const char* c;
string s="1234";
c = s.c_str(); 
cout<<c<<endl; //輸出：1234
s="abcd";
cout<<c<<endl; //輸出：abcd

//const char* c; //①
//char* c;       //②
//char c[20]; 
char* c=new char[20];
string s="1234";
//c = s.c_str(); 
strcpy(c,s.c_str());
cout<<c<<endl; //輸出：1234
s="abcd";
cout<<c<<endl; //輸出：1234

// basic_string_copy.cpp
// compile with: /EHsc /W3
#include <string>
#include <iostream>

int main( )
{
    using namespace std;
    string str1 ( "1234567890" );
    basic_string <char>::iterator str_Iter;
    char array1 [ 20 ] = { 0 };
    char array2 [ 10 ] = { 0 };
    basic_string <char>:: pointer array1Ptr = array1;
    basic_string <char>:: value_type *array2Ptr = array2;

    cout << "The original string str1 is: ";
    for ( str_Iter = str1.begin( ); str_Iter != str1.end( ); str_Iter++ )
        cout << *str_Iter;
    cout << endl;

    basic_string <char>:: size_type nArray1;
    // Note: string::copy is potentially unsafe, consider
    // using string::_Copy_s instead.
    nArray1 = str1.copy ( array1Ptr , 12 );  // C4996
    cout << "The number of copied characters in array1 is: "
        << nArray1 << endl;
    cout << "The copied characters array1 is: " << array1Ptr << endl;

    basic_string <char>:: size_type nArray2;
    // Note: string::copy is potentially unsafe, consider
    // using string::_Copy_s instead.
    nArray2 = str1.copy ( array2Ptr , 5 , 6  );  // C4996
    cout << "The number of copied characters in array2 is: "
        << nArray2 << endl;
    cout << "The copied characters array2 is: " << array2Ptr << endl;

    ////注意一定要使array3有足夠的空間
    //char array3[5]={0};
    //basic_string<char>::pointer array3Ptr=array3;
    //basic_string<char>::size_type nArray3;
    //nArray3 = str1.copy(array3,9); //錯(cuò)誤！?。?！
    //cout<<"The number of copied characters in array3 is: "
    //  <<nArray3<<endl;
    //cout<<"The copied characters array3 is: "<<array3Ptr<<endl;
}