'stoi' was not declared in this scope

[mscarfo]

In int main(), I am getting the error message "stoi was not declared in this scope." Is there a way around using stoi? Thanks!






#include <iostream>

#include <iomanip>

#include <vector>

#include <cmath>

#include <algorithm>

#include <string>

#include <ctime>

#include <cstdlib>

#include <iterator>

using namespace std;

vector<int> vec(1);

class isprime

{

public:

isprime();

bool operator() (int);

private:

int num;

};

isprime::isprime()

{

vec.push_back(2);

}

bool isprime::operator()(int num)

{

//sort the vector so that we can apply binary search

sort(vec.begin(), vec.end());

//use binary search to get iterator

bool ans = binary_search(vec.begin(), vec.end(), num);

if (ans) {

return true;

}

if (num < 2) {

return false;

}

for (int i = 2; i <= sqrt(num); i++) {

if (num%i == 0) {

return false;

}

}

vec.push_back(num);

return true;

}

struct random{

int operator()() {

int num = 0;

//this will return number between 0 and 99 both inclusive

num = rand() % 100;

if (num == 0)

num = 100;

return num;

}

}GetRandom;

int main(int argc, char *argv[]) {

int N = 10, i;

isprime pcheck;

//check if commandline argments have been provided

if (argc >= 2) {

N = stoi(argv[1]);

}

//set seeding to generate random numbers

srand(time(0));

//declare vectors of size N

vector<int> vec_random(N);

vector<bool> result(N);

//push numbers in a vector

generate(vec_random.begin(), vec_random.end(), GetRandom);

//use transform function to generate a boolean vector indicating whether a number is prime or not

transform(vec_random.begin(), vec_random.end(), result.begin(), pcheck);

cout << "Sequence contains " << count(result.begin(), result.end(), 1) << " prime numbers." << endl;

return 0;

}

[Peter87]

You could use std::istringstream. It allows you to read values and do error handling the same way as with std::cin.

std::istringstream iss(argv[1]);
iss >> N;

[Ganado]

I'm going to guess you're on MinGW. Upgrade your compiler instead, newest versions of MinGW should have this fixed.

PS: You never set num inside your isprime class to anything. I would just delete the variable.