Issue with integer validation in Visual Studio 2017

After having studied some library functions cctypelike isdigite, isalphaI decided to create a program, inspired by some tutorials I saw on yt, to validate integers.

Below my code:

#include <iostream> 
#include <string>
#include <cctype>

using namespace std;

bool tipo_i_valido(string s);
int capturar_i();

int main()
{
    int numero;

    numero = capturar_i();
    cout << "El numero ingresado es: " << numero << "\n" << endl;

    return 0;
}

bool tipo_i_valido(string s)
{
    int i, longitud_s;

    longitud_s = s.length();

    if (longitud_s == 1)
    {
        if (!isdigit(s[0]))     
            return 0;       
    }
    else
    {
        if (s[0] == '+' || s[0] == '-' || isdigit(s[0]) != 0)
        {
            for (i = 1; i < longitud_s; i++)
            {
                if (!isdigit(s[i]))             
                    return 0;
            }
        }
        else
            return 0;       
    }
    return 1;
}

int capturar_i()
{
    int n_numero;
    string numero;
    bool es_valido;

    do {
        cout << "Ingrese un numero:\t";
        getline(cin, numero);
        cout << "\n";

        es_valido = tipo_i_valido(numero);

        if (!es_valido)
            cout << "ERROR. Ingrese solo numeros enteros.\n" << endl;
    } while (!es_valido);

    n_numero = stoi(numero);

    return n_numero;
}

As you can see, what I do is enter a string and if it turns out to be an integer including the sign, for example, +24or -12, then it considers it valid and the program converts the string using stoi. My problem is that for some reason in VS 2017, when I run my program, if I put the character ñthe program crashes and I get the following message: "debug assertion failed [...]". However, the code above, after compiling it to Dev C++ 5.11, runs as normal when executed.

Why is it that in VS the character ñcrashes my program, but in Dev C++ it doesn't?

Thanks in advance for your responses and/or comments.