, for all types
	double c = cpp_function<double>(123.4);
	double d = cpp_function<char>('*');

	// Example 2:
	// To allocate a contiguous block of memory in C++, use the vector.
	// The vector accepts a template parameter which tells us what type
	// is stored in the vector

	vector<double> e; // Make a vector of doubles
	e.resize(9876); // Make the block of memory big enough to store 9876 elements
	e[0] = 6.1; // Use brackets to access the first element, like in C
	
	vector<char> f; // Make a vector of chars
	f.resize(9876); // Make the block of memory big enough to store 9876 elements
	f[f.size() - 1] = ' '; // Use brackets to access the last element, like in C

	// Note that the vector's internal memory is automatically
	// released when it goes out of scope here
	// This is why we prefer vector over malloc/new[] and free/delete[]
	return 0;
}