Question

我想通过仅将id作为输入来搜索特定行如果id匹配文件中的id，它应该返回整行下面的代码显示文件中的整个数据应该是什么做一行。

我的代码如下：

void write_File()
{
      ofstream file;
      file.open ("example.txt");
      file << "Mobile Devices \n";
      file << "Name, MemorySize, Storage,    ScreenSize, NetworkAdapter, MultipleCameras, Microphones \n";
      file << " D01, \t 8GB, \t   32GB, \t4inches, \t Wifi, \t\t Yes, \t\t Yes \n";
      file << " D02, \t 8GB, \t   16GB, \t5inches, \t Wifi, \t\t No, \t\t Yes  \n";
      file << " D03, \t 16GB, \t   32GB, \t4.5inches, \t Wifi, \t\t Yes, \t\t No  \n";
      file << " D04, \t 32GB, \t   8GB, \t4inches, \t Wifi, \t\t No, \t\t Yes  \n";
      file << " D05, \t 64GB, \t   8GB, \t5.5inches, \t Wifi, \t\t Yes, \t\t Yes  \n";
      file << endl;
      file << "Personal Computer \n";
      file << "Name, MemorySize, Storage,    ScreenSize, PhysicalKeyboard, PointingDevices, DVDdrive, AdditionalPorts \n";
      file << " PC01, \t 8GB, \t   32GB, \t12inches, \t Yes, \t\t Yes, \t\t No, \t\t 2 \n";
      file << " PC02, \t 8GB, \t   16GB, \t14inches, \t Yes, \t\t No, \t\t Yes, \t\t 3 \n";
      file << " PC03, \t 16GB, \t   32GB, \t16inches, \t Yes, \t\t Yes, \t\t Yes, \t\t 1 \n";
      file << " PC04, \t 32GB, \t   8GB, \t14inches, \t Yes, \t\t No, \t\t No, \t\t 2 \n";
      file << " PC05, \t 64GB, \t   8GB, \t12inches, \t Yes, \t\t Yes, \t\t Yes, \t\t 3 \n";
      file << endl;

      file.close();
}
void read_File()
{
    string read;

    ifstream infile;
    infile.open ("example.txt");
        while(!infile.eof()) // To get you all the lines.
        {
            getline(infile,read); // Saves the line in STRING.
            cout<<read<<endl; // Prints our STRING.
        }
    infile.close();


}

Answer 1

你可以尝试类似的东西（添加评论）：

#include <iostream>
#include <fstream>
#include <string>
#include <limits>

void PrintLineWithId(std::string id)
{
    std::string read;
    std::ifstream infile("example.txt");

    while (infile)
    {
        if (std::getline(infile, read, ',')) // read beginning of the line until ,
        {
            if (read != id) // see if it matches id
                infile.ignore(std::numeric_limits<std::streamsize>::max(), '\n'); // doesnt match, skip to the next line
            else
            {
                // match
                infile.seekg(size_t(infile.tellg()) - read.length() - 1); // rewind to the line beginning
                std::getline(infile, read, '\n'); // read the whole line
                std::cout << read << std::endl; // print 
                return;
            }
        }
    }
}

int main()
{
    PrintLineWithId(" D05");
    return 0;
}

你必须分别处理id中的空格。

打印：

 D05,    64GB,     8GB,         5.5inches,       Wifi,           Yes,            Yes

从c ++

1 个答案: