Operating_System

#include <stdio.h>  // for printf, scanf and perror
#include <stdlib.h>  // for atoi
#include <unistd.h> // for pipe
#include <sys/types.h> // for pid_t
#include <string.h> // for strcmp

// function to calculate sum of array
int summation(int n, int* arr){
    int sum = 0;
    for(int i = 0; i < n; i++)
        sum += arr[i];
    return sum;
}

// function to sort array using bubble sort
void Bubble_Sort(int n, int* arr){
    for(int i = 0; i < n; i++){
        for(int j = 0; j < n - i - 1; j++){
            if(arr[j] > arr[j + 1]){
                int temp = arr[j];
                arr[j] = arr[j + 1];
                arr[j + 1] = temp;
            }
        }
    }
}


// function to check for error in pipe
void checkerror(int err, char* msg){
    /*
        Print a message describing the meaning of the value of errno.
        This function is a possible cancellation point and therefore not marked with __THROW.
    */
    if(err == -1){
        perror(msg);
        exit(-1);
    }
}

// function to get max element from array
int get_max(int n, int* arr){
    int max = arr[0];
    for(int i = 1; i < n; i++){
        if(arr[i] > max)
            max = arr[i];
    }
    return max;
}


// function to get min element from array
int get_min(int n, int* arr){
    int min = arr[0];
    for(int i = 1; i < n; i++){
        if(arr[i] < min)
            min = arr[i];
    }
    return min;
}

// function to get average of array
float get_avg(int n, int* arr){
    int sum = 0;
    for(int i = 0; i < n; i++)
        sum += arr[i];
    return (float)sum / n;
}

// function to get median of array
float get_median(int n, int* arr){
    if(n % 2 == 0){
        int mid = n / 2;
        return (float)(arr[mid] + arr[mid - 1]) / 2;
    }
    else{
        int mid = n / 2;
        return arr[mid];
    }
}

// function to get number of prime numbers in array
int get_prime(int n, int* arr){
    int count = 0;
    for(int i = 0; i < n; i++){
        int flag = (arr[i] == 1) ? 1 : 0;
        for(int j = 2; j < arr[i]; j++){
            if(arr[i] % j == 0){
                flag = 1;
                break;
            }
        }
        if(flag == 0)
            count++;
    }
    return count;
}

int main(int argc, char* argv[]){

    // declare pipe
    int pipefds[2];

    // The pid_t data type is a signed integer type which is capable of representing a process ID. In the GNU library, this is an int.
    pid_t childpid;

    // create pipe
    childpid = pipe(pipefds);

    // check for error
    checkerror(childpid, "Unable to create pipe");

    // getting n from command line
    int n = atoi(argv[1]);

    // declare input and output array of size n
    int input[n], output[n];

    // get input array
    printf("Enter %d numbers seperated by spaces: ", n);
    for(int i = 0; i < n; i++)
        scanf("%d", &input[i]);

    // 0 for read  (child process will read from pipe)
    // 1 for write (parent process will write to pipe)

    // parent process will write to pipe
    write(pipefds[1], input, sizeof(input));

    // child process will read from pipe
    read(pipefds[0], output, sizeof(output));

    // print output array
    printf("\nArray: ");
    for(int i = 0; i < n; i++)
        printf("%d ", output[i]);

    for(int i = 1; i < argc; i++){
        if(!strcmp(argv[i], "max")){
            printf("\nMax Element: %d", get_max(n, output));
        }else if(!strcmp(argv[i], "min")){
            printf("\nMin Element: %d", get_min(n, output));
        }else if(!strcmp(argv[i], "avg")){
            printf("\nAverage: %0.2f", get_avg(n, output));
        }else if(!strcmp(argv[i], "median")){
            printf("\nMedian: %0.1f", get_median(n, output));
        }else if(!strcmp(argv[i], "primes")){
            printf("\nNumber of Prime Numbers: %d", get_prime(n, output));
        }else if(!strcmp(argv[i], "sum")){
            printf("\nSum: %d", summation(n, output));
        }else if(!strcmp(argv[i], "sort")){
            Bubble_Sort(n, output);
            printf("\nSorted Array: ");
            for(int i = 0; i < n; i++)
                printf("%d ", output[i]);
            printf("\n");
        }
    }
}