# C++ Program to Generate Random Numbers using Middle Square Method

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This is a C++ Program to generate random numbers using Middle Square method. In mathematics, the middle-square method is a method of generating pseudorandom numbers. In practice it is not a good method, since its period is usually very short and it has some severe weaknesses, such as the output sequence almost always converging to zero.

Here is source code of the C++ Program to Generate Random Numbers Using Middle Square Method. The C++ program is successfully compiled and run on a Linux system. The program output is also shown below.

1. `#include <iostream>`
2. `#include <math.h>`
3. `#include <stdlib.h>`
4. ` `
5. `using namespace std;`
6. ` `
7. `int a[] = { 1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000 };`
8. `int middleSquareNumber(int numb, int dig)`
9. `{`
10. `    int sqn = numb * numb, next_num = 0;`
11. `    int trim = (dig / 2);`
12. `    sqn = sqn / a[trim];`
13. `    for (int i = 0; i < dig; i++)`
14. `    {`
15. `        next_num += (sqn % (a[trim])) * (a[i]);`
16. `        sqn = sqn / 10;`
17. `    }`
18. `    return next_num;`
19. `}`
20. ` `
21. `int main(int argc, char **argv)`
22. `{`
23. `    cout << "Enter the #-digit random numbers you want: ";`
24. `    int n;`
25. `    cin >> n;`
26. `    int start = 1, end = 1;`
27. ` `
28. `    start = a[n - 1];`
29. `    end = a[n];`
30. ` `
31. `    int number = ((rand()) % (end - start)) + start;`
32. `    cout << "The random numbers are:\n" << number << ", ";`
33. `    for (int i = 1; i < n; i++)`
34. `    {`
35. `        number = middleSquareNumber(number, n);`
36. `        cout << number << ", ";`
37. `    }`
38. `    cout << "...";`
39. `}`

Output:

```\$ g++ MiddleSquare.cpp
\$ a.out

Enter the #-digit random numbers you want: 5
The random numbers are:
10041, 16426, 796264, -276041, -115546, ...```

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