10 simple c++ programs for beginners

10 simple c++ programs for beginners

C++ is one the most popular languages in the programming world. In this article we will be looking towards 10 simple programs for beginners in CPP.

  1. Adding to numbers in C++.
    Ans. Take two variables and take user input and add them.

    #include <iostream>
    using namespace std;
    int main() {
    int a ;
    int b ;
    cin>>a>>b;
    cout<<a+b;
    return 0;
    }
    Input: 2 5
    Output: 7
  2. Check if a number is even or odd.
    Ans. If the given number is divisible by 2 then it is even otherwise odd.

    #include <iostream>
    using namespace std;
    int main() {
    int a ;
    cin>>a;
    if(a%2 == 0)  // if remainder is zero then even number
        cout<<”even”;
    else       cout<<”odd”;
    return 0;
    }
    Input: 8
    Output: even
  3. Write a program to swap two numbers.
    Ans. Use a temporary variable to store one of the numbers.

    #include <iostream>
    using namespace std;
    int main() {
    int a = 10;
    int b = 20;
    cout<<a<<" "<<b<<endl;
    int temp = a;
    a = b;
    b = temp;
    cout<<a<<" "<<b<<endl;
    return 0;
    }
    Output: 10 20
    20 10
  4. Write a program to find the largest number among three numbers.
    Ans. A number will be largest if number is greater than both the other numbers.

    #include <iostream>
    using namespace std;
    int main() {
    float a, b, c;
    cin >> a >> b >> c;
    if(a >= b && a >= c)
        cout << "Largest number: " << a;
    if(b >= a && b >= c)
        cout << "Largest number: " << b;
    if(c >= a && c >= b)
        cout << "Largest number: " << c;
    return 0;
    }
    Input: 1 2 3
    Largest number: 3
  5. Find the sum of all the natural numbers from 1 to n.
    Ans. We can do this using two ways, one is by iterating from 1 to n and adding them up while the other way is using the summation formula –
summation of i from 1 to n=n(n+1)/2=1+2+3+4+..+(n-1)+n

#include <iostream>
using namespace std;
int main()
{
    int n, sum = 0;
    cin >> n;
    for (int i = 1; i <= n; ++i) {
        sum += i;
    }
// or sum = n*(n+1)/2;
    cout << sum;
    return 0;
}
Input: 5
Output: 15
  1. Write a program to check whether a number is prime or not.
    Ans. A prime number is not divisible by any number smaller than it except 1. Basically, it has only two factors 1 and itself.

    #include <iostream>
    using namespace std;
    int main() {
    int a ;
    cin>>a;
    int b = 2;
    //start from b as 1 can divide any number
    bool prime = true;
    while(b!=a){
        if(a%b == 0)
            {
                prime = false;
                break;
            }
        b++;
    }
    if(prime)
    cout<<"prime";
    else cout<<"not prime";
    return 0;
    }
    Output: prime
  2. Compute the power a given number to a given power.
    Ans. We need to keep multiplying the same number power times.

    3^3=3*3*3=27
    #include <iostream>
    using namespace std;
    int main() 
    {
    int power;
    float base, result = 1;
    cin >> base >>power;
    while (power != 0) {
        result *= base;
        power--;
    }
    cout << result;
    return 0;
    }
    Input: 3 3
    Output: 27
  3. Calculate the average of all the elements present in an array.
    Ans.

    average= summation〖arr[i]〗/n
    #include <iostream>
    using namespace std;
    int main()
    {
    int n;
    cin>>n;
    int arr[n];
    float sum = 0.0;
    for(int i = 0;i<n;i++)
        cin>>arr[i];
    for(int i = 0;i<n;i++)
        sum += arr[i];
    cout<<(float)(sum/(float)n);
    return 0;
    }
    Input: 3
    1 4 5
    Output: 3.33333
  4. Write a program to find the GCD of two numbers.
    Ans. GCD is the greatest common divisor of the two numbers.

    #include <iostream>
    using namespace std;
    int gcd(int a,int b){
    if(b == 0)
        return a;
    return gcd(b,a%b);
    }
    int main() {
    int a ,b ;
    cin>>a>>b;
    cout<<gcd(a,b);
    return 0;
    }
    Input: 35 25
    Output: 5
  5. Write a function to find the length of a string in CPP.
    Ans. Iterate through the string and increase count by 1 till we reach the end of the string.

    #include <iostream>
    using namespace std;
    int main() 
    {
    string str;
    cin>>str;
    int count = 0;
    for(int i = 0;str[i];i++) // till the string character is null
        count++;
    cout<<count;
    }
    Input: abcde
    Output: 5
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