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C++ Discussion Thread
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Jul 9th, 2007

powers in c++

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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

C++ Syntax (Toggle Plain Text)
#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)
{
 
 }
#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

thank you in advance

Last edited by tralfas; Jul 9th, 2007 at 4:54 pm.

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tralfas

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Jul 9th, 2007

Re: powers in c++

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

Narue

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Jul 9th, 2007

Re: powers in c++

C++ Syntax (Toggle Plain Text)
double power( double n, int p )       
{
double result = 1.0; 
for(int j=0; j<p; j++)
result *= n; 
return result;       
}
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

Last edited by tralfas; Jul 9th, 2007 at 5:30 pm.

tralfas

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Jul 9th, 2007

Re: powers in c++

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.

iamthwee

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Jul 9th, 2007

Re: powers in c++

>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.

Narue

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Jul 9th, 2007

Re: powers in c++

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

(Toggle Plain Text)


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

iamthwee

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Re: powers in c++

>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.

Narue

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Jul 9th, 2007

Re: powers in c++

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

tralfas

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Jul 10th, 2007

Re: powers in c++

Click to Expand / Collapse Quote originally posted by tralfas ...

C++ Syntax (Toggle Plain Text)
double power( double n, int p )       
{
double result = 1.0; 
for(int j=0; j<p; j++)
result *= n; 
return result;       
}
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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