Reading the file and storing into the class

Question

1.00/5 (1 vote)

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I am reading a text file where my inputs are as follows

date Fri Sep 1 02:11:40.195 pm 2017
base hex  timestamps absolute
internal events logged
// version 9.0.0
Begin Triggerblock Fri Sep 1 02:11:40.195 pm 2017
   0.000000 Start of measurement
   0.002893 1  201             Rx   d 8 06 0D 00 B0 89 00 0D E7  Length = 227925 BitCount = 118 ID = 513
   0.003133 1  280             Rx   d 8 1B 0C 7C F1 E8 75 39 67  Length = 221910 BitCount = 115 ID = 640
   0.003375 1  281             Rx   d 8 6B 0C 00 4E F4 07 8F 18  Length = 223925 BitCount = 116 ID = 641
   0.003623 1  282             Rx   d 8 DA 0C 23 FA 01 02 2C 04  Length = 227910 BitCount = 118 ID = 642

i need to make the file read from line 6 and store each of them into class variable and also should skip reading length,bitcount and ID

can anyone suggest me how i could set them

my class is as follows

C++

class data_Read
{
public:
	double time;
	unsigned int state;
	std::string  ID;
	std::string status;
	std::string type;
	unsigned int byte_lent = 8;
        std::string message[];

public:
	void readData(std::istream& is, data_Read& data);
};

and readdata function like this

void data_Read::readData(std::istream& is, data_Read& data)
{
	std::string line;

	for (int i = 0; i <= 5; i++)
	{
		std::getline(is, line);
	}
	
	while (std::getline(is, line))
	{
		std::istringstream iss(line);

		iss >> data.time;
		iss >> data.state;
		iss >> data.ID;
		iss >> data.status;
		iss >> data.type;
		
		for (int i = 1; i <= data.byte_lent; i++)
		{
			iss >> data.message[i];
		}
	}

	cout << data.time << "/t" << data.state << "/t" << data.ID << "/t" << data.status << "/t" << data.type << "/t" << data.message;
}

what changes i could do in order to get the output as i want

What I have tried:

i tried initialising line but did not work and giving loop to read first 5 lines and later next

Posted 7-Dec-17 22:28pm

Member 13475664

Updated 8-Dec-17 3:51am

Leo Chapiro

v2

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2 solutions

Solution 1

What do you get and what do you expect?

Also, why have you changed your message member to a std::string array instead of letting it an uint8_t array as used in your previous question Read and store array of hexadecimal data[^]?

The only problem I can see is that you forgot to read the message length byte_lent:

iss >> data.time;
iss >> data.state;
iss >> data.ID;
iss >> data.status;
iss >> data.type;
// Reading the length is missing in your code
iss >> data.byte_lent;
for (unsigned int i = 0; i < data.byte_lent; i++)
{
    // Read msg data bytes here
}

[EDIT: Clarifying]

Quote from (not a) solution:
and ignore 8 and length, bitcount and ID

If you want to ignore the length, you still have to read it from the stream. Otherwise, it will be read as first message data.

The remaining data after the message bytes are skipped by just not reading further from the stream buffer but processing the next line.
[/EDIT]

Posted 7-Dec-17 23:11pm

Jochen Arndt

Updated 7-Dec-17 23:35pm

v4

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CPallini · Accepted Answer · 2017-12-08T03:51:00

The following program

C++

#include <iostream>
#include <sstream>
#include <string>
#include <array>
#include <vector>
#include <iomanip>

using namespace std;

struct Data
{
  static constexpr size_t SIZE = 8;
  double time;
  int id;
  int status;
  string type;
  string dir;
  std::array<uint8_t, SIZE> d; 
  bool parse_line(const string & line);
};

ostream & operator << ( ostream & os, const Data & data);

int main()
{
  string line;
  vector <Data> v;

  while ( getline(cin, line) )
  {
    Data d;
    if ( d.parse_line(line) )
      v.push_back( d );
  }
  
  for (const auto & d : v)
    cout << d << endl;
}

ostream & operator << ( ostream & os, const Data & data)
{
  os << "time " << data.time << "\tid " << data.id << "\tstatus " << data.status << "\ttype " << data.type << "\tdir " << data.dir << "\tdata ";
  for (size_t n=0; n < Data::SIZE; ++n)
    os << setw(4) << static_cast<unsigned int>(data.d[n]);
  return os;
}

bool Data::parse_line( const string & line )
{
  istringstream iss(line);

  iss >> time;
  if ( ! iss ) return false;
  iss >> id;
  if ( ! iss ) return false;
  iss >> status;
  if ( ! iss ) return false;
  iss >> type;
  if ( ! iss ) return false;
  iss >> dir;
  if ( ! iss ) return false;

  int count;
  iss >> count;
  if ( ! iss ) return false;
  for ( size_t n= 0; n< SIZE; ++n)
  {
    size_t pos;
    string hex;
    iss >> hex;
    if (!iss) return false;
    d[n] = static_cast<uint8_t>( stoul(hex, &pos, 16));
    if ( pos != 2 ) return false;
  }
  return true;
}

fed with your input data (redirect it to get standrd iputfrom your file) produces the following output:

time 0.002893	id 1	status 201	type Rx	dir d	data    6  13   0 176 137   0  13 231
time 0.003133	id 1	status 280	type Rx	dir d	data   27  12 124 241 232 117  57 103
time 0.003375	id 1	status 281	type Rx	dir d	data  107  12   0  78 244   7 143  24
time 0.003623	id 1	status 282	type Rx	dir d	data  218  12  35 250   1   2  44   4