Empty character constant in c++

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 the tutorial was in VS 2008, and I am using VS 2013, so perhaps this is no longer valid, but I can't find any fix.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.

3 Answers

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.

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;

You've said that you "get an error stating that strncpy is unsafe to use if i use the null terminator," but you use strlen, which simply does not work if the string isn't null terminated. From cplusplus:

The length of a C string is determined by the terminating null-character

My suggestion to you would be to use null or 0 like others are suggesting and then just use strcpy instead of strncpy as you copy the whole string every time anyways.