Visual Studios C ++代码中的错误。Lab4.obj：错误LNK2019：无法解析的外部符号“布尔__cdecl

我正在尝试创建一个程序，该程序对文件中的所有整数进行计数，并检查它们是否为偶数。而且，我不断收到与“检查它们是否均匀”部分相关的错误。这是我的代码：

#include<iostream>
#include<fstream>
#include<cstdlib>
#include<ctime>
#include <string>

using namespace std;

bool isNotEven(int&);

int main()
{
    ifstream myfile("input.txt");
    int numberTot = 0;
    int numberOdd = 0;
    int check = 1;
    string line;

    while(check != -1)
    {
        getline(myfile,line);
        check = stoi(line);

        if (check != -1)
            numberTot++;

        if (isNotEven(check) == true)
            numberOdd++;
    }

    cout << "There are " << numberTot << " numbers in this file." << endl;
    cout << "There are " << numberOdd << " odd numbers in this file." << endl;
    char x;
    cin >> x;
}

bool isNoteEven(int& x)
{
    if (x%2 == 0)
        return false;
    else
        return true;
}

我不断收到此错误，并且对为什么出现它感到困惑

1>  Lab4.cpp
1>Lab4.obj : error LNK2019: unresolved external symbol "bool __cdecl isNotEven(int &)" (?isNotEven@@YA_NAAH@Z) referenced in function _main
1>C:\Users\Nick\Desktop\CS1\Lab4\Debug\Lab4.exe : fatal error LNK1120: 1 unresolved externals