I have written this code in C++ to print nth prime number. How can I write this code through recursion?

Question

1.00/5 (1 vote)

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C++

#include<iostream>
using namespace std;
int main()
{
    int a,j=2,c=0;
    cin>>a;
    for(int i=2;i<(a*a);i++)
    {   for( j=2;j<i;j++)>
        {
            if(i%j==0)
                break;

        }
        if(i==j)
        {
            c++;
            if(c==a)
            {
                cout<<i;  return 0;
            }
        }
    }
    return 0;
}

What I have tried:

i have written this code to print the nth prime number and want to develop it through recursive function.

Posted 7-May-16 1:50am

Member 12508519

Updated 7-May-16 3:40am

Patrice T

v2

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Sergey Alexandrovich Kryukov 7-May-16 11:10am

Why, why recursion? How many numbers do you want to find? This is, obviously enough, a problem for the iteration algorithm.
—SA

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Patrice T · Answer 1 · 2016-05-07T03:36:00

Bug report: On first look I would say that your program fail to find the first prime.

Question: why do you want to use recursion to find if a number is prime ?
Ok it may simplify the code, but it is at expense of PC resources, for large numbers you are at rick of stack overflow.
If you write the recursive code very carefully, it is possible to take advantage of the terminal recursion optimization depending on compiler capabilities.

Also your program is far from optimized, you use a very naive method. If you want to optimize the code, huge gains can be achieved.

OriginalGriff · Answer 2 · 2016-05-07T02:18:00

Solution 1

Google is your friend: recursive prime - Google Search[^]

Posted 7-May-16 2:18am

OriginalGriff