why in cocos2dx ifstream failed json parse jsoncpp

hi ,all:
I met a question.
when I use the following code to read from a file I can get successed.
but when I use the same code in cocos2dx ,the code cannot open the file so I cannot parse the json string in the file(I use the jsonCpp to parse the json and I think it has nothing to do with the problem)

here is the code i used
@ ifstream infile;

infile.open (“test.json”, ifstream::in);

int ch = infile.get();
while (infile.good()) {
cout << (char) ch;
ch = infile.get();
cout<<“aaaa”<<endl;
}

infile.close();@