--Originally published at Solving problems with programming

In this homework what we had to do is ask for the user for 10 numbers, save them, display them and with all of them calculate the avegrage and the standart deviation. To start with we need to use an array. An array is a variable that can save multiple variables. How they work is like the other variables , you need to specify that is a variable.

float array[10];

This means that the variable in the array are going to be floating point and the [10], means that the array is going to consist of 10 variables, you can save 10 numbers in that array.

To fill data in the array, you do it like with any other variable.

 cin>>array[0];

But in the arrays you need to spicify wich variable of the 10 spaces you created, you are going to save. In This code i’m saying that i’m gong to enter variable of the first spot. In arrays you start counting the spots from 0. Being that have 10 spots y can enter variables from the spot 0 to the spot 9.

So at the beggining of the program i wil ask for 10 variables. I’m going to use a for loop to enter all these variables in my array. The key here is to change the spot of what i’m entering to my array, every repetition i’m going to enter the next spot available in my array.

 
for(int i=0;i<10;i++){
 cout&lt;&lt;"Escribe tu valor "&lt;<i+1<<endl;
 cin&gt;&gt;array[i];

The other important information we need for this program, is to calculate the sanadart deviation. I didn’ what it was but in this page I understood it excellent. To get the standart deviation you also need arrays, but I’ll let you think how to do it. Anyway if there is any problem I let

--Originally published at Solving problems with programming

This homework was a little bit more dificult for me at the biggining, i didn’t understand what was a recursion and how did they work. I wrote it just because a web page said how, but I didn’t understand how it worked. After analizing it finally i understood .

A recursion is the call of the same function that is being defined at that moment. You can define a function and at the same time use it inside that function. It is confusing to understand and to explain also hahaha, but in the code and by doing the exercise you could understarnd it.

int factorial(int n){
int resultado;
if(n>0)
resultado=n*factorial(n-1);
else if(n==0)
resultado=1;
return resultado;

I will simulate an exucution of this function. If n=2, n is bigger than 0 so, we will multiply n by the factorial of n-1 that equals 1. So the factorial of 1 is  1 multiply by the factorial of 1-1 that equals 0. So the factorial of 0 is 1, because that is said on the function, if(n==0) resultado=1. So 2*1*1 gives 2.

Here is all the code

#include <iostream>
using namespace std;
int factorial(int n){
int resultado;
if(n>0)
resultado=n*factorial(n-1);
else if(n==0)
resultado=1;
return resultado;
}
main(){
int num, res;
char op;
do{
cout<<“Escribe el número que desea convertir en factorial”<<endl;
cin>>num;
res = factorial(num);
if(res==0)
cout<<“No se puede sacar el factorial a numeros negativos “<<endl;
else{
cout<< “El número factorial es “<<res<<endl;
}
cout<<“¿Quieres calcular otro número factorial?(S/N)”;
cin>>op;
if(op==’N’||op==’n’)
cout<<“Ten un lindo día”<<endl;
}while(op==’S’||op==’s’);
return 0;
}

I also solve the factorial number with loops do while and for, that are easier to make. The code is linked if you like to take a look.