Points to Remember About Functions in C++
1. Most C++ program has a function called main() that is called by the operating system when a user runs the program.
2. Every function has a return type. If a function doesn’t return any value, then void is used as a return type. Moreover, if the return type of the function is void, we still can use the return statement in the body of the function definition by not specifying any constant, variable, etc. with it, by only mentioning the ‘return;’ statement which would symbolize the termination of the function as shown below:
C++
void function name( int a) { ....... // Function Body return ; // Function execution would get terminated } |
3. To declare a function that can only be called without any parameter, we should use “void fun(void)“. As a side note, in C++, an empty list means a function can only be called without any parameter. In C++, both void fun() and void fun(void) are same.
Functions in C++
A function is a set of statements that takes input, does some specific computation, and produces output. The idea is to put some commonly or repeatedly done tasks together to make a function so that instead of writing the same code again and again for different inputs, we can call this function.
In simple terms, a function is a block of code that runs only when it is called.
Syntax:
Example:
C++
// C++ Program to demonstrate working of a function #include <iostream> using namespace std; // Following function that takes two parameters 'x' and 'y' // as input and returns max of two input numbers int max( int x, int y) { if (x > y) return x; else return y; } // main function that doesn't receive any parameter and // returns integer int main() { int a = 10, b = 20; // Calling above function to find max of 'a' and 'b' int m = max(a, b); cout << "m is " << m; return 0; } |
m is 20
Time complexity: O(1)
Space complexity: O(1)