无法使用>>运算符从文件中正确读取数据

Question

I have a data file with 3 columns in each row: Two 3 character strings and a float like this.

AAA BBB 699.25

I'm trying to read in the data using ifstream like this:

    ifstream input;

    char str1[3], str2[3];
    float num;

    input.open("data.txt");

    input >> str1 >> str2 >> num;
    cout << str1 << endl;
    cout << str2 << endl;
    cout << num << endl;

However the output I get with Clang is:

(blank)
BBB
699.25

Or Intel C++ this:

AAABBB
BBB
699.25

If I get the individual variables without multiple ">>" operators all works correctly. I'm guessing I don't understand how >> works and it's overwriting my data in the buffer as I push more into the array.

Answer 1

The string "AAA" is not three characters long. You have three visible characters and one non visible null character. This means to hold "AAA" you need four characters worth of storage. If you use a std::string this becomes a non issue as it takes care of things like this for you. Since you just have this tagged as C++ I would change char str1[3], str2[3]; to std::string str1, str2;