C2440 error in BitArray template class

[natekelsey]

Ok so I've spent quite a bit on this and I'm at a loss as to what to do. I've gone over my code and everything looks to be fine. This is currently incomplete. Anyways does anyone have any clues as to how to fix these two errors:

'return' : cannot convert from 'BitArray<size_t>' to 'BitArray<size_t>'
'initialize' : cannot convert from 'BitArray<size_t>' to 'BitArray<size_t>'

This error pops up in my each of my shift operations and in my slice function (depending on what test function is being called)Any ideas would be appreciated
The lines that end with an E are the ones that get the error
tbitarray.h

// tbitarray.cpp: A cursory test for the BitArray class
#include <iostream>
#include <sstream>
#include <stdexcept>
#include <string>
#include "bitarray.h"
#include "test.h"
using namespace std;

// Test program
int main() {
	// Test exceptions
	BitArray<> b;
	//throw_(b[0], logic_error);
	//throw_(b.toggle(0), logic_error);
	//const BitArray<> b1{ b }; // Test copy constructor
	//throw_(b1[0], logic_error);

	// Test empty Bitarray properties
	test_(b.size() == 0);
	test_(b.count() == 0);
	test_(b.capacity() == 0);
	test_(!b.any());

	// Validate construction and to_string()
	BitArray<> b2{ 5 };
	test_(b2.size() == 5);
	for (size_t i = 0; i < 5; ++i) {
		test_(!b2[i]);
	}
	test_(b2.to_string() == "00000");

	// Test copy, assign, equality, and from_string
	BitArray<> b3{ b2 };
	test_(b2 == b3);
	test_(b != b2);
	test_(!b3[2]);
	b3[2] = 1;
	test_(b3[2]);
	test_(b2 != b3);
	test_(b2.to_string() == "00000");
	b = b2;
	test_(b.to_string() == "00000");

	// Test move operations
	BitArray<> b4{ move(b3) };
	test_(b4[2]);
	BitArray<> b4b;
	b4b = move(b4);
	test_(b4b[2]);

	// Test bit ops
	BitArray<> x{ "011010110" }; // Also tests string constructor
	test_(x.count() == 5);
	test_(x.any());
	//test_((x << 6).to_string() == "110000000");	E
	//test_((x >> 6).to_string() == "000000011");	E
	//test_((x <<= 3).to_string() == "010110000");	E
	//test_((x >>= 3).to_string() == "000010110");	E
	//BitArray<> y{ ~x };							E
	nothrow_(x.toggle());
	//test_(x == y);
	//test_(x.to_string() == "111101001");

	b = BitArray<>{};
	test_(!b.any());
	b += 1;
	b += 0;
	b += 1;
	test_(b.to_string() == "101");
	test_(b.any());

	b2 = BitArray<>{ "10101011" };
	test_(b2.count() == 5);
	b2.toggle();
	test_(b2.to_string() == "01010100");
	//b2.erase(3);
	//test_(b2.to_string() == "0100100");
	//b2.erase(b2.size() - 1);
	//test_(b2.to_string() == "010010");
	//b2.erase(1, 4);
	//test_(b2.to_string() == "00");
	//b2.insert(1, 1);
	//test_(b2.to_string() == "010");
	//b2.insert(1, 0);
	//test_(b2.to_string() == "0010");
	//b2 += b;
	//test_(b2.to_string() == "0010101");
	//b2.insert(3, b);
	//test_(b2.to_string() == "0011010101");

	ostringstream os;
	os << "101" << 'a' << "0101";
	istringstream is{ os.str() };
	b3 = BitArray<>{};
	is >> b3;
	test_(b3.to_string() == "101");
	is.get();
	is >> b3;
	test_(b3.to_string() == "0101");
	os.str("");
	os << 'a';
	istringstream is2{ os.str() };
	is2 >> b3;
	test_(!is2);
	test_(b3.to_string() == "0101");

	BitArray<> b5{ "11111111111111111111111111000000000000000000000000000011" };
	//test_(b5.slice(23, 10) == BitArray<>("1110000000"));	E
	//size_t n = b2.size();
	//b2.insert(3, b5);
	//test_(n + b5.size() == b2.size());
	//b2.erase(3, b5.size());
	b2.shrink_to_fit();

