C++ Program to find out the Prime number's By sieve Method

NOTE : YOU CAN DOWNLOAD EXE FILE HERE: SIEVE.EXE

SORUCE CODE (RTF): source.cpp click here

 1  #include <iostream>

 2  #include <conio.h>

 3  using namespace std;

 4  int main()

 5 

 6  {

 7 

 8  int number,n=2;

 9  cout<<"Program to find out Prime number by sieve method\n\n\a";

10 

11  cout<<"Enter upto which number you want to find out the prime number\n";

12  cin>>number;

13  int arr[number];

14  for(int i=0;i<number;i++)

15  arr[i]=i+1;

16  cout<<"  Original number:\n";

17 

18  for(int i=0;i<number;i++)

19  {

20 

21 

22      cout<<arr[i]<<"\t\a";

23 

24  }

25  while((n*n)<number) // while n² is less than original  number

26 

27  {

28 

29  for(int i=n;i<number;i++)

30  {

31  if(arr[i]%n==0)

32  {

33  arr[i]=-1;

34  }

35  }

36  n++;

37 

38 

39  }

40  cout<<" \n\n Sieve Format:\n";

41 

42  for(int i=0;i<number;i++)

43  {

44 

45      if(arr[i]==-1) cout<<"X\t";

46  else

47 

48      cout<<arr[i]<<"\t\a";

49 

50  }

51  cout<<"  Prime number's are given belows:\n";

52 

53  for(int i=0;i<number;i++)

54  {

55 

56      if(arr[i]==-1) continue;

57 

58 

59      cout<<arr[i]<<"\t\a";

60 

61  }

62 

63  getch();

64  }

NOTE : YOU CAN DOWNLOAD EXE FILE HERE: SIEVE.EXE