read a file line by line in c++

[Piotr]

I have a qestion about reading file in C++.

How can I read a file line by line (i.e. putting a line ends wtih \n in
a string)

I tried the following, it does read the file, but it does not read it
line by line.

ifstream infile (fileName.c_str());
string buffer;
while ( infile >> buffer) {
cout << "a line: " << buffer << endl;
//BlockData bd(buffer);
// bd.dump();
}

Is there a file reading library in c++?

 

[Victor Bazarov]

I have a qestion about reading file in C++.

How can I read a file line by line (i.e. putting a line ends wtih \n in
a string)

See 'std::getline' function.

I tried the following, it does read the file, but it does not read it
line by line.

ifstream infile (fileName.c_str());
string buffer;
while ( infile >> buffer) {
cout << "a line: " << buffer << endl;
//BlockData bd(buffer);
// bd.dump();
}

Is there a file reading library in c++?

You're using it.

V

 

[HappyHippy]

I have a qestion about reading file in C++.

How can I read a file line by line (i.e. putting a line ends wtih \n in
a string)

I tried the following, it does read the file, but it does not read it
line by line.

ifstream infile (fileName.c_str());
string buffer;
while ( infile >> buffer) {
cout << "a line: " << buffer << endl;
//BlockData bd(buffer);
// bd.dump();
}

Is there a file reading library in c++?

You'll want to take a look at std::getline

std::ifstream inFile(...);
std::string sLine;
....
while(std::getline(inFile, sLine))
{
//Do here whatever you need to do
}

-HappyHippy

 

[Andre Kostur]

I have a qestion about reading file in C++.

How can I read a file line by line (i.e. putting a line ends wtih \n in
a string)

I tried the following, it does read the file, but it does not read it
line by line.

ifstream infile (fileName.c_str());
string buffer;
while ( infile >> buffer) {

Reads from infile until the first whitespace, so you're probably getting
your file, word by word. Look up std::getline().

 

[xPy]

the lines also end with a '\r' try a ( '\n' | | '\r' ) and also include
somewhere the "infile.eof()"
use this if you are using buffer.get(infile) (reads the file letter
by letter) or else '\n' will not work...

 

[BobR]

Piotr wrote in message

I have a qestion about reading file in C++.
How can I read a file line by line (i.e. putting a line ends wtih \n in
a string)
[snip code]

Is there a file reading library in c++?

The OP has been answered, but, I thought I'd throw this in and see what y'all
thought of it (..since y'all wrote it (if it looks like something you posted,
you may have)).

// -----------------------------------------------------------------
// Filer.h
// -----------------------------------------------------------------
#ifndef Filer_H
#define Filer_H
// ----------------------------------------------
#include <iostream>
#include <ostream> //std::endl
#include <string>
#include <vector>
// --------------------------------------
#include <stdexcept>
class MyError : public std::runtime_error { public:
MyError(const std::string &msg = "") : std::runtime_error(msg){}
};
// --------------------------------------

class Filer : public std::vector<std::string> {
public:
// Filer(){}
Filer(const char *filename){ Open(filename); }
private: // public: if I use Filer() Ctor, re-use instance, concat files.
void Open(const char *filename) throw(MyError){
std::ifstream in(filename);
if(!in){
throw MyError(__FILE__": Open SonOfABitch!");
} //if(!in)
for( std::string line; std::getline(in, line); ){ // [1]
push_back(line);
} //for()
return;
} //Open(const char*)
public:
void Write(std:stream& out = std::cout){
if(!out){
throw MyError(__FILE__": Write SonOfABitch!");
} //if(!in)
for(const_iterator w = begin(); w != end(); ++w)
out << *w << std::endl;
return;
} //Write(ostream&)
};
// --------------------------------------
#endif //#ifndef Filer_H
// -----------------------------------------------------------------END

// -----------------------------------------------------------------
// FilerTest.cpp
// -----------------------------------------------------------------
#include <iostream>
#include <ostream> //std::endl
#include "Filer.h"

int main(){
using std::cout;
try{
cout<<"_____ Filer.h _____"<<std::endl;
Filer Afile("Filer.h");
//Filer Afile("ErrFiler.h"); // to test exception.
Afile.Write(cout);
cout<<"Afile.size()="<<Afile.size()<<" lines."<<std::endl;
cout<<"Afile.at(1)="<<Afile.at(1)<<std::endl;
Afile.clear();
cout<<"Afile.size()="<<Afile.size()<<" lines."<<std::endl;
cout<<"_____ Filer.h End _____"<<std::endl;
}
catch(MyError &x){
cout<<"MyError &x.what()="<< x.what() <<std::endl;
} //catch(MyError&)
catch(...){
cout<< "DID NOT CATCH MyError()" <<std::endl;
} //catch(MyError&)
return 0;
} //main()
// -----------------------------------------------------------------END

"Filer.h" is a work-in-progress, so, don't hold back on the crit's. <G>
I've heard it's not a good idea to inherit from std container classes, but,
this seems to work. Good || bad? Was that advice for some other condition?
One objective of "Filer.h" is: KISS!

[1] Andrew Koenig, Walter Brown.