can anyone show me a simple C++ example on lpc1768?

I have tried 3 days, switch compilers, linking scripts ...
to make a simple C++ program working on LPC1768 with G++, but failed.

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#include <iostream>

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#include <string>

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using namespace std;

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int main()

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{

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    std::string str = "foo";

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    std::cout << str << std::endl;

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    return 0;

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}

Anymore can show me the right version of cm3 files/linking scripts/gcc 
and ld option to make this program succeed return? I got this program 
compiled but hang while string assignment. And I need using G++ 
toolchains sourcery or yagarto or linaro with G++ version 4.6+.