程序代码：

    ifstream infile ("D:\\xxxx\\Desktop\\xxxx.txt");
    if (!infile) {
        cout << "openfile error";
        return -1;
    }
    char ch;
    while (infile.get (ch) ) {
        if (ch != '\n')
            cout <<  ch << endl;
        else
            cout << "换行";
    }

    string str;
    while (getline (infile, str) ) {
        if (str.find ( "str" ) != -1)
            cout << "found str"; 
    }