C++ Program to Implement Sieve of Eratosthenes

This C++ program to implement Sieve of Eratosthenes. The program initializes an integer array with all the elements initialized to 0. Then the algorithm follows where the each non-prime element’s index is marked as 1 inside the nested loops. The prime numbers are those whose value of index is marked as 0.

Here is the source code of the C++ program illustrates how to pass a variable to a function by value. The C++ program is successfully compiled and run on a Linux system. The program output is also shown below.

```
/*
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 * C++ Program to implement Sieve of Eratosthenes

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 */
```
```
 
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#include <iostream>
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const int len = 100;
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```
 
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int main()
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{
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    int arr[100] = {0};
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```
 
```
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    for (int i = 2; i < 100; i++)
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    {
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        for (int j = i * i; j < 100; j+=i)

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        {
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            arr[j - 1] = 1;
```
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        }
```
```
    }
```
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    for (int i = 1; i < 100; i++)
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    {
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        if (arr[i - 1] == 0)
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            std::cout << i << "\t";
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    }
```
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}
```

$ a.out
1       2       3       5       7       11      13      17      19      23
29      31      37      41      43      47      53      59      61      67
71      73      79      83      89      97