CODEWITHSUNDEEP
c++math
Philipp Braun
Philipp Braun

Reputation: 1573

Simple math function not working

I am pretty new to c++ but I am trying to set up a really simple c++ project. Below you can find the code so far. But what I am having trouble with is the math function p = n^2-8n+7;. Any suggestions how I could improve it??

#include <iostream>
#include <stdio.h> 
using namespace std;

int main() {

/* Variable Declaration */
int p,n,i;

for (n=0; n<100; n++) {

/* Math Function */
p = n^2-8n+7;

/* Check if prime */
for (i=2; i<p; i++) { 
    if (!(p%i)) break;
    else cout << "(" << n << "," << p << ");" << endl;
}

}

/* Ready */
printf("\n\n\a");
system("pause");
}

Upvotes: 0

Views: 1753

Answers (3)

parapura rajkumar
parapura rajkumar

Reputation: 24433

You need to change

 n^2-8n+7;

to 

p = n * n - 8 *n + 7;

You are missing the * for multiplication and also instead of ^ you either need to mutliply two times or use pow function

Upvotes: 8

ATaylor
ATaylor

Reputation: 2598

The operator ^ is not equal to potency, but rather the binary operator 'XOR'.

For n^2 either use (n*n) or, for higher potencies, the premade 'pow' function, which is described here: http://www.cplusplus.com/reference/clibrary/cmath/pow/

For your example, that would be pow(n, 2); 8n doesn't work either, you need to write it fully as '8 * n'.

Upvotes: 5

PermanentGuest
PermanentGuest

Reputation: 5341

To get square use n*n instead of n^2. ^ is the bitwise xor operator.

Upvotes: 6

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