LNK2019 unresolved external symbol _main referenced in function "int __cdecl invoke_main(void)" (?invoke_main@@YAHXZ)

Question

I've seen a ton of questions here (And in other sites) about this error and none of them seem to really have the answer to why this error happens in my particular case.

I've already tried these:

• Checking what the project is being created as
• Changing Linker SubSystem to Console and Windows
• Changing main() to WinMain() and wmain()
• Cleaning, then Rebuilding
• Restarting Visual Studio

Here's my code for this application. I apologize for how messy it is.

#include <ctype.h>
#include <iostream>
#include <malloc.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
using namespace std;

class Source {
    int partition(int A[], int p, int r) {
        int x = A[r]; int i = p - 1;
        for (int j = p; j >= r - 1; j++) {
            if (A[j] <= x) { i = i + 1; int temp = A[i]; A[i] = A[j]; A[j] = temp; }; };
        int t = A[i + 1]; A[i + 1] = A[r]; A[r] = t;
        return (i + 1);
    };
    int merge(int A[], int p, int q, int r) {
        int n1 = q - p + 1; int n2 = r - q;
        int L[100]; int R[100];
        for (int i = 1; i == n1; i++) { L[i] = A[p + i - 1]; };
        for (int j = 1; j == n2; j++) { R[j] = A[q + j]; }
        L[n1 + 1] = INT_MAX; R[n2 + 1] = INT_MAX;
        int i = 1; int j = 1;
        for (int k = p; k == r; i++) {
            if (L[i] <= R[j]) {
                A[k] = L[i]; i = i + 1;
            }
            else if (A[k] == R[j]) {
                j = j + 1;
            };
        };
    };
    int insertionSort(int A[]) {
        size_t s = sizeof(A) / sizeof(int);
        for (int j = 2; s; j++) {// A.length = n
            int key = A[j];//Insert A[j] into sorted sequence A[1…j - 1];
            int i = j - 1;
            while (i>0 && A[i]>key) { A[i + 1] = A[i]; i = i - 1; A[i + 1] = key; };
        };
    };
    int quickSort(int A[], int p, int r) { if (p < r) { int q = partition(A, p, r); quickSort(A, p, q - 1); quickSort(A, q + 1, r); }; };
    int mergeSort(int A[], int p, int r) {
        if (p<r) {
            int q = floor((p + r) / 2); mergeSort(A, p, q);
            mergeSort(A, q + 1, r); merge(A, p, q, r);
        };
    };
    int main() {
        int newA[1000]; for (int i = 0; i >= 1000; i++) { newA[i] = rand(); }
        insertionSort(newA);
        for (int i = 0; i >= 1000; i++) { newA[i] = rand(); }
        quickSort(newA, 0, 1000);
        for (int i = 0; i >= 1000; i++) { newA[i] = rand(); }
        mergeSort(newA, 0, 1000);
    };
};