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4 years ago

A firewall, when properly implemented, can prevent most attacks on your system.

2 answers:

5 0

This is true, A firewall is used to get rid of viruses and attackers and keep them out of your computer. But if not properly implemented can do next to nothing for you.

SpyIntel [72]4 years ago

4 0

The answer is A.True
Please give brainliest answer.

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OBJECTIVE This project will familiarize you with the use of pthreads, pthread mutexes and pthread condition variables. Your prog

zysi [14]

Answer:

Check the explanation

Explanation:

This program will simulate a tunnel with a limit of how many cars may move through it,

and will also simulate the cars going north and south-bound through the tunnel. We will

use pthreads, pthread mutexes, and pthread condition variables to simulate this.

#include <iostream>

#include <fstream>

#include <sstream>

#include <string>

#include <unistd.h>

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <pthread.h>

#include <string.h>

#include <signal.h>

#include <sys/types.h>

using namespace std;

#define MAXTHREADS 128

static int maxCarsInTunnel;

static int maxNCarsInTunnel;

static int maxSCarsInTunnel;

static int totalNCars;

static int totalSCars;

static int currentCarsInTunnel;

static int currentNCarsInTunnel;

static int currentSCarsInTunnel;

static int numCarsWaiting;

static pthread_mutex_t lockAccess = PTHREAD_MUTEX_INITIALIZER;

static pthread_cond_t cond = PTHREAD_COND_INITIALIZER;

void *northCar(void *arg);

void *southCar(void *arg);

struct car {

int carNo;

int travelTime;

bool waited;

};

int main() {

pthread_t cartid[MAXTHREADS];

int storage = 0;

cin >> maxCarsInTunnel;

cin >> maxNCarsInTunnel;

cin >> maxSCarsInTunnel;

cout << "Maximum number of cars in the tunnel: " << maxCarsInTunnel << endl;

cout << "Maximum number of northbound cars: " << maxNCarsInTunnel << endl;

cout << "Maximum number of southbound cars: " << maxSCarsInTunnel << endl;

unsigned int arrival_time;

char direction;

unsigned int traversal_time;

struct car argList;

while (cin >> arrival_time >> direction >> traversal_time) {

sleep(arrival_time);

argList.travelTime = traversal_time;

argList.waited = false;

if (direction == 'N') {

totalNCars++;

argList.carNo = totalNCars;

pthread_create(&cartid[storage], NULL, northCar, (void *) &argList);

}

else if (direction == 'S') {

totalSCars++;

argList.carNo = totalSCars;

pthread_create(&cartid[storage], NULL, southCar, (void *) &argList);

}

storage++;

}

for (int i = 0; i < storage; i++) {

pthread_join(cartid[i], NULL);

}

cout << totalNCars << " northbound car(s) crossed the tunnel." << endl;

cout << totalSCars << " southbound car(s) crossed the tunnel." << endl;

cout << numCarsWaiting << " car(s) had to wait." << endl;

return 0;

}

void *northCar(void* arg) {

int tunnelTime;

int carNum;

bool wait;

struct car *argptr;

argptr = (struct car *) arg;

tunnelTime = argptr->travelTime;

carNum = argptr->carNo;

wait = argptr->waited;

pthread_mutex_lock(&lockAccess);

cout << "Northbound car # " << carNum << " arrives at the tunnel." << endl;

while (currentNCarsInTunnel >= maxNCarsInTunnel || currentCarsInTunnel >= maxCarsInTunnel) {

if (wait == false) {

wait = true;

numCarsWaiting++;

}

pthread_cond_wait(&cond, &lockAccess);

}

currentNCarsInTunnel++;

currentCarsInTunnel++;

cout << "Northbound car # " << carNum << " enters the tunnel." << endl;

pthread_cond_signal(&cond);

pthread_mutex_unlock(&lockAccess);

sleep(tunnelTime);

pthread_mutex_lock(&lockAccess);

cout << "Northbound car # " << carNum << " exits the tunnel." << endl;

currentNCarsInTunnel--;

currentCarsInTunnel--;

pthread_cond_broadcast(&cond);

pthread_mutex_unlock(&lockAccess);

}

void *southCar(void* arg) {

int tunnelTime;

int carNum;

bool wait;

struct car *argptr;

argptr = (struct car *) arg;

tunnelTime = argptr->travelTime;

carNum = argptr->carNo;

wait = argptr->waited;

pthread_mutex_lock(&lockAccess);

cout << "Southbound car # " << carNum << " arrives at the tunnel." << endl;

while (currentSCarsInTunnel >= maxSCarsInTunnel || currentCarsInTunnel >= maxCarsInTunnel) {

if (wait == false) {

wait = true;

numCarsWaiting++;

}

pthread_cond_wait(&cond, &lockAccess);

}

currentSCarsInTunnel++;

currentCarsInTunnel++;

cout << "Southbound car # " << carNum << " enters the tunnel." << endl;

pthread_cond_signal(&cond);

pthread_mutex_unlock(&lockAccess);

sleep(tunnelTime);

pthread_mutex_lock(&lockAccess);

cout << "Southbound car # " << carNum << " exits the tunnel." << endl;

currentSCarsInTunnel--;

currentCarsInTunnel--;

pthread_cond_broadcast(&cond);

pthread_mutex_unlock(&lockAccess);

}

Kindly check the attached images below to see the code screenshot and code output.

8 0

4 years ago

Create a trigger that prevents anychange(insert, update, or delete)to the grade attribute of the takesrelation that would change

Alchen [17]

Answer:

The trigger code is given below

create trigger F1_Del

after delete on Friend

for each row

when exists (select * from Friend

where ID1 = Old.ID2 and ID2 = Old.ID1)

begin

delete from Friend

where (ID1 = Old.ID2 and ID2 = Old.ID1);

end

create trigger F1_Insert

after insert on Friend

for each row

when not exists (select * from Friend

where ID1 = New.ID2 and ID2 = New.ID1)

begin

insert into Friend values (New.ID2, New.ID1);

end

5 0

3 years ago

2.3 Code Practice: Question 3

Tpy6a [65]

Answer:

Code in C++

Explanation:

C++ Code

#include<iostream> //for input and output

using namespace std;

int main()

{

int hour;

int minute;

cout<<"Enter the hour:";

cin>> hour;

cout<<"Enter the minute:";

cin>>minute;

minute = minute+15;

if(minute>=60){

hour++;

minute=minute-60;

}

if(hour>=24){

hour=0;

}

cout<<"Hours: "<<hour<<endl;

cout<<"Minutes:"<<minute;

return 0;

}

Code Explanation

First we need to declare two int variables to hold hour and minute values input from user.

Check if by adding 15 minutes into minute entered by user is greater then or equal to 60 then increment into hour and subtract 60 from minute.

Another check is that if user enters more then 24 hour or by making increment into hour, the hour values i greater then or equal to 24 then we need to change the hour to 0.

Result

Case 1:

Enter the hour:8

Enter the minute:15

Hours: 8

Minutes:30

Case 2:

Enter the hour:9

Enter the minute:46

Hours: 10

Minutes:1

8 0

3 years ago

Describe a psychological challenge of space travel that astronauts can face.

Anna11 [10]

Answer:

Loneliness

Explanation:

It is logical that an astronaught could be lonely up in space due to the absence of loved ones.

6 0

3 years ago

When both inputs of a J-K edge-triggered FF are high and the clock cycles, the output will ________.

shutvik [7]

Answer:

Explanation:

Toggle

5 0

3 years ago