c++，对 ifstream 使用 get 和 >>

Question

我有一个要从中输入数据的文本文件，但我似乎无法正确输入数据。

下面是文本文件中的两行作为示例(这些不是真实的人不用担心):

Michael    Davidson     153 Summer Avenue        Evanston        CO 80303
Ingrid     Johnson      2075 Woodland Road       Aurora          IL 60507

这是我必须加载文本文件并将数据放入结构中的代码。我仍然是 C++ 的新手(很明显)，我很难同时使用 get 和 >>。我下面的代码在我进入“状态”之前工作正常，然后出现问题。感谢您的帮助!

//constants
const int FIRST_NAME_LEN = 11;
const int LAST_NAME_LEN = 13;
const int ADDRESS = 25;
const int CITY_NAME_LEN = 16;
const int STATE_LEN = 3;

//define struct data types
struct CustomerType {
    char firstName[FIRST_NAME_LEN];
    char lastName[LAST_NAME_LEN];
    char streetAddress[ADDRESS];
    char city[CITY_NAME_LEN];
    char state[STATE_LEN];
    int zipCode;
};

//prototype function
ifstream& getInfo(CustomerType& CT_Struct, ifstream& infile);

int main() {

    //declare struct objects
    CustomerType CT_Struct;

    ifstream infile("PGM951_customers.txt");
    if(!infile) {
        cerr << "Could not open the input file." << endl;
        exit(1); //terminates the program
    }

//call the function
getInfo(CT_Struct, infile);

return 0;
}

ifstream& getInfo(CustomerType& CT_Struct, ifstream& infile) {

    while(infile) {
        infile.get(CT_Struct.firstName, sizeof(CT_Struct.firstName));
        infile.get(CT_Struct.lastName, sizeof(CT_Struct.lastName));
        infile.get(CT_Struct.streetAddress, sizeof(CT_Struct.streetAddress));
        infile.get(CT_Struct.city, sizeof(CT_Struct.city));
        infile.get(CT_Struct.state, sizeof(CT_Struct.state));
        infile >> ws;
        infile >> CT_Struct.zipCode;    

        cout << CT_Struct.firstName << " | " << CT_Struct.lastName << " | " << CT_Struct.streetAddress  
            << " | " << CT_Struct.city << " | " << CT_Struct.state  << " | " << CT_Struct.zipCode << endl;
    }

return infile;

}

===编辑===========在 8 个字符的状态下阅读只是我在胡闹，然后我忘了将其改回...抱歉。

Answer 1

问题是 istream::get() 中断了 streetAddress，其中有空格。

一种方法是首先将输入行标记化为 strings 的 vector，然后根据标记的数量将这些转换为 的适当字段>客户类型:

vector<string> tokenize(string& line, char delim=' ') {
      vector<string> tokens;
      size_t spos = 0, epos = string::npos;
      while ((epos = line.find_first_of(delim)) != string::npos) {
          tokens.push_back(line.substr(spos, epos - spos));
          spos = epos; 
      }
      return tokens;     
}

我更喜欢 CustomerType 的流提取操作符:

struct CustomerType  {
   friend istream& operator>>(istream& i, CustomerType& c);
   string firstName, lastName, ...;
   // ...
};

istream& operator>>(istream& i, CustomerType& c) {       
   i >> c.firstName >> c.lastName;
   string s1, s2, s3;
   i >> s1 >> s2 >> s3;
   c.streetAddress = s1 + s2 + s3;  
   i >> c.city >> c.state >> c.zipCode;
   return i;
}