"Expression cannot seek vector iterator after end " - c++

Question

I am trying to make a very simple memory game and i'm having the following problem with vectors.
Expression cannot seek vector iterator after end
here is my code
#include <iostream>
#include <vector>
#include <algorithm>
#include <random>
using namespace std;
void play();
void filler();
char faceup(int);
vector<char> cards (50);
int candy= 0;
int main()
{
filler();
play();
}
char faceup(int C) {
return cards[C];
}
void play() {
int n,l;
char p, s;
for (int i = 0; i < cards.size(); i++)
{
cout << cards[i];
}
cout << endl;
while (candy<50)
{
cout << "choose first card"<<endl;
cin >> n;
cout << "choose second card"<<endl;
cin >> l;
if (l == n) {
cout << "the cards are the same, try it again"<<endl;
}
else
{
p = faceup(n);
s = faceup(l);
cout << "The first card is: " + p;
cout << "The second card is: " + s;
if (s==p)
{
candy++;
cards.erase(cards.begin()+s);
cards.erase(cards.begin() + p);
}
}
}
}
void filler() {
//random_device rd;
//default_random_engine rng(rd());
int accountant = 0;
for (int i = 0; i < cards.size()/2; i++)
{
for (int o = 0; o < 2; o++) {
cards[accountant] = i+65;
accountant++;
}
}
//shuffle(cards.begin(), cards.end(), rng);
}
the error occurs with any integer that I type. I used the compiler of visual studio, then i used dev c++. In all cases I got the same or similar error
Thanks a million in advance

Answer 1

In your code, in line 11, you defined a vector whose length is equal to 50, and if we give our vector a number outside the numbers 0 to 49, the program should not run.
That you encountered the error I mentioned above in lines 48 and 49 of your program.
For example, if the user enters his card number 0 and 1, the sizes s and p are equal to 66, and lines 48 and 49 say to go to our vector index 66, which creates a problem for running our program.
enter code here
//////////error/////////////////////////
cards.erase(cards.begin()+s);
cards.erase(cards.begin() + p);
//////////error/////////////////////////