	//// Test comparisons
	BitArray<> b6{ "10101" };
	BitArray<> b7{ "101010" };
	BitArray<> b8{ b7 };
	test_(b6 < b7);
	test_(b6 <= b7);
	test_(b6 <= b6);
	test_(b7 > b6);
	test_(b7 >= b6);
	test_(b7 >= b7);
	test_(BitArray<>("111") > BitArray<>("10111"));

	BitArray<> b9{ "11111111111111111111111111000000000000000000000000000011" };
	ostringstream ostr;
	ostr << b9;
	test_(ostr.str() == "11111111111111111111111111000000000000000000000000000011");
	test_(b9.count() == 28);
	//nothrow_(b9 <<= 2);									E
	//test_(b9.count() == 26);
	//nothrow_(b9 >>= 33);									E
	//test_(b9.count() == 23);
	BitArray<> b10{ "01" };
	//b9[0] = b10[0] = b10[1];
	//test_(b10[0]);
	//test_(b9[0]);
	const BitArray<> b11{ b10 };
	//test_(b11[0]);

	//BitArray<> b12("11011111101");
	//b12.erase(1, 8);
	//test_(b12.to_string() == "101");
	//b12 += b12;
	//test_(b12.to_string() == "101101");

	BitArray<> b13("");
	test_(b13.size() == 0);

	report_();
	cin.get();
}

/* Output (should have at least 4 move assignments):
move constructor
move assignment
move assignment
move assignment
move assignment
move assignment
move assignment
shrinking from 2 to 1 words   (numbers may vary)
Test Report:
Number of Passes = 69
Number of Failures = 0
*/

[natekelsey]

bitarray.h

#ifndef BIT_ARRAY_H
#define BIT_ARRAY_H

#include <vector>
#include <climits>
#include <stdexcept>
#include <string>
#include <math.h>
#include <iostream>
#include <utility>

using std::vector;
using std::string;
using std::cout;
using std::endl;
using std::ostream;
using std::istream;
using std::logic_error;

template<class IType = size_t>
class BitArray
{
private:
	vector<IType> Bit_Vector;
	size_t _count;
	enum { BITS_PER_WORD = CHAR_BIT* sizeof(IType) };
	bool test(size_t pos) const
	{
		return Bit_Vector[pos / BITS_PER_WORD] & (1u << (pos%BITS_PER_WORD));
	}
	void reset(size_t pos) 
	{
		Bit_Vector[pos / BITS_PER_WORD] &= ~(1u << (pos%BITS_PER_WORD));
	}		
	void set(size_t pos)
	{
		Bit_Vector[pos / BITS_PER_WORD] |= (1u << (pos % BITS_PER_WORD));
	}		
	void copy(size_t pos, bool value) 
	{
		if (value)
			set(pos);
		else
			reset(pos);
	}
	bool readBit(size_t pos)const
	{
		size_t block = pos / BITS_PER_WORD;
		size_t offset = pos % BITS_PER_WORD;
		if (pos >= _count)
			throw logic_error("Index given is out of range.");
		else
			return Bit_Vector[block] & (1u << offset);
	}
	bool assignBit(size_t pos, bool value)
	{
		size_t block = pos / BITS_PER_WORD;
		size_t offset = pos % BITS_PER_WORD;
		if (value)
			Bit_Vector[block] |= (1u << offset);
		else
			Bit_Vector[block] &= ~(1u << offset);
	}
public:
	// Object Management
	explicit BitArray(size_t bitCount = 0)
	{
		_count = bitCount;
		if (bitCount)
			Bit_Vector.resize((bitCount - 1) / BITS_PER_WORD + 1);
	};
	explicit BitArray(const string& bit_string)
	{		
		_count = bit_string.length();
		if (_count)
			Bit_Vector.resize((_count - 1) / BITS_PER_WORD + 1);
		for (size_t i = 0; i < _count; ++i)
		{
			if (bit_string[i] == '1')
			{
				set(i);
			}
			else if (bit_string[i] == '0')
			{
				reset(i);
			}
			else
				throw runtime_error("0 or 1 not found");
		}
	};
	explicit BitArray(const BitArray& b) = default;		// Copy constructor
	BitArray& operator=(const BitArray& b) = default;	// Copy assignment
	explicit BitArray(BitArray&& b) noexcept : Bit_Vector(b.Bit_Vector)	// Move assignment
	{
		cout << "move constructor" << endl;
		_count = b._count;
		//Bit_Vector = b.Bit_Vector;
		b._count = 0;
		b.Bit_Vector.clear();
	};	
	BitArray& operator=(BitArray&& b) noexcept
	{
		cout << "move assignment" << endl;
		swap(_count, b._count);
		swap(Bit_Vector, b.Bit_Vector);
		return *this;
	};
	size_t capacity() const			
	{
		return (BITS_PER_WORD * Bit_Vector.size());
	};			
	// Append a bit
	BitArray& operator+=(bool bit)
	{
		//2 options space/no space
		if (capacity() == _count)
			Bit_Vector.resize(Bit_Vector.size() + 1);
		_count++;
		//put bit in last spot
		copy(_count - 1, bit);
		return *this;
	}
	//** Append a BitArray
	BitArray& operator+=(const BitArray& b)
	{
		// Add BitArray obj starting from the last spot of the current BitArray
		if (capacity() == _count)
			Bit_Vector.resize(Bit_Vector.size() + Bit_Vector.size());
		//Append BitArray obj to the end
		for (int i = 0; i < _count; i++)
		{
			copy(_count-1, b[i]);
			_count++;
		}
		return *this;
	}	
	//** Remove “nbits” bits at a position
	void erase(size_t pos, size_t nbits = 1)
	{
		????Bit_Vector[pos/BITS_PER_WORD] = nbits/BITS_PER_WORD;
	}	
	//** Insert a bit at a position (slide "right")
	void insert(size_t pos, bool value)
	{
		
