string类的data() 和c_str()区别

 1 #include <string>
 2 #include <iostream>
 3 #include <string.h>
 4 #include <stdio.h>
 5 
 6 using namespace std;
 7 
 8 int main()
 9 {
10     string s = "123 456";
11     size_t l1 = s.length();
12     size_t l2 = s.size();
13     const char* p1 = s.data();
14     const char* p2 = s.c_str();
15     cout << l1 <<" "    << l2 << " "<< p1 << " "    << p2 << " "     <<endl;
16     cout <<" sizeof( p1 )" << sizeof( p1 ) <<endl;
17     cout << " strlen( p1 ) " << strlen(p1) <<endl;
18     cout <<" sizeof( p2 )" << sizeof( p2 ) <<endl;
19     cout << " strlen( p2 ) " << strlen(p2) <<endl;
20     cout << "p1 = " << p1 << "\np2 = "<<p2 <<endl; 
21     printf("p1 = %p \n p2 = %p \n",p1,p2);
22     return 0;
23 }