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fstream error checking South Glastonbury, Connecticut

contact us Search: Reference ios bad public member function std::ios::bad bool bad() const;Check whether badbit is set Returns true if the badbit error state flag is set for So here is how to check for errors in ALL cases (i.e. if (!f.is_open()) perror(("error while opening file " + filename).c_str()); // Read the file via std::getline(). Extremely helpful, and Very easy to follow and understand.

This is not a serious software project. I was hoping that the new C++11 system_error library would provide a way to query this kind of error messages, but from what I've seen, you still have to pass errno Join them; it only takes a minute: Sign up Here's how it works: Anybody can ask a question Anybody can answer The best answers are voted up and rise to the I can see messages under Spy++ but nothing happens.

Good text editors always append a trailing new line. Also, one has to know when exactly it is safe to call perror() in the context of stream methods. Santosh In my c++ code I used is_open(), when I am running this code on Solaris 10 multi-core system I am facing issue. not only when badbit flag is set).

more hot questions question feed lang-cpp about us tour help blog chat data legal privacy policy work here advertising info mobile contact us feedback Technology Life / Arts Culture / Recreation It deals with all types of errors transparently. According to the test, one single problem may be identified via this method: a non-existing file. up vote 2 down vote favorite What's the correct way to check for a general error when sending data to an fstream?

error state: Success * skip operation on data, break loop ******** testing on valid file with one line content * trying to open and read: one_line_file error state after ifstream Also, if you want a line, use std::getline. –chris Nov 19 '12 at 1:38 Thanks for the link lightness –slowmotionfred Nov 19 '12 at 1:59 add a comment| 1 To read it you'd need to use the OS's primitives for reading directories - that's what "ls" is doing after all (and maybe open it in binary mode? Conclusion 1: When getline() on stream s has evaluated to False, i.e. !s and s.fail() are True, do not blindly use perror() to print an error message, because it is likely

Join them; it only takes a minute: Sign up fstream: the most correct way to check for errors up vote 0 down vote favorite I want to write a wrapper around Now assume an invalid file content "foo\nbar". And yes, I tested it by locking (in another program) a region of bytes in the file that getline() was reading. When it comes to the idea of providing meaningful error messages, things become quite complicated.

This occurs for instance when you try to read another line while you are already at EOF. Required: threadsafe and common to Windows and Linux (or at least Msvc/Gcc) -2 File wont open. 0 How to make ifstream follow symbolic link? 0 Having trouble opening a text file Discussed in the next part. Last edited on Oct 29, 2009 at 6:50am UTC Oct 29, 2009 at 2:23pm UTC cbouwkamp (84) Okay I took it out for now.

Moreover, you must explicitly ask for them in order to be thrown; otherwise, the default behavior is kept, that is querying the state of the stream. This is ancient. error state: Success * skip operation on data, break loop ******** testing on a file that is read by another process * trying to open and read: file_read error state Why is absolute zero unattainable?

Higher level in brake fluid tank after pad replacement Cyclically sort lists of mixed element types? more stack exchange communities company blog Stack Exchange Inbox Reputation and Badges sign up log in tour help Tour Start here for a quick overview of the site Help Center Detailed Error: Could not find a match for std::getline(std::ifstream, String) My code is as below: #include #include ifstream inActive; inActive.open(file); String finalLine; while (getline(inActive, finalLine)) { cout You can then do this: std::string lineFromFile; while(infile.fail() == false){ getline(infile, lineFromFile); /* Check things to do with the line */ std::cout << lineFromFile << std::endl; } You don't have to

error state: Permission denied * checking error bits once before first getline stream failbit (or badbit). Not the answer you're looking for? error state: Permission denied * skip operation on data, break loop ******** testing on a directory * trying to open and read: dir error state after ifstream constructor: Success is_open() error state: Success stream failbit (or badbit).

Why is it a bad idea for management to have constant access to every employee's inbox? Is 'if there's any' grammatical in this sentence? Reaching the End-of-File sets the eofbit. The goal is to process the data read from the file, line by line, via the fictitious call to process(line).

Also, if you construct the file stream object in the scope of the function, it will automatically be closed when it goes out of scope. Thanks in advance... goodbit is zero, indicating that none of the other bits is set. Only two rules, to follow -- isn't that easy?

The origin of these rules will become clearer while reading the rest of the article. That is, on POSIX-compliant systems errno/perror is thread-safe. While doing so, the goal was to handle all underlying stream errors as well as file opening errors, and to emit as precise error messages as possible. Exception safety Strong guarantee: if an exception is thrown, there are no changes in the stream.

As I think, that may be not enough. –ghostmansd Jul 5 '13 at 14:46 @ghostmansd None of the C++ stream functions throw exceptions. Of course there are many obvious and non-obvious ways to write unreliable code. giancan 88 posts since Oct 2011 Community Member SendMessage (vm_lbuttondown) trouble in VB.NET Last Post 14 Hours Ago I'm trying to develop some code to do a button click onto an You can read more about the functions that you can perform with std::strng here.

asked 3 years ago viewed 18212 times active 2 years ago Linked 39 How to get error message when ifstream open fails -2 Reading an int from a file in C++ Not the answer you're looking for? Theoretically should work equally well on Linux too since it relys only on what C/C++ language standard and library documentation says. I read a line from an ASCII file into a string using: ifstream paramFile; string tmp; //open input file tmp.clear(); paramFile >> tmp; //parse tmp How can I error check to

Jan-Philip Gehrcke I verified that your code works on Linux, after including . C++ Information Tutorials Reference Articles Forum Forum BeginnersWindows ProgrammingUNIX/Linux ProgrammingGeneral C++ ProgrammingLoungeJobs Home page | Privacy policy© cplusplus.com, 2000-2016 - All rights reserved - v3.1Spotted an error? My CEO wants permanent access to every employee's emails.