Empty character constant in c++

Question

I copied this code from a tutorial to play around with, however I kept on getting an error that stated that I can't have any empty character constants. the tutorial was in VS 2008, and I am using VS 2013, so perhaps this is no longer valid, but I can't find any fix. here is the code:

#include "stdafx.h"
#include <iostream>

class MyString
{
private:
    char *m_pchString;
    int m_nLength;

public:
MyString(const char *pchString="")
{
    // Find the length of the string
    // Plus one character for a terminator
    m_nLength = strlen(pchString) + 1;

    // Allocate a buffer equal to this length
    m_pchString = new char[m_nLength];

    // Copy the parameter into our internal buffer
    strncpy(m_pchString, pchString, m_nLength);

    // Make sure the string is terminated
    //this is where the error occurs
    m_pchString[m_nLength-1] = '';
}

~MyString() // destructor
{
    // We need to deallocate our buffer
    delete[] m_pchString;

    // Set m_pchString to null just in case
    m_pchString = 0;
}

    char* GetString() { return m_pchString; }
    int GetLength() { return m_nLength; }
};

int main()
{
    MyString cMyName("Alex");
    std::cout << "My name is: " << cMyName.GetString() << std::endl;
    return 0;
} 

The error I get is the following:

Error   1   error C2137: empty character constant       

Any help will be greatly appreciated

Thanks again.

Answer 1

This line:

m_pchString[m_nLength-1] = '';

What you probably mean is:

m_pchString[m_nLength-1] = '\0';

Or even:

m_pchString[m_nLength-1] = 0;

Strings are zero terminated, which is written as a plain 0 or the null character '\0'. For double quote strings "" the zero termintation character is implicitly added to the end, but since you explicitly set a single character you must specify which.

Answer 2

what do you think about null-terminated string? Yes, you are right, such strings must be terminated with null:

m_pchString[m_nLength-1] = 0;