generating random numbers and checking for number of prime numbers

Question

I want to create a program that generates random numbers and then asks a user to enter number of prime numbers that have been generated. If the number is correct, the user is declared winner, else, loses. Please help.

OK, thank you to share your wishes. What's your question? A question to be on-topic on SO must describe a specific problem, what you tried to solve it and where you stopped. _"These are my requirements, what to do?"_ questions are off-topic. I'd also suggest to read FAQ before asking. — Adriano Repetti, Jul 31 '14 at 09:12
Propose a code with a problem and we can help you fixing it. But nobody's going to do the work for you from scratch... — jpo38, Jul 31 '14 at 09:25
@user3501133: Check out for random number :http://stackoverflow.com/questions/822323/how-to-generate-a-random-number-in-c . Since the prime numbers are probably reasonably small I would just brute force if they are prime. — Lucas, Jul 31 '14 at 09:26

score 3 · Answer 1 · answered Jul 31 '14 at 09:35

Use standard C functions srand and rand declared in header <stdlib.h> to generate random numbers. Then write a function that determinates whether a given number is a prime number. Take into account that 1 is not a prime number. You can find yourself many examples of such functions here at stackoverflow.

Good luck!:)

Sathish · Accepted Answer · 2017-11-02T06:31:29.787

Try this code-

#include<stdio.h>
#include<stdlib.h>
#include<sys/types.h>
#include<unistd.h>
int main()
{
    int arr[10], i, j, n, count=0;
    srand(getpid()); //Every time it will give the different seed to rand(), so you wont get same array again and again
    for (i = 0; i < 10; i++)
        arr[i] = (rand()%100) + 1;

    printf("Enter the No of prime numbers!\n");
    scanf("%d", &n);

    for (i = 0; i < 10; i++) {
        for (j = 2; j < arr[i]; j++)
            if (arr[i]%j == 0)
                break;
        if (arr[i] == j)
            count++;
    }
    printf("Prime Num in Array = %d, User I/p = %d\n",count,n);
    if(count == n)
        printf("Yeah! You have guessed correctly!\n");
    else
        printf("Sorry! Try again!\n");
    return 0;
}

Sample output-

root@ubuntu:~/c/basics# ./a.out 
Enter the No of prime numbers!
3
Prime Num in Array = 1, User I/p = 3
Sorry! Try again!
root@ubuntu:~/c/basics# ./a.out 
Enter the No of prime numbers!
2
Prime Num in Array = 2, User I/p = 2
Yeah! You have guessed correctly!

You code is bad. For example function main shall have return type int or getpid is not a standard C function. So its declaration can be absent in the used headers. — Vlad from Moscow, Jul 31 '14 at 09:48

generating random numbers and checking for number of prime numbers

2 Answers2