how to remake random numbers in C++

Question

I am trying to make a game of Rock Paper Scissors that after complied will be replayable but the random numbers I use for the starting game to pick the A.I.'s choice are reused for every following game. Can someone please explain why and how to fix it.

my code:
#include <iostream>
#include <cstdlib> //used for rand()
#include <ctime> //used for srand(time())
using namespace std;

/* How to play
1.) hit run
2.) type rock, paper, or scissors
3.) hit sumbit
4.) read the output for the result
WARNING!!! do NOT capitalize rock, paper, or scissors */

int main() {

srand(time(0)); //uses systems time to make random number

string player;
char playing ='y';
int comp = 1 + (rand() % 3); //picks a randome number between 0 and 2 based off srand and adds 1

while (playing == 'y') {

cout << "Rock...Paper...Scissors...1...2...3...Shoot" << endl;

cin >> player; //players choice

if (player == "rock") {

if (comp == 1) {

cout << "Rock! It's a tie" <<endl;
}
else if (comp == 2) {

cout << "paper! I win!" <<endl;

}
else {

cout << "Scissors! You win!" <<endl;
}

}

else if (player == "paper") {

if (comp == 1) {

cout << "Rock! You win!" <<endl;
}
else if (comp == 2) {

cout << "paper! It's a tie!" <<endl;

}
else {

cout << "Scissors! I win!" <<endl;
}

}

else if (player == "scissors") {

if (comp == 1) {

cout << "Rock! I win" <<endl;
}
else if (comp == 2) {

cout << "paper! You win!" <<endl;

}
else {

cout << "Scissors! It's a tie!" <<endl;
}

}

else {
cout << "invalid choice";

Answer 1

Add the comp variable in the while loop
your srand is okay
but you don't change the value of comp

Answer 2

I tried moving srand into the if statement and that didn't help