How to use string class?

Question

Hi, experts:
Have you run HelloStrings sample in "Thinking in C++" book? The source code is following. But when I compile, it throws error:"string in not defined". How to write correct makefile? Thanks! /Denise
//: C02:HelloStrings.cpp
// The basics of the Standard C++ string class
#include <string>
#include <iostream>
using namespace std;
int main() {
string s1, s2; // Empty strings
string s3 = "Hello, World."; // Initialized
string s4("I am"); // Also initialized
s2 = "Today"; // Assigning to a string
s1 = s3 + " " + s4; // Combining strings
s1 += " 8 "; // Appending to a string
cout << s1 + s2 + "!" << endl;
} ///:~

Answer 1

The most likely cause is that the "using namespace std;" line is missing from the file you are compiling, or commented out.
Using C++ 5.6 and the exact file I listed earlier, I get this result:
% CC -V hello.cc
CC: Sun C++ 5.6 2004/06/02
/set/mercury/dist/fcs.2/sparc-S2/opt/SUNWspro/prod/bin/c++filt: Sun C++ 5.6 2004/06/02
ccfe: Sun C++ 5.6 2004/06/02
ld: Software Generation Utilities - Solaris Link Editors: 5.9-1.377
Copy/paste the hello.cc file I listed above and try compiling it.
If you still get errors, your compiler was not installed correctly, or the installation has become corrupted.
If you want to poke around a bit more before re-installing, try this:
CC -H -c HelloStrings.cc |& grep string
The -H option lists all the header files that were read. You should see this, assuming your compiler is installed in /opt:
/opt/SUNWspro/prod/include/CC/Cstd/./string <------- string header
     /opt/SUNWspro/prod/include/CC/std/string.h
          /usr/include/string.h
               /usr/include/iso/string_iso.h
     /opt/SUNWspro/prod/include/CC/Cstd/rw/string_ref
If in particular you do not see /opt/SUNWspro/prod/include/CC/Cstd/./string, or if the "string" header marked above comes from some other location, something is definitely wrong with the compiler installation.
If you see the correct string header, run "wc" on that header. You should see this:
1858 6099 68105 string
If not, the string header is corrupted.
To re-install, refer to the Installation Guide that comes with Sun Studio 9. Follow the instructions for uninstalling Sun Studio 9. Then run the product installer, paying close attention to any warnings or error messages. I strongly recommend using the product installer, and not trying to install the product yourself directly from the packages.