Funções legais

#include <iostream>
#include <cmath>

using namespace std;

double sum_pi(int n) {
  return (pow((-1),n))/((2*n)+1);
}

double pinto(int tamanho){
  double r = 0;
  for (int c=0; c<=tamanho; c++){
    r += sum_pi(c);
    }
  return(4*r);
}

double factorial(int n) {
  double result = 1.0;
  for (int c; c <= n; c++) {
    result *= c;
  }
  return result;
}

double sum_e(int x, int n){
  double result = (pow(x,n))/factorial(n);
  return result;
}

void e(int x){
  cout << exp(x) << endl;
  double result = 0;
  for (int c = 1; c <= 100; c++){
    result += sum_e(x,c);
    cout << result << " | ";
    if (!(c % 10)){
        cout << endl;
    }
  }
}

int main(){
  while(true){
    cout << "Type qualquer porra: ";
    long int tamanho;
    cin >> tamanho;
    e(tamanho);
  }
  return 0;
}