	}	
	//** Insert an entire BitArray object
	void insert(size_t pos, const BitArray& bitArray)
	{

	}
	// Discard unused, trailing vector cells
	void shrink_to_fit()
	{
		if (!Bit_Vector[Bit_Vector.size() - 1])	//ask if it's a 0
		{
			Bit_Vector.resize((_count - 1) / BITS_PER_WORD + 1);
		}
	}	
	// Bitwise ops
	class bitproxy
	{
		BitArray* b;
		int pos;
	public:
		bitproxy(BitArray* bs, int p) : b(bs) {
			pos = p;
		}
		bitproxy& operator=(bool bit) {
			if (bit)
				b->Bit_Vector[pos/BITS_PER_WORD] |= (1u << (pos%BITS_PER_WORD));
			else
				b->Bit_Vector[pos / BITS_PER_WORD] &= ~(1u << (pos%BITS_PER_WORD));
			return *this;
		}
		operator bool() const {
			return b->Bit_Vector[pos / BITS_PER_WORD] & (1u << (pos%BITS_PER_WORD));
		}
	};
	friend class bitproxy;
	bitproxy operator[](size_t pos)
	{
		if (pos >= _count)
			throw logic_error("Invalid Index.");
		return bitproxy(this, pos);
	}
	bool operator[](size_t pos) const
	{
		if (pos>=_count)
			throw logic_error("Invalid Index.");
		else
			return test(pos);
	}
	// Toggles all bits
	void toggle(size_t pos)
	{
		if (test(pos))
			reset(pos);
		else
			set(pos);
	}	
	void toggle()	// toggles all bits
	{
		for (size_t i = 0; i < _count; ++i)
		{
			if (test(i))
				reset(i);
			else
				set(i);
		}
	}
	BitArray operator~() const
	{
		BitArray<> bitArray(*this);
		bitArray.toggle();
		return bitArray; // //ERROR :C2440	'return': cannot convert from 'BitArray<size_t>' to 'BitArray<size_t>'
	}
	// Shift operators…
	BitArray operator<<(unsigned int sLeft) const
	{
		BitArray<> bitArray(*this);
		return bitArray <<= sLeft;	//ERROR :C2440	'return': cannot convert from 'BitArray<size_t>' to 'BitArray<size_t>'

