Question

我在文件中有少量数据，看起来像

新墨西哥州 50.9 10

这与每个州都重复，每当我用两个单词为其标题命中状态时，我的程序就会说ooops我们会在你的字符串中放入第一个单词，但第二个单词没有存储空间。因此，一旦遇到双重措辞的标题，它就会停止接收剩余的数据。有没有办法在读取我的文件时把两个单词放在一个字符串中？

#include <iostream>
#include <string> 
#include <fstream>
#include <cstring>
using namespace std;

struct AccountsDataBase{

    string stateName;
    double miles;
    int rests;

};

#define MAX 80

AccountsDataBase * account = new AccountsDataBase[MAX];


int readIn(ifstream& file){
    int count=0;    

    file >> account[count].stateName;
    file >> account[count].miles;
    file >> account[count].rests;


while( !file.eof() && count<MAX){

    count++;
    file >> account[count].stateName;
    file >> account[count].miles;
    file >> account[count].rests;




}    

    return count;
}




int main(){

   ifstream file;
   file.open("input.txt"); //opens data account records text

   if ( !file.fail() ) {
       int cnt = readIn(file);


       delete[] account;
   }


return 0;

}

Answer 1

你的问题肯定含糊不清。但是，这是一种方法：

std::ifstream ifile("filename_and_path"); //Requires <fstream>

//check to see if the file is open or not:
if (!ifile.is_open()) {
    std::cerr << "Something went wrong!" << std::endl;
    exit(1);//stop program execution. Requires <cstdlib>
}

std::string temp;
std::string state;
std::vector <std::string> tokens; //Requires <vector>

//std::getline requires: <string>
while(std::getline(ifile, temp)) {
    std::istringstream iss(temp);//initialize the stream to the contents of the line

    //keep parsing over the stream into tokens separated by ' ' (space) characters
    while(std::getline(iss, temp, ' ')) {
        //store all the tokens:
        tokens.push_back(temp);
    }

    //UPDATED to read ALL states. (I misread the question.)
    //we know that the last two parameters are always numbers, so use this
    //to our advantage:

    //if an even number, then we have two words, get and concatenate them:
    if (tokens.size() % 2 == 0) {
        state = tokens[0] + " " + tokens[1];
    }
    else {
        //this is an odd number of parameters. This means that this is a state
        //with one word (e.g.: Maryland)
        state = tokens[0];
    }

    //this is the end of one line, might as well print out the state name:
    std::cout << state << std::endl;
    state.clear();//empty the string for the next iteration
    tokens.clear();//empty the tokens for the next iteration
}

Answer 2

您可以使用std :: vector存储每行中的所有std :: string标记，然后使用迭代器读取值。只要文件中每行的最后两个标记代表double和int值，此解决方案适用于任何长度的一般状态名称，而不仅仅是像新墨西哥这样的双字的一个。

int readin(const ifstream& file)
{
  ...

  string val;  
  vector<string> v;

  while (val = file.get() )
  {
     v.push_back(val);     
  }

  //assign concatentaion from element 1st to nth-2
  for(vector<string>::iterator it = v.begin(), it != v.end()-2;it++)
     account[count].stateName += *it + " ";  

  //assign element nth -2
  account[count].miles = atof(*(v.end()-2).c_str());
  //assign element nth -1
  account[count].rests = atoi(*(v.end()-1).c_str());

 ...
}

Answer 3

好的每个人我都问我的老师答案，她说我所要做的就是使用getline（）; D解决我的问题，即将应用20行代码来解决单行C函数问题。

c ++ ifstream只读取一个字符串需要同时读入

3 个答案: