error LNK2019: unresolved external symbol main referenced in function __tmainCRTStartup MSVCRTD.lib(crtexe.obj)

Katherine Johnson picture Katherine Johnson · Dec 16, 2012 · Viewed 16.3k times · Source

I keep receiving the following two errors and I can't figure out why.

error LNK2019: unresolved external symbol _main referenced in function ___tmainCRTStartup MSVCRTD.lib(crtexe.obj)

error LNK1120: 1 unresolved externals

Ensuring that I run it as Console [even in Linker Properties it says Console] I am using VC++ 2012 Ultimate. I'm not insanely technically oriented with jargon and advanced concepts so please try not to overwhelm me Dx.

//Main.cpp
#include <conio.h>
#include "XArray.h"


int Main() {
    XArray<int> Test;
    Test.Add(3);
    getch();
    return 1;
}

Followed by.

#ifndef XARRAY_H
#define XARRAY_H

template <class X>
class XIndex {
public:
    X Value;
    XIndex<X> *Next;

    //Construct
    XIndex(X ArrayValue) { Value = ArrayValue; Next = nullptr; }

};

template <class X>
class XArray {
    XIndex<X> *First;
public:
    //Construct/Destruct;
    XArray() { First = nullptr; }
    ~XArray();

    //Operators that Alter the structure;
    void Add(X); //Add X to the end.
    void AddX(X, int); //Create Int amount of X values
    void Insert(int, X); //Insert X at Index int
    bool Remove(int); //Remove Index int. Return true if deleted, false if failed.
    //void Sort(); //Todo -- Sorts by value.
    //Operators that deal with the values.
    X Get(int);
    void Set(int, X);


};

template <class X>
void XArray<X>::AddX(X NewVal, int Quantity) {
    for (int i = 0; i < Quantity; i++)
        Add(NewVal);
}

template <class X>
void XArray<X>::Add(X NewVal) {
    XIndex<X> *CurrentIndex;
    XIndex<X> *NewNode; //Where we store NewVal
    NewNode = new XIndex<X>(NewVal);

    //List doesn't exist.
    if (!First) { 
        First = NewNode;
    } else {
        //Start at beginning.
        CurrentIndex = First;
        while ((*CurrentIndex).Next){ 
            CurrentIndex = (*CurrentIndex).Next;
        }
        (*CurrentIndex).Next = NewNode;
    }

}

template <class X>
void XArray<X>::Insert(int Index, X NewVal) {
    XIndex<X> *CurrentIndex;
    XIndex<X> *PrevIndex;
    XIndex<X> *NewNode; //Where we store NewVal
    iCounter = 0;
    NewNode = new XIndex<X>(NewVal);

    //List doesn't exist.
    if (!First) { 
        First = NewNode;
    } else {
        //Start at beginning.
        CurrentIndex = First;

        while ((*CurrentIndex).Next != nullptr && iCounter < Index){ 
            iCounter += 1
            PrevIndex = CurrentIndex;
            CurrentIndex = (*CurrentIndex).Next;
        }
        if (PreviousNode == nullptr) {
            First = NewNode;
            (*NewNode).Next = CurrentIndex;
        } else {
            (*PrevIndex).Next = NewNode;
            (*NewNode).Next = CurrentIndex;
        }
    }

}

template <class X>
bool XArray<X>::Remove(int Index) {
    XIndex<X> *CurrentIndex;
    XIndex<X> *PrevIndex;
    int iCounter = 0;
    if (First == nullptr) return false; //We never had a list.

    //It's the first one;
    if (Index == 0) {
        CurrentIndex = (*First).Next;
        delete First;
        First = CurrentIndex;
        return true;
    }

    //Starting as normal.
    CurrentIndex = First;

    //Loop until we reach the index.
    while (CurrentIndex != nullptr && iCounter < Index) {
        iCounter += 1
        PrevIndex = CurrentIndex;
        CurrentIndex = (*CurrentIndex).Next;
    }
    if (CurrentIndex != nullptr) {
        (*PrevIndex).Next = (*CurrentIndex).Next;
        delete CurrentIndex;
        return true;
    }
    return false;

}

//Destructor;
template <class X>
XArray<X>::~XArray() {
    XIndex<X> *NextIndex;
    XIndex<X> *CurrentIndex;

    //Start at beginning.
    CurrentIndex = First;

    //So long as we aren't at the end [when Next = nullptr];
    while (CurrentIndex != nullptr) {
        NextIndex = (*CurrentIndex).Next;
        delete CurrentIndex;
        CurrentIndex = NextIndex;
    }
}
#endif

Answer

prazuber picture prazuber · Dec 16, 2012

In C++ main function is declared as int main() or int main(int argc, char *argv[]) (see C++ Standard, paragraph 3.6.1 Main function).

In your case linker can't find the body of main, so it throws an error.