将一个向量推入另一个向量

Question

I have a file that goes like this:

98
287 2352
987 4313 3253
235 34325 432 123

Basically I want to reproduce this file. I am trying to import a line at a time, extract the numbers, and push them into vectors. Each vector is pushed into a larger vector.

int main(int argc, char* argv[])
{
    int sum = 0, one = 0, two = 1;
    std::string line, number;
    std::vector<int> vec;
    std::vector<std::vector<int>> bigvec;
    auto k = vec.begin();
    std::ifstream in(argv[1]);
    while(in >> line) {
        std::istringstream is(line);
        while(is >> number) {
            vec.push_back(stoi(number));
        }
        bigvec.push_back(vec);
        while(!vec.empty()) {
            vec.pop_back();
        }
        std::cout << std::endl;
    }
    return 0;
}

My code though, when I print the result, seems to put each number in it's own vector instead of reproducing the file.

So my output is

98
287
2352
etc.

It seems that the line

while(is >> number) {
    vec.push_back(stoi(number));
}

pushes one number and then exits the loop.

Where am I going wrong?

Answer 1

Your problem lies here:

while(in >> line)

C++ by defult reads until it encounters interval or new line. In your case it encounters interval before new line. If you want to take the whole line take:

getline(cin, line);

Answer 2

while(in >> line) reads next word from the input. Use getline(in, line) if you want to read a whole line .

There are multiple optimizations that you can add to your code. For instance instead of using stoi on the string you've read you can read an integer from the input stream. Also instead of popping the vector's elements one by one you can simply call clear .