Program to find the next prime number

27 Jul, 2021
Given an integer N. The task is to find the next prime number i.e. the smallest prime number greater than N.
Examples: 
Input: N = 10 Output: 11 11 is the smallest prime number greater than 10.
Input: N = 0 Output: 2 
Approach:  
First of all, take a boolean variable found and initialize it to false.Now, until that variable not equals to true, increment N by 1 in each iteration and check whether it is prime or not.If it is prime then print it and change value of found variable to True. otherwise, iterate the loop until you will get the next prime number.
First of all, take a boolean variable found and initialize it to false.
Now, until that variable not equals to true, increment N by 1 in each iteration and check whether it is prime or not.
If it is prime then print it and change value of found variable to True. otherwise, iterate the loop until you will get the next prime number.
Below is the implementation of the above approach:  
C++
Java
Python3
C#
Javascript
// C++ implementation of the approach#include <bits/stdc++.h>using namespace std; // Function that returns true if n// is prime else returns falsebool isPrime(int n){    // Corner cases    if (n <= 1)  return false;    if (n <= 3)  return true;       // This is checked so that we can skip     // middle five numbers in below loop    if (n%2 == 0 || n%3 == 0) return false;       for (int i=5; i*i<=n; i=i+6)        if (n%i == 0 || n%(i+2) == 0)           return false;       return true;} // Function to return the smallest// prime number greater than Nint nextPrime(int N){     // Base case    if (N <= 1)        return 2;     int prime = N;    bool found = false;     // Loop continuously until isPrime returns    // true for a number greater than n    while (!found) {        prime++;         if (isPrime(prime))            found = true;    }     return prime;} // Driver codeint main(){    int N = 3;     cout << nextPrime(N);     return 0;}
// Java implementation of the approachclass GFG{     // Function that returns true if n    // is prime else returns false    static boolean isPrime(int n)    {        // Corner cases        if (n <= 1) return false;        if (n <= 3) return true;                 // This is checked so that we can skip        // middle five numbers in below loop        if (n % 2 == 0 || n % 3 == 0) return false;                 for (int i = 5; i * i <= n; i = i + 6)            if (n % i == 0 || n % (i + 2) == 0)            return false;                 return true;    }         // Function to return the smallest    // prime number greater than N    static int nextPrime(int N)    {             // Base case        if (N <= 1)            return 2;             int prime = N;        boolean found = false;             // Loop continuously until isPrime returns        // true for a number greater than n        while (!found)        {            prime++;                 if (isPrime(prime))                found = true;        }             return prime;    }         // Driver code    public static void main (String[] args)    {        int N = 3;             System.out.println(nextPrime(N));    }} // This code is contributed by AnkitRai01
# Python3 implementation of the approachimport math # Function that returns True if n# is prime else returns Falsedef isPrime(n):         # Corner cases    if(n <= 1):        return False    if(n <= 3):        return True         # This is checked so that we can skip    # middle five numbers in below loop    if(n % 2 == 0 or n % 3 == 0):        return False         for i in range(5,int(math.sqrt(n) + 1), 6):        if(n % i == 0 or n % (i + 2) == 0):            return False         return True # Function to return the smallest# prime number greater than Ndef nextPrime(N):     # Base case    if (N <= 1):        return 2     prime = N    found = False     # Loop continuously until isPrime returns    # True for a number greater than n    while(not found):        prime = prime + 1         if(isPrime(prime) == True):            found = True     return prime # Driver codeN = 3print(nextPrime(N)) # This code is contributed by Sanjit_Prasad
// C# implementation of the approachusing System;     class GFG{     // Function that returns true if n    // is prime else returns false    static bool isPrime(int n)    {        // Corner cases        if (n <= 1) return false;        if (n <= 3) return true;                 // This is checked so that we can skip        // middle five numbers in below loop        if (n % 2 == 0 || n % 3 == 0)            return false;                 for (int i = 5; i * i <= n; i = i + 6)            if (n % i == 0 ||                n % (i + 2) == 0)            return false;                 return true;    }         // Function to return the smallest    // prime number greater than N    static int nextPrime(int N)    {             // Base case        if (N <= 1)            return 2;             int prime = N;        bool found = false;             // Loop continuously until isPrime        // returns true for a number        // greater than n        while (!found)        {            prime++;                 if (isPrime(prime))                found = true;        }        return prime;    }         // Driver code    public static void Main (String[] args)    {        int N = 3;             Console.WriteLine(nextPrime(N));    }} // This code is contributed by 29AjayKumar
<script> // Javascript implementation of the approach // Function that returns true if n// is prime else returns falsefunction isPrime(n){    // Corner cases    if (n <= 1) return false;    if (n <= 3) return true;         // This is checked so that we can skip    // middle five numbers in below loop    if (n%2 == 0 || n%3 == 0) return false;         for (let i=5; i*i<=n; i=i+6)        if (n%i == 0 || n%(i+2) == 0)        return false;         return true;} // Function to return the smallest// prime number greater than N function nextPrime(N){     // Base case    if (N <= 1)        return 2;     let prime = N;    let found = false;     // Loop continuously until isPrime returns    // true for a number greater than n    while (!found) {        prime++;         if (isPrime(prime))            found = true;    }     return prime;} // Driver code     let N = 3;     document.write(nextPrime(N)); // This code is contributed by Mayank Tyagi </script>
5
 
gp6
Sanjit_Prasad
ankthon
29AjayKumar
mayanktyagi1709
sooda367
Prime Number
Mathematical
Mathematical
Prime Number
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