从C ++中的文本文件中读取有向图的邻接列表 [英] Read adjacency list of digraph from a text file in C++

问题描述

我有一个文本文件，每行都有一些整数.示例:

I have a text file which has some number of integers in each line. Example:

1 2 4
3 
0 4

2 3

第1行表示第一个节点已连接到编号为1、2和5的节点.空行表示第4个节点未与任何节点连接.

Here 1st line means that the 1st node is connected to nodes numbered 1, 2 and 5. Blank line means 4th node isn't connected to any node.

这给了我一个有向图. 此SO问题可能会有所帮助，但它假设每行包含2个整数，而在这种情况下，它可以具有从0到N-1(N是节点数)的任意数量的整数.

This gives me a directed graph. This SO question might have been helpful but it assumes each line to have 2 integers, whereas in this case it can have any number of integers from 0 to N-1(N is no. of nodes).

我只想知道如何阅读此文本文件.如果每行有两个整数，则可以完成infile >> a >> b.如何知道发生"\ n"或行尾. 我不是要求提供可生成有向图的代码.

I just want to know how to read this text file. If I had two integers per line, I could have done infile >> a >> b. How to know that "\n" or end of line has occured. I am not asking for code that makes directed graph.

推荐答案

我不认为这是家庭作业，因为主要主题是有向图.

I do not think that this is homework, since the acutal topic are digraphs.

因此有一些代码.但是，您必须自己处理错误.

Therefore some code. But, you have to do the error handling yourself.

#include <string>
#include <iostream>
#include <fstream>
#include <sstream>
#include <vector>

typedef std::vector<int> nl_t;
typedef std::vector<nl_t> nll_t;

int main()
{
    std::ifstream is("test.dat");
    std::string str;

    nll_t nll;

    while(std::getline(is,str)) {
        std::istringstream ss(str);
        nl_t nl;
        int i;

        while(ss >> i) {
            nl.push_back(i);
        }
        nll.push_back(nl);
    }
}
/**
     Local Variables:
     compile-command: "g++ -g test.cc -o test.exe; ./test.exe"
     End:
*/

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