Prueba 3

#include <iostream>
#include <stdlib.h>
#include <iomanip>
#include <math.h>
using namespace std;
void serie(int);
long double e(int);
long double factorial(int);
long double pi(int);
void cedula(int);
int i,j;

int main(int argc, char** argv) {
    int opc,x;
    double y,z;
    cin>>opc;

    switch (opc){
        case 1:
            cout<<"Ingrese haste que numero desea calcular la serie: "<<endl;
            cin>>x;
            serie(x);
        break;
        case 2:
            cout<<"Con que presicion desea calcular el nnumero e: "<<endl;
            cin>>x;
            cout<<fixed<<setprecision(7);
            cout<<e(x)<<endl;
        break;
        case 3:
            cout<<"Ingrese su numero de cedula: "<<endl;
            cin>>x;
            cedula(x);
        break;
        case 4:
            cout<<"Con que presicion desea calcular el nnumero e: "<<endl;
            cin>>x;
            cout<<fixed<<setprecision(7);
            cout<<pi(x)<<endl;
        break;
        default:
            cout<<"Opcion incorrecta"<<endl;
    }
    return 0;
}

void serie (int a){
    int b,c,d;
    b=1,c=1,d=0;
    for (i=0;i<a;i++){
        d=b+c;
        cout<<b<<" ";
        b=c;
        c=d;
    }
}

long double e(int a){
    long double cte=0;
    for (j=0;j<=a;j++){
        cte=cte+(1/factorial(j));
    }
    return cte;
}

long double factorial (int a){
    int total=1;
    for (i=1;i<=a;i++){
        total=total*i;
    }
    return total;
}

void cedula (int x){
int cedula,ced,pares,impares,total,dec=0;
    int a,b,c,d,e,f,g,h,i,j,k;
    cedula=x;
    ced=cedula;
    a=cedula/1000000000;
    cedula=cedula-(a*1000000000);
    b=cedula/100000000;
    cedula=cedula-(b*100000000);
    c=cedula/10000000;
    cedula=cedula-(c*10000000);
    d=cedula/1000000;
    cedula=cedula-(d*1000000);
    e=cedula/100000;
    cedula=cedula-(e*100000);
    f=cedula/10000;
    cedula=cedula-(f*10000);
    g=cedula/1000;
    cedula=cedula-(g*1000);
    h=cedula/100;
    cedula=cedula-(h*100);
    i=cedula/10;
    cedula=cedula-(i*10);
    j=cedula/1;
    cedula=cedula-(j*1);
    //cout<<cedula<<endl<<a<<endl<<b<<endl<<c<<endl<<d<<endl<<e<<endl<<f<<endl<<g<<endl<<h<<endl<<i<<endl<<j<<endl;
    if (cedula>2400000000){
        cout<<"El numero de cedula: "<<ced<<" es invalido."<<endl;
    }else{
        pares=b+d+f+h;
        a=a*2;
        if (a>9){
            a=a%10+a/10;
        }
        c=c*2;
        if (c>9){
            c=c%10+c/10;
        }
        e=e*2;
        if (e>9){
            e=e%10+e/10;
        }
        g=g*2;
        if (g>9){
            g=g%10+g/10;
        }
        i=i*2;
        if (i>9){
            i=i%10+i/10;
        }
        impares=a+c+e+g+i;
        total=pares+impares;
        while (dec-total!=j && dec<total+10){
            dec=dec+10;
        }
        if (dec-total==j){
            cout<<"El numero de cedula: "<<ced<<" es valido"<<endl;
        }else {
            cout<<"El numero de cedula: "<<ced<<" es invalido"<<endl;
        }
    }
}

long double pi(int c){
    long double var=4;
    double k=3;
    for (i=1;i<c;i++){
        var=var+pow(-1,i)*(4/k);
        k+=2;
    }
    return var;
}