i need to know how to use powers in c++. so if i enter to and then 3 for the power i get 8.

this is what i have so far

``````#include <iostream>
using namespace std;

double power(double,int);

int main()
{
double n;
int p;
cout << "Enter a number ";
cin >> n;
cout << "Enter a power ";
cin >>p;
cout << power(n,p);
return 0;
}

double power(double n, int p)
{

}``````

the function power is the part im having problems with i dont know what to put in it

Have you tried multiplying p n times? Do you know about loops yet?

It's called using a flow chart. Draw one for the code (presuming it works) and all should become clear.

Trace each step with your finger and write the results on paper.

## All 8 Replies

Have you tried multiplying p n times? Do you know about loops yet?

``````double power( double n, int p )
{
double result = 1.0;
for(int j=0; j<p; j++)
result *= n;
return result;
}``````

ok i got the loop i just dont understand it can some one explain it quick

It's called using a flow chart. Draw one for the code (presuming it works) and all should become clear.

Trace each step with your finger and write the results on paper.

>ok i got the loop i just dont understand it
Translation: I ganked this code, but I need to know how it works to get credit for my homework. ;)

>can some one explain it quick
What don't you understand? It's a simple loop that counts p times and continually updates the result by multiplying n into it.

You might, for the sake of clarity, want to chage

``result *= n;   to  result = result * n;``

>You might, for the sake of clarity, want to chage
>result *= n; to result = result * n;
Why? It's not like this is a huge stumbling point for beginners.

LOL not really ganked and its not for a class. but i did find the code in the back of the book.

well maybe ganked just a little =P

``````double power( double n, int p )
{
double result = 1.0;
for(int j=0; j<p; j++)
result *= n;
return result;
}``````

Suppose you send the value of n = 2 and power as 3 ie. p=3

Then the loop runs 3 times.
Each time it runs the result is multiplied by 2.

result = result * n;

This statement is executed p times multiplying the result with n.
This is how the power function works.

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