Inline Functions and Default arguments
- 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.