Error Fstream

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Fstream Error Handling

Business Learn more about hiring developers or posting ads with us Stack Overflow Questions ofstream error Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, fstream open error just like you, helping each other. Join them; it only takes a minute: Sign up How to get error message when ifstream open fails up vote 39 down vote favorite 7 ifstream f; f.open(fileName); if (

C++ Ifstream Error Handling

f.fail() ) { // I need error message here, like "File not found" etc. - // the reason of the failure } How to get error message as string? c++ error-handling stream std share|improve this question edited Mar 7 '14 at 2:28 lpapp 35.4k134766 asked Jun 27 '13 at 7:51 0123456789 24.1k2191156 2 possible duplicate of C++ ifstream Error Checking –Matthieu Rouget Jun 27 '13 at 8:19 1 possible duplicate of Can

Ifstream::failure

you get a specific error condition when a C++ stream open fails? –arne Jun 27 '13 at 8:28 3 @Alex Farber: Sure. cerr << "Error code: " << strerror(errno); // Get some info as to why seems relevant to the question. –Matthieu Rouget Jun 27 '13 at 8:28 @MatthieuRouget: Check the possible duplicate I posted -- it seems this is non-standard behaviour only implemented by gcc. –arne Jun 27 '13 at 8:29 @MatthieuRouget: strerror(errno) works. Post this as answer, I will accept it. –0123456789 Jun 27 '13 at 8:37 add a comment| 3 Answers 3 active oldest votes up vote 30 down vote accepted Every system call that fails update the errno value. Thus, you can have more information about what happens when a ifstream open fails by using something like : cerr << "Error: " << strerror(errno); However, since every system call updates the global errno value, you may have issues in a multithreaded application, if another system call triggers an error between the execution of the f.open and use of errno. Edit (thanks to Arne Mertz and other people in the comments): e.what() seemed at first to be a more C++-idiomatically correct way of implementing this, however the string returned by this function is implementation-dependant and (at least in G++'s libstdc++) this fun

here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack ofstream fail Overflow the company Business Learn more about hiring developers or posting ads with us

Ifstream::failbit

Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a ifstream open fail community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up When will ofstream::open fail? up vote 10 down vote favorite 2 I am trying out http://stackoverflow.com/questions/17337602/how-to-get-error-message-when-ifstream-open-fails try, catch, throw statements in C++ for file handling, and I have written a dummy code to catch all errors. My question is in order to check if I have got these right, I need an error to occur. Now I can easily check infile.fail() by simply not creating a file of the required name in the directory. But how will I be able to check the same for outfile.fail() (outfile http://stackoverflow.com/questions/5835848/when-will-ofstreamopen-fail is ofstream where as infile is ifstream). In which case, will the value for outfile.fail() be true? sample code [from comments on unapersson's answer, simplified to make issue clearer -zack]: #include using std::ofstream; int main() { ofstream outfile; outfile.open("test.txt"); if (outfile.fail()) // do something...... else // do something else..... return 0; } c++ share|improve this question edited Apr 29 '11 at 19:01 Robᵩ 82.5k677143 asked Apr 29 '11 at 18:25 Scranton 51113 add a comment| 3 Answers 3 active oldest votes up vote 14 down vote The open(2) man page on Linux has about 30 conditions. Some intresting ones are: If the file exists and you don't have permission to write it. If the file doesn't exist, and you don't have permission (on the diretory) to create it. If you don't have search permission on some parent directory. If you pass in a bogus char* for the filename. If, while opening a device file, you press CTRL-C. If the kernel encountered too many symbolic links while resolving the name. If you try to open a directory for writing. If the pathname is too long. If your process has too many files open already. If the system has too many files open already. If the pathname refers to a device

mask for the stream. The second form (2) sets a new exception mask for the stream and clears the stream's error http://www.cplusplus.com/reference/ios/ios/exceptions/ state flags (as if member clear() was called). The exception mask is an internal value kept by all stream objects specifying for which state http://askubuntu.com/questions/561685/fatal-error-fstream-no-such-file-or-directory-when-uploading-code-to-arduino flags an exception of member type failure (or some derived type) is thrown when set. This mask is an object of member type iostate, which fstream error is a value formed by any combination of the following member constants: iostate value (member constants)indicatesfunctions to check state flags good()eof()fail()bad()rdstate() goodbitNo errors (zero value iostate)truefalsefalsefalsegoodbit eofbitEnd-of-File reached on input operationfalsetruefalsefalseeofbit failbitLogical error on i/o operationfalsefalsetruefalsefailbit badbitRead/writing error on i/o operationfalsefalsetruetruebadbit eofbit, failbit and badbit are member constants with implementation-defined fstream error handling values that can be combined (as if with the bitwise OR operator), so that the stream throws when any of the selected error state flags is set. goodbit is zero, indicating that no exceptions shall be thrown when an error state flags is set. All streams have goodbit by default (they do not throw exceptions due to error state flags being set). Parameters except A bitmask value of member type iostate formed by a combination of error state flag bits to be set (badbit, eofbit and/or failbit), or set to goodbit (or zero). Return Value The first form (1) returns a bitmask of member type iostate representing the existing exception mask before the call to this member function. Example 1
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// ios::exceptions #include // std::cerr #include // std::ifstream int main () { std::ifstream file; file.exceptions ( std::ifstream::failbit | std::ifstream::badbit ); try { file.open ("test.txt"); while (!file.eof()) fi

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 answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Ask Ubuntu Questions Tags Users Badges Unanswered Ask Question _ Ask Ubuntu is a question and answer site for Ubuntu users and developers. 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 top "fatal error: fstream: No such file or directory: when uploading code to Arduino up vote 2 down vote favorite I am trying to upload this code to my Arduino Yun in Ubuntu and I keep getting this error: Arduino: 1.5.8 (Linux), Board: "Arduino Yún" Build options changed, rebuilding all Using library FileIO in folder: /home/djloulou/Arduino/libraries/FileIO (legacy) /home/djloulou/arduino-1.5.8/hardware/tools/avr/bin/avr-g++ -c -g -Os -w -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -MMD -mmcu=atmega32u4 -DF_CPU=16000000L -DARDUINO=158 -DARDUINO_AVR_YUN -DARDUINO_ARCH_AVR -DUSB_VID=0x2341 -DUSB_PID=0x8041 -DUSB_MANUFACTURER= -DUSB_PRODUCT="Arduino Yun" -I/home/djloulou/arduino-1.5.8/hardware/arduino/avr/cores/arduino -I/home/djloulou/arduino-1.5.8/hardware/arduino/avr/variants/yun -I/home/djloulou/Arduino/libraries/FileIO /tmp/build8511320611227460765.tmp/sketch_dec01a.cpp -o /tmp/build8511320611227460765.tmp/sketch_dec01a.cpp.o In file included from yun_datalogger.ino:31:0: /home/djloulou/Arduino/libraries/FileIO/FileIO.h:12:19: fatal error: fstream: No such file or directory #inclu