11 Implement the C program in which main program accepts an integer array. Main program uses the FORK system call to create a new process called a child process. Parent process sorts an integer array and passes the sorted array to child process through the command line arguments of EXECVE system call. The child process uses EXECVE system call to load new program which display array in reverse order. ~ Coding Atharva

Program Parent.c:

#include<stdio.h> 
#include<stdlib.h>
#include <string.h>

void bubbleSort(int arr[],int n)
{
    printf("\n Sorting Started \n");
    
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<n-1;j++)
        {
            if(arr[j] > arr[j+1])
            {
                int temp = arr[j];
                arr[j] = arr[j+1];
                arr[j+1] = temp;
            }
        }
    }
    
    printf("\n\n Sorting Completed! \n");   
}

// To Convert Integer to Char*
void tostring(char str[], int num)
{
    int i, rem, len = 0, n;
 
    n = num;
    while (n != 0)
    {
        len++;
        n /= 10;
    }
    for (i = 0; i < len; i++)
    {
        rem = num % 10;
        num = num / 10;
        str[len - (i + 1)] = rem + '0';
    }
    str[len] = '\0';
}

void main(int argc, char *argv[])
{
    printf("\n This is the main process: ");
    printf("\n Process Id: %d",getpid());
	printf("\n Parent Id: %d",getppid());
    

    int arr[] = {10,5,1,60,20};
    int n = 5;
    printf("\n\n Sorting Array using Bubble Sort:");
    bubbleSort(arr,n);


    printf("\n Forking the current process:");
    pid_t cpid = fork();
    //The pid_t data type is a signed integer type which is capable of representing a process ID. 


    if(cpid > 0)
    {
        printf("\n\n Parent is Running:\n ParentID: %d \n It's ID: %d \n",getppid(),getpid());

        printf("\n Parent is waiting for child to Complete! \n\n");
        
        wait(NULL);
 
        printf("\n\n Parent is Exiting!!\n"); 
    }
    else if(cpid == 0)
    {
        printf("\n\n Child is running:\n ParentID: %d \n It's ID: %d \n",getppid(),getpid());

        char *arrChar[n+1];

        // Creating Ascii Character Array to Pass
        // as command line Argument
        arrChar[0] = (char *) "child";   // Arg 0 = name of executable file
        for(int i=0;i<n;i++)
    	{
            char *string = malloc (sizeof(char) * (20));
            tostring(string,arr[i]);
            arrChar[i+1] = string;
        }
        arrChar[n+1] = NULL;

        printf("\n\n Child Calling EXECV System Call:\n");
        execv("./child",arrChar);

        printf("\n\n Child EXECV Call Complete\n");
        printf("\n\n Child Execution Complete \n");
    }   
    else if(cpid < 0)
    {
        printf("Error");
    }
}

Program Child.c:

#include <stdio.h>
#include<stdlib.h>

void main(int argc, char *argv[])
{ 
    /* argv[0] is the program name */
    
    int *data = (int *) malloc((argc) * sizeof(int));
    
    printf("\n Argc:%d",argc);
    for(int i = 0;i < argc;i++) 
    {
        data[i] = atoi(argv[i]);
    }

    // Printing Element in Reverse
    printf("\n Printing Element in Reverse:");
    for(int i = argc-1; i>0;i--)
    {
        printf(" %d ",data[i]);
    }
    
    printf("\n\n EXCEV task Completed \n");
}

Output:

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