	}
	BitArray operator>>(unsigned int sRight) const
	{
		BitArray<> bitArray(*this);
		return bitArray >>= sRight;	//ERROR :C2440	'return': cannot convert from 'BitArray<size_t>' to 'BitArray<size_t>'
	}
	BitArray& operator<<=(unsigned int n) 
	{
		BitArray<> temp1 = slice(n, _count - n); //ERROR :C2440	'initializing': cannot convert from 'BitArray<size_t>' to 'BitArray<size_t>'
		BitArray<> temp2(n);
		temp1 += temp2; 
		*this = temp1;
		return *this;
	}	
	BitArray& operator>>=(unsigned int n)
	{
		BitArray<> temp1(n); 
		BitArray<> temp2 = slice(n, _count - n); //Error C2440	'initializing': cannot convert from 'BitArray<size_t>' to 'BitArray<size_t>'
		temp1 += temp2;
		*this = temp1;
		return *this;
	}
	
	BitArray slice(size_t pos, size_t count) const
	{
		string bitstr = (*this).to_string();
		BitArray b{ bitstr.substr(pos, count) };
		return b;		//Error C2440	'initializing': cannot convert from 'BitArray<size_t>' to 'BitArray<size_t>'
	}
	
	bool operator==(const BitArray& checkBits) const
	{
		return !((*this) < checkBits || checkBits > (*this));
	}	
	bool operator!=(const BitArray& checkBits) const
	{
		return ((*this) < checkBits || checkBits > (*this));
	}	
	bool operator<(const BitArray& checkBits) const
	{
		if (strcmp((*this).to_string().c_str(), checkBits.to_string().c_str()) < 0)
			return true;
		else
			return false;
	}
	bool operator<=(const BitArray& checkBits) const
	{
		if (strcmp((*this).to_string().c_str(), checkBits.to_string().c_str()) <= 0)
			return true;
		else
			return false;
	}	
	bool operator>(const BitArray& checkBits) const
	{
		if (strcmp((*this).to_string().c_str(), checkBits.to_string().c_str()) > 0)
			return true;
		else
			return false;
	}	
	bool operator>=(const BitArray& checkBits) const
	{
		if (strcmp((*this).to_string().c_str(), checkBits.to_string().c_str()) >= 0)
			return true;
		else
			return false;
	}
	size_t size() const 
	{
		return _count;
	}
	size_t count() const
	{
		size_t one_bits = 0;
		for (size_t i = 0; i < _count; ++i)
		{
			if (test(i))
				one_bits++;
		}
		return one_bits;
	}	
	bool any() const
	{
		//for loop through vector
		for (size_t i = 0; i < Bit_Vector.size(); i++)
		{
			if (Bit_Vector[i])
				return true;
		}
		return false;
	}
	friend ostream& operator<<(ostream& ostrm, const BitArray& _bitarray)
	{
		ostrm << _bitarray.to_string();
		return ostrm;
	}
	friend istream& operator>>(istream& istrm, BitArray& _bitarray)
	{
		string bitStr = "";
		char charChk;
		char charNext = 0;
		while (istrm >>charChk)
		{
			if (!isdigit(charChk))
			{
				charNext = -1;
				charNext = istrm.peek();
				istrm.unget();
				istrm.setstate(std::ios::failbit);
				break;
			}
			else
			{
				bitStr.push_back(charChk);
			}
		}
		if (charNext == -1)
			return istrm;
		istrm.clear();
		BitArray<> ba(bitStr);
		_bitarray = ba;
		return istrm;
	}
	string to_string() const 
	{
		string charStr = "";
		for (size_t i = 0; i < _count; i++)
		{
			if(test(i))
				charStr += '1'; //adding a 1
			else
				charStr += '0';	//adding a 0
		}
		return charStr;
	}
};

[MiiNiPaa]

BitArray<> temp1 = slice(n, _count - n); 
return bitArray <<= sLeft;

You disabled ability to perform copy initialization and to do implicit conversion yourself by declaring copy constructor explicit. No wonder that those lines are rejected.

Hint: never declare copy constructor explicit. There is literally no reason to do so.