Using define in C++

#include <iostream>
using namespace std;
#define PI 3.1416

int main()
{
    double r;
    cin>>r;
    cout<<"The area of the circle is "<<PI*r*r<<endl;
    return 0;
}

Sorting an array in C++

#include <iostream>
#include <algorithm>
using namespace std;
int a[5]={2,1,4,5,6};

int main()
{
    sort(a,a+5);
    for(int i=0;i<5;i++){
        cout<<a[i]<<endl;
    }
    return 0;
}

Simple character array in c++

#include <iostream>
#include <cstring>
using namespace std;
int main()
{
    char as[]={'R','S','T','R','J'};
    int len = strlen(as)-1;
    for(int i=0;i<len;i++){
        cout<<as[i]<<endl;
    }
    return 0;
}

Array in C++

#include <iostream>
using namespace std;
int main()
{
    int a[3]={3,1,2};
    for(int i=0;i<3;i++){
        cout<<a[i]<<endl;
    }
    return 0;
}

Function without any return type

#include <iostream>
using namespace std;

void add(int x, int y){
    int res = x+y;
    cout<<res<<endl;
}

int main()
{
    int x,y;
    x=2;
    y=5;
    add(x,y);
    return 0;
}

Simple Addition function in C++

#include <iostream>
using namespace std;

int add(int x, int y){
    int res = x+y;
    return res;
}

int main()
{
    int x,y;
    x=2;
    y=5;
    cout<<add(x,y)<<endl;
    return 0;
}

While Loop in C++

#include <iostream>
using namespace std;
int main()
{
    int i=0;
    while(i<5){
        cout<<"I love C++"<<endl;
        i++;
    }
    return 0;
}