Trying to spawn a thread that doesn't accept this specific function

Question

Firsly, allow me to post my code:

#include "stdafx.h"
#include <iostream>
#include <iomanip>
#include <fstream>
#include <climits>
#include <thread>
#include <fstream>

using namespace std;

bool isPrime(int num) {
    if (num < 2)
        return false;
    if (num == 2)
        return true;
    if (num % 2 == 0)
        return false;
    for (int i = 3; (i*i) <= num; i += 2) {
        if (num % i == 0)
            return false;
    }
    return true;
}
ofstream out;
void fwrite(unsigned int toWrite) { //function to write the value on file
    out << toWrite << '\n';
}
void fprint(long double toPrint) { //function to print the percentage of the completion of the writing-on-file process
    cout << setw(8) << '\r' << (long double)toPrint / 100000000.0 * 100 << "%";
}

int main(){
    out.open("prime numbers from 5 to 100 millions");
    for(unsigned int i = 0; i <= 100000000; i++){
        if (isPrime(i)) {
            thread tprint(fprint,i); //works fine alone
            thread twrite(fwrite,i); //triggers intellisense and compile error
            tprint.join();
            twrite.join();
        }
    }
}

This program's purpose is to print and write to file all the prime numbers it can find, up to 100 millions. Printing and writing operations are done in two different threads. The functions resposible for this arefwrite and fprint.

If a prime number is found, thread tprint(fprint,i) is caled, and the current percentage of completion is printed without any problem. But if I use thread twrite(fwrite,i) I get these compiler errors.

E0289 no instance of constructor "std::thread::thread" matches the argument list <the path to the cpp file...>\infprime.cpp   line 37`

and

Severity  Code    Description Project File    Line    Suppression State
C2661 'std::thread::thread': no overloaded function takes 2 arguments <the path to the cpp file..>\infprime.cpp   line 37

I absolutely have no idea why thread tprint(fprint,i) works but thread twrite(fwrite,i) causes these errors.

Note: it is possible to get the same error w/o `using namespace std;`. If so, ping me and I will re-open. — juanchopanza, Aug 25 '17 at 05:44
But, you should really make this a [mcve]. Most of the code is irrelevant. — juanchopanza, Aug 25 '17 at 05:48
fwrite is the name of a c library function The complier can't resolve which function you want. Use a different name for your function and it will compile. — Michaël Roy, Aug 25 '17 at 05:49
@MichaëlRoy It's true that [`fwrite`](http://en.cppreference.com/w/cpp/io/c/fwrite) is a function inherited from the C standard, but it's not a vararg function. It has exactly four arguments. No more, no less. — Some programmer dude, Aug 25 '17 at 05:51
Yup. I stand corrected. Still I've tried with a different name, and it does compile. — Michaël Roy, Aug 25 '17 at 05:52

Trying to spawn a thread that doesn't accept this specific function

0 Answers0