how to make a function in c 2b 2b

1// function example
2#include <iostream>
3using namespace std;
4
5int addition (int a, int b)
6{
7  int r;
8  r=a+b;
9  return r;
10}

1#include <iostream>
2
3using namespace std;
4
5void function(){
6    cout << "I am a function!" << endl;
7}
8
9int main()
10{
11    function();
12
13    return 0;
14}

1void Hello() {
2  std::cout << "Hello";
3}
4
5int main () {
6  Hello();
7}

1#include <iostream>
2#include <stdlib.h>
3#include <iomanip>
4#include <fstream>
5using namespace std;
6
7void function_one(double, double, double);
8
9int main() {
10  double r1 = 1.0;
11  double r2 = 2.0;
12  double x = 0.0;
13  function_one(r1, r2, x);
14  return 0;
15}
16
17void function_one(double rmin, double rmax, double x0) {
18  cout << "Function got called" << endl;
19}

1//first lets create a function
2/*void is for starting something, anything after void will be the name of your
3function which will be followed by () */
4void yourFunction() {
5//your code will be here, anything here will be the code in the yourFunction
6  cout << "Functions"
7}
8//now we have to go to our main function, the only function the compiler reads
9int main() {
10  myFunction(); //you call the function, the code we put in it earlier will be executed
11  return 0;
12}

1// function returning the max between two numbers
2 
3int max(int num1, int num2) {
4   // local variable declaration
5   int result;
6 
7   if (num1 > num2)
8      result = num1;
9   else
10      result = num2;
11 
12   return result; 
13}
14