Prime numbers for a given range

#1

Take as input a Number N and Print all the prime numbers from 2 to N

#include
using namespace std;
void prime(int *a)
{
for(int i=3;i<=1000000;i+=2)
a[i]=1;

for(long long i=3;i<=1000000;i+=2)
{
if(a[i]==1)
{
for(long long j=i*i;j<=1000000;j+=i)
a[j]=0;
}
}
a[0]=a[1]=0;
a[2]=1;
}
int main()
{

int a[1000005]={0};
prime(a);

int n;
cin>>n;
for(int i=2;i<=n;i++)
{
if(a[i]==1)
cout<<i<<", ";

}
cout<<"\b\b\b"<<endl ;

return 0;

}

why am i not getting correct output with all the test cases.

#2

Make the array global.

#3

done still not working

#4

Please share the changed code by running it on the coding blocks ide, ide.codingblocks.com

#5
#6

there is an error due to } but thats not the real issue find the real one.

#7

I told you make the array global, it’s still not global

#8

still but how to remove the last ,(comma)?

#9

I don’t understand, wait I’ll correct the code myself.

#10

Here is your corrected code https://ide.codingblocks.com/s/319248

#11

thanks
for the help keshav

#12


whats wrong in this code to reverse the array

#13

Change your loop to

for(int i=0;i<a/2+(a%2);i++)

{

    swap(ar[i],ar[a-i-1]);

}
#14

still not getting the correct answer

#15

only

Screenshot 2020-08-25 at 10.19.12 AM
Screenshot 2020-08-25 at 10.19.12 AM1440×900 204 KB

#16

can you provide me with the link of the question

#17

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