C++ Inline Functions and Recursion

Inline Functions

C++ inline function is very useful concept that is commonly used with classes. If a function is inline, the compiler places a copy of the code of that function at each point where the function is called at compile time.

Basically an inline function code is re-written wherever the function call is encountered.


#include 
 
using namespace std;

inline int greater(int x, int y) {
   return (x > y)? x : y;
}

// Main function for the program
int main() {
   cout << "Max (20,10): " << greater(20,10) << endl;
   cout << "Max (0,200): " << greater(0,200) << endl;
   cout << "Max (100,1010): " << greater(100,1010) << endl;
   
   return 0;
}


Output:
Max (20,10): 20
Max (0,200): 200
Max (100,1010): 1010

Recursion

When function is called within the same function, it is known as recursion in C++. Using recursive algorithm, certain problems can be solved quite easily.

Consider a situation where we have to determine the factorial of first n natural numbers. Lets try to write a program for the same.

Factorial of number is basically the product of the number and product of all numbers preceding the number. So factorial of 6 will be 1*2*3*4*5*6=720

To perform this we can use a do while loop.


#inclide
using namespace std;
main()
{
	int n;
	int factorial=1;
	cout<<"enter the number:";
	cin>>n;
	do
	{ 
		factorial=factorial*n;//multiplying n and n-1
		n--;//decrementing n by 1
		}while(n!=0);
	cout<<"\nfactorial:"<


Output:
enter the number:6
factorial:720

We can perform the same operation using a recursive function.

Looking at the above flow chart we can write a recursive function using the given syntax


void exampleRecursive()
{
	.......
	condition true{
	exampleRecursive;
	}
	return ;
}

Now lets write a code for factorial of a number using recursive function.


#include
using namespace std;
int factorialRecursive(int n)
{
	if(n > 1)
        return n * factorialRecursive(n - 1);
    else
        return 1;
}
int main()
{
    int n;

    cout << "Enter a positive integer: ";
    cin >> n;

    cout << "Factorial of " << n << " = " << factorial(n);

    return 0;
}


Output:
Enter a positive integer: 5
Factorial of 5 = 120

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Caution! Recursion is very useful in certain situations but the use of recursion must be avoided unless you are very confident about what you are doing, recursion can wield undesired results if the code is not specific.