Question

C programm , ´hello i need your help

-Given the C program primes.c with the following main method:

int main()
{
    int num, res;
    char buffer[11];
    bool finished = false;
    while (!finished)
    {
        printf("Enter n > 0 or quit\n");
        scanf("%10s", buffer);
        if (strcmp(buffer, "quit") == 0) {
            finished = true;
        } else {
            // Convert input to number and compute n-th prime
            num = atoi(buffer);
            if (num > 0) {
                res = nth_prime(num);
                printf("Prime #%d is %d\n", num, res);
            } else {
                printf("Invalid input!\n");
            }
        }
    }
    return 0;
}

The function nth_prime calculates the (very complex) then n-th prime for a parameter n>0(see full program code in primes.c ).

Adjust the program so that the calculation and output of the n-ten primes after user input from n is adopted by a child process so that the user can start further calculations by inputs in the parent process while calculations are in progress.

If the user enters the command wait, the parent process should wait for all calculations to complete. If the program also quit ends, it is also necessary to wait for the termination of all child processes.

Note: Test your implementation with input values n in the five-digit range, so that the calculations take several seconds.

Answer 1

Program :

int nth_prime(int num) {
int c;
for ( c = 2 ; c <= num - 1 ; c++ ) {
if ( num%c == 0 )
return 0;
}
if (c == num)
return 1;
}

int main()
{
int num, res;
char buffer[11];
bool finished=false;
while (!finished)
{
printf("Enter n > 0 or quit\n");
scanf("%10s", buffer);

if (strcmp(buffer, "quit") == 0) {
finished = true;
} else {   
num = atoi(buffer);
if (num > 0) {
res = nth_prime(num);
printf("Prime #%d is %d\n", num, res);
} else {
printf("Invalid input!\n");
}
}
}
return 0;
}

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Output :

Case 1 :

Enter n > 0 or quit

123456

Prime #123456 is 0

Case 2 :

Enter n > 0 or quit

quit

***********************************************************************************************