Question

when would getline in c++ fail?

I have a big snippet of code which I am unable to paste in its entirety for multifarious reasons. I am trying to read from a file , which I know exists and contains data, using getline in C++. But getline fails returning error 123-invalid name(output of getlasterror). I looked up the error code which baffles me even more.

I do error check while opening the file. So I am positive that I have the handle to the file.
Please bear with me for not pasting the code. I am new to c++ and especially in windows. Any suggestions or insights about getline would help. I am trying to read a file which is dumped by a compiler.

This is an extract from the code

ifstream inFile("C:\...\ash.txt",ios::in);

string singleLine;

getline(inFile,singleLine);

singleLine is empty ! I am doing something silly..pls point that out to me! appreciate it

IMPORTANT EDIT:

I checked for the ios members and found that fail bit is set. Why would the fail bit be set? the file does exist and also I was wondering if how windows exposes file extensions could cause a problem . That doesnt seem to the problem. What am i missing?

Answer 1

If the fail bit is set, it is probably because you didn’t successfully open the file. Check whether ifFile.is_open() returns true; if not, then then probably indicates that the file is not open correctly. You might not have permissions, or you may need to escape the string properly, or the file may be locked.

You should also check if fail is set both before and after the call to getline. If it’s before, that probably means that the file isn’t open. If it’s after, it could mean that the file is empty.

It may be the case that Windows is hiding the true file extension from you. The file name might actually be named ash.txt.txt, for example, if you have Explorer configured to hide file extensions. That might be worth investigating if the file isn’t open.