Generating numbers outside of my range C++ (way too large) - c++

Question

I decided for fun to try and make a simple program that "sort of" simulates blackjack in a dumbed down way. It's basically done, except for the fact that the randomly generated numbers are WAY too large. I don't care about the bias srand/rand has (for now) I just want to get it working properly.
#include <iostream>
#include <cstdlib>
#include <cmath>
#include <ctime>
using namespace std;
int genRandInt (int low, int high) {
int randnum = low + (rand() % (high - low + 1));
return randnum;
}
int main()
{
srand(time(NULL));
int computerScore;
int score;
int card;
while (int playAgain = 1)
{
cout << "Enter 0 to hold or 1 to hit: ";
int play;
cin >> play;
if (play == 0)
{
computerScore = genRandInt(1, 31);
if (score < computerScore)
{
cout << "Your score is " << score << " and the computer's score is " << computerScore << "! You lose.\n";
}
if (score > 21)
{
cout << "Your score is " << score << " which is greater than 21. Bust!\n";
}
if (score > computerScore && score <= 21)
{
cout << "Your score is " << score << " and the computer's score is " << computerScore << "! You win!\n";
}
cout << "Would you like to play again? 1 for yes, 0 for no. : ";
cin >> playAgain;
}
if (play == 1)
{
card = genRandInt(1, 11);
score = score + card;
cout << "Your score is: " << score << "\n";
}
}
return 0;
}
Any ideas?

Answer 1

You use int score; uninitialized in
if (score < computerScore)
or
score = score + card;
depending on the if(play == 0) or if(play == 1) condition.
It happens to have some junk as its memory content, the compiler does not initializes to zero for you. In fact, it is undefined behaviour to use un-initialized variables. Initialize it before the first usage, preferable in the definition itself,
int score = 0;
Also, compile with warnings on (-Wall -Wextra for g++/clang++), since the compiler will easily warn about these mistakes.

Answer 2

Try running this and seeing if you have the same issues. I just added some print statements to try and debug it, and it stopped showing me really big numbers..
EDIT:
//ADD
int score = 0;
//
if (play == 1)
{
cout << "printing in the PLAY = 1 "<< score << endl;
card = genRandInt(1, 11);
score = score + card;
cout << "Your score is: " << score << "\n";
}