How to read file and maintain file pointer in c++

Question

0.00/5 (No votes)

See more:

i have a txt file like this

name=abc
age=25
language=english
//blank line
name=def
age=55
language=hindi
//blank line

i have a structure in a class like this

C++

class Demo
{
public:
struct DATA
{
char* name;
char* Lang;
int age;
};
};

to read the file i use the following code
filestr is a filestream pointer and str is of type string

C++

while(!filestr.eof())
  {
      getline(filestr,str);

      cout<<str<<endl;
  }

What i want to do is:-
in read name value from file into structure filed name,age value in structure field age and lang value in lang field then pass the structure to the function and then again read the values in structure and pass the structure .

if its blank line leave it.Can you please help me to how to do this

Posted 7-Nov-12 3:40am

Tarun Batra

Add a Solution

3 solutions

Solution 1

It's easy. It seems that every line in your text file has two fields, key and value, except comment line(starts with "//").

You can read line to memory, then parse the key and value from line yourself(split the line to vector by "=", you can write a function to implement it), then check the key, and assign the value to your struct DATA

Key point: split every line to a vector by "=".

Posted 7-Nov-12 3:48am

icerlion

Updated 7-Nov-12 3:49am

v2

Comments

Tarun Batra 7-Nov-12 9:51am

Can you please give some pseudo code sir

Solution 3

Read this[^], and all the pages before it, and all the pages after it. Start making proper use of MSDN.

Posted 7-Nov-12 5:42am

Richard MacCutchan

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

icerlion · Accepted Answer · 2012-11-07T04:12:00

C++

// demo.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <fstream>
#include <string>
#include <iostream>
bool ParseLine(const std::string& line, std::string& key, std::string& value);

class Demo
{
public:
    typedef struct _Data 
    {
        std::string name;
        std::string email;
    } Data;

    Data data;
};

int main()
{
    std::ifstream ifs("d:\\demo.txt");
    std::string line;
    std::string key;
    std::string value;
    Demo obj;
    while(!ifs.eof())
    {
        std::getline(ifs, line);
        if (ParseLine(line, key, value))
        {
            if (0 == key.compare("name"))
            {
                obj.data.name = value;
            }
            else if (0 == key.compare("email"))
            {
                obj.data.email = value;
            }
            else
            {
                std::cerr<<"Unknow key:" << key << std::endl;
            }
        }
    }
    return 0;
}

bool ParseLine(const std::string& line, std::string& key, std::string& value)
{
    bool flag = false;
    if (line.find("//") != 0)
    {
        size_t pos = line.find("=");
        if (pos != std::string::npos)
        {
            key = line.substr(0, pos);
            value = line.substr(pos + 1, line.length());
            flag = true;
        }
    }
    return flag;
}
</iostream></string></fstream>

demo.txt:

VB

name=jhon
email=icerlion@163.com