ccsun2 :c-course % cat -n string.cpp
     1  //string.cpp
     2  ///by tsaiwn@csie.nctu.edu.tw
     3  #include<iostream>
     4  #include<string>
     5   //////// 以上要新版 C++ 才能用 !!!
     6  ////////  C++ 字串 不同於 C
     7  /////////// 以下是 C 的東東
     8  extern "C"{
     9     #include<stdio.h>
    10     #include<string.h>
    11  }
    12  using namespace std; ////////////// all LIB now in "std" namespace
    13  int main()
    14  {   char t[80];
    15      string x("I am a string.");
    16      cout << "x=" << x << endl;
    17      cout << "do strcpy(t, x.c_str() );" << endl;
    18      strcpy(t, x.c_str() );   //轉成 C 的字串
    19      printf("t=%s\n", t);
    20      printf(" length of t=%d\n", strlen(t));
    21      string y(t);  // 再轉成 C++ 字串看看
    22  
    23      cout << "do  string y(t);  " << endl;
    24  
    25      cout << "C++ String y=" << y << endl;
    26      cout << "it's size= y.size() = " << y.size() << endl;
    27  
    28      cout << " y = y + \" Do you get it?\";  " << endl;
    29  
    30      y = y + " Do you get it?";
    31  
    32      cout << "new y=" << y << endl;
    33      cout << "new size=" << y.size() << endl;
    34  }
ccsun2 :c-course % g++ string.cpp
ccsun2 :c-course % ./a.out
x=I am a string.
do strcpy(t, x.c_str() );
t=I am a string.
 length of t=14
do  string y(t);  
C++ String y=I am a string.
it's size= y.size() = 14
 y = y + " Do you get it?";  
new y=I am a string. Do you get it?
new size=29
ccsun2 :c-course % exit
exit