The document discusses different types of functions in C++ including: 1) Main functions are mandatory while other programs define additional functions. Functions are declared with a return type, name, and parameters. 2) Functions are defined with a syntax including the return type, name, parameters, and body. Functions can be called within other functions or the main function by passing values. 3) Inline functions have their code placed at the call site at compile time to avoid function call overhead. They are defined using the inline keyword before the return type for small, single line functions. 4) Functions can have default arguments which are values provided in the declaration that are used if not passed to the function. They must

1. Functions
• A function is a group of statements that together
perform a task.
• main() -> mandatory function =
• Various programs define additional functions.
• A function declaration tells the compiler about a
function's name, return type, and parameters. A
function definition provides the actual body of the
function.

2. Function Declaration
• A function can be defined as:
Syntax : return_type function_name(arguments)
{
body of the function
}
For e.g :
int add(int a,int b)
{
return a+b;
}

3. Calling a Function
• A function can be called
in a main() function or in
other functions.
• When it is called inside
itself than it called as
recursive function.
main()/function_1()
{
body
function(passing values);
}
For e.g :
main()
{
int a,b;
cout<<“Sum=“<<add(a,b);
}
int add(int x,int y)
{
return x+y;
}

4. Inline Functions
• If a function is inline than:
– Compiler puts its code at the place
where it is called at compile time
– To define a function as inline
function
• use the keyword “inline” just
before the return type.
– The compiler ignore the inline
qualifier in case defined function is
more than a line.
inline return_type
function_name(args)
{
//one line code
}

5. Inline Function (example)
#include <iostream>
using namespace std;
inline int Max(int x, int y)
{
return (x > y)? x : y;
}
// Main function for the program
int main( )
{
cout << "Max (20,10): " << Max(20,10) << endl;
cout << "Max (0,200): " << Max(0,200) << endl;
cout << "Max (100,1010): " << Max(100,1010) <<
endl;
return 0;
}
Output:
Max (20,10): 20
Max (0,200): 200
Max (100,1010): 1010

6. Why Inline functions
• Objective of using functions:
– To save memory space, when a
function is likely to be called
many times.
Jumping to a function
Saving the registers
Pushing arguments in to the
stack
Returning to the calling
function
• When a function is small enough
(only one line of code) these
things would be a wastage of
time and resources.

7. Function with Default Arguments
• A default argument is a value
provided in function
declaration that is
automatically assigned by the
compiler if caller of the
function doesn’t provide a
value for the argument with
default value.
return _type f_name (arg1,arg2,arg3=value)
• When a default argument is placed then all the other arguments
after that must be default arguments only.
• That says the default arguments must placed on right most side of
all the arguments collectively

8. Default arguments (example)
int sum(int x, int y, int z=0, int w=0)
{
return (x + y + z + w);
}
int main()
{
cout << sum(10, 15) << endl;
cout << sum(10, 15, 25) << endl;
cout << sum(10, 15, 25, 30) <<
endl;
return 0;
}
Output:
25
50
80

9. Default Arguments
• They may come in handy when some arguments
are having the same values.
– For e.g. Bank interest may remain the same for all
the customers for a particular period of deposit.