C++中string 与 char *赋值

#include <iostream>
#include <string>
#pragma warning(disable:4996)//vs弃用strcpy
int main() 
{
	using namespace std;
	string  input;
	cin >> input;
	int m_long;
	m_long = sizeof(input);//获取输入的长度
	char * m_input = new char[m_long];//动态分配内存空间
	strcpy(m_input, input.c_str());//string 赋值给char *
	cout << endl;
	cout << m_input << endl;
	cin.get();
	return 0;
}