[newbie] error C2065: 'b' : undeclared identifier

jon 80

Any idea why this code doesn't compile?

// SieveOfErathostenes.cpp : main project file.

#include "stdafx.h"
#include <bitset>
#include <iostream>
#include <ctime>

using namespace System;

int main(array<System::String ^> ^args)
{
const int N = 2000000;
clock_t cstart = clock();

bitset<N + 1> b;
int count = 0;
int i;
for (i = 2; i <= N; i++)
    b.set(i);
i = 2;

while (i \* i <= N)
{
    if (b.test(i))
    {
        count++;
        int k = 2 \* i;
        while (k <= N)
        {
            b.reset(k);
            k += i;
        }
    }
    i++;
}

while (i <= N)
{
    if (b.test(i))  count++;
    i++;
}

clock\_t cend = clock();
double millis = 1000.0 \* (cend - cstart) / CLOCKS\_PER\_SEC;

cout << count << " primes \\n" << millis << " milliseconds\\n";

return 0;

}

Errors: Error 4 error C2065: 'b' : undeclared identifier c:\Users\Administrator\Documents\Visual Studio 2008\Projects\SieveOfErathostenes\SieveOfErathostenes\SieveOfErathostenes.cpp 19 SieveOfErathostenes Error 5 error C2228: left of '.set' must have class/struct/union c:\Users\Administrator\Documents\Visual Studio 2008\Projects\SieveOfErathostenes\SieveOfErathostenes\SieveOfErathostenes.cpp 19 SieveOfErathostenes Error 6 error C2065: 'b' : undeclared identifier c:\Users\Administrator\Documents\Visual Studio 2008\Projects\SieveOfErathostenes\SieveOfErathostenes\SieveOfErathostenes.cpp 24 SieveOfErathostenes Error 7 error C2228: left of '.test' must have class/struct/union c:\Users\Administrator\Documents\Visual Studio 2008\Projects\SieveOfErathostenes\SieveOfErathostenes\SieveOfErathostenes.cpp 24 SieveOfErathostenes Error 8 error C2065: 'b' : undeclared identifier c:\Users\Administrator\Documents\Visual Studio 2008\Projects\SieveOfErathostenes\SieveOfErathostenes\SieveOfErathostenes.cpp 30 SieveOfErathostenes Error 9 error C2228: left of '.reset' must have class/struct/union c:\Users\Administrator\Documents\Visual Studio 2008\Projects\SieveOfErathostenes\SieveOfErathostenes\SieveOfErathostenes.cpp 30 SieveOfErathostenes Error 10 error C2065: 'b' : undeclared identifier c:\Users\Administrator\Documents\Visual Studio 2008\Projects\SieveOfErathostenes\SieveOfErathostenes\SieveOfErathostenes.cpp 39 SieveOfErathostenes Error 11 error C2228: left of '.test' must have

CPallini

Probably you get errors because are in the wrong forum (better luck here [^], maybe). :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles]

Stuart Dootson

The first error I get is this:

a.cpp(14) : error C2065: 'bitset' : undeclared identifier

This is because you use bitset without prefixing it with std::, which is the namespace it lives in. Similarly, cout needs a std:: prefix, because that's where it lives. [edit]Fix those two, and your code compiles fine. It runs as well.[/edit]

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

jon 80

Resolved that by including 'using namespace std;'. Now it reads: C1010 - unexpected eof. Says it needs a header file, but I "forgot" what to include. Afiak the header file includes: #pragma once ... ...and the headers of the methods used in my case... int main... However, it's strange that the default template created by visual studio with a main method did not require a .header file.

// SieveOfErathostenes.cpp : main project file.

#include <bitset>
#include <iostream>
#include <ctime>

using namespace System;
using namespace std;

int main(array<System::String ^> ^args)
{
const int N = 2000000;
clock_t cstart = clock();

std::bitset<N + 1> b;
int count = 0;
int i;
for (i = 2; i <= N; i++)
    b.set(i);
i = 2;

while (i \* i <= N)
{
    if (b.test(i))
    {
        count++;
        int k = 2 \* i;
        while (k <= N)
        {
            b.reset(k);
            k += i;
        }
    }
    i++;
}

while (i <= N)
{
    if (b.test(i))  count++;
    i++;
}

clock\_t cend = clock();
double millis = 1000.0 \* (cend - cstart) / CLOCKS\_PER\_SEC;

cout << count << " primes \\n" << millis << " milliseconds\\n";

return 0;

}

Sieve.h
#pragma once
#include <iostream>

int main(array<System::String ^> ^args);