I have a C++ code I am running in Linux with wine. I think this is actually part of the problem.
Usually, when I do something like this in a native Linux C++ program:
ofstream fout;
fout.open("myfile.txt")
fout<<"blah blah"<<endl;
fout<<"blah blah 2"<<endl;
fout.close;
The file is standard ASCII text. However, in the code I an running under wine, myfile.txt is now ASCII text with CRLF line terminators.
This is a problem because if I want to read the file using a native Linux C++ code running on the same machine, the CRLF line terminators really mess up a lot of the file handling and parsing.
Is there a way to get the code running under wine to output files without CRLF line terminators and in a fashion that I can read it using the native Linux C++ code on the same machine?
You could open the file in ios::binary mode. This doesn't, strictly speaking, mean that it's a binary file [any more than any other file is "text", since all files are binary]. Binary in this context just means "don't muck about with the stuff inside the file by interpreting characters as special, add or remove any characters, etc.
Or when you copy the file to Linux, use dos2unix myfile.txt to convert it from "dos" (and Windows) format to "unix" style text file.
Related
I want to use ifstream::getline to read lines from a file, but the file contains the byte Ctrl-Z (0x1A), which makes getline think that it's reached the end of file (this is in Windows -- in *nix it would be Ctrl-D, if I'm not wrong). Can I disable this behaviour somehow, and tell getline to ignore Ctrl-Z?
Just for info: the file is comments.wast in the WebAssembly testsuite, which tests the ability of a WebAssembly parser to accept any and all characters inside a block comment.
This shouldn't happen when your ifstream object is using binary mode.
Just create it like this:
std::ifstream fin(<path>, std::ios::binary)
This of course prevents you from using other features of the stream, but if your main goal is to be able to read all sort of values while ignoring special characters, this is probably the way to go.
I'm trying to create a Fortran code for defining processor id. I can write the processor id into a text file. The text file pid2.txt is created but I can not read it in Fortran. While I open the text file in notepad or NotePad++ everything seems OK! In Fortran when I opening the text file it shows unknown parameter. Can any body help me with this problem?
The content of text file is
ProcessorId
BFEBFBFF00010676
The sample code is as below:
program get_PID
implicit none
character(200) :: line
call system('wmic cpu get ProcessorId >pid2.txt ' )
open (1,file='pid2.txt')
read (1,*) line
read (1,*) line
CLOSE (1)
end program
Do you have any advice?
The issue in your case is the encoding of the ouput from wmic. Windows uses UTF-16 as default. Fortran cannot handle this encoding yet. Referring to the help of Intel Fortran, only UTF-8 is supported as described here.
Therefore you have to change the encoding of the output to ANSI and/or your local codepage. This can be done by piping the result of wmic through the more command as described on SO superuser site under combine-batch-wmic-ansi-unicode-output-formatting.
Please change your system call as follows:
call system('wmic cpu get ProcessorId | more >pid2.txt ' )
You'll get the processor ID information in your code now, as expected.
Hope it helps.
When I copy text files to USB flash memory with Qt on raspberry pi 3 , and when I open these text files on Windows , text file '\n' characters not seem to work on Windows.
I searched this topic and I saw that text file formats are different on Linux and Windows.So I have to copy Linux based text files to Flash Memory with Qt and open these files on Windows.
There are a few characters which can indicate a new line. The usual ones are these two:
'\n' or '0x0A' (10 in decimal) -> This character is called "Line Feed" (LF).
'\r' or '0x0D' (13 in decimal) -> This one is called "Carriage return" (CR).
Different Operating Systems handle newlines in a different way. Here is a short list of the most common ones:
DOS and Windows :
They expect a newline to be the combination of two characters, namely '\r\n' (or 13 followed by 10).
Unix (and hence Linux as well) :
Unix uses a single '\n' to indicate a new line.
Mac :
Macs use a single '\r'.
EDIT : As MSalters mentioned Mac OSX is Unix and uses \n. The single \r is ancient Mac OS9
I guess you are just transporting the file, not doing anything with it, but I can't think of another option than opening it and rewrite the line endings.
If you open the .txt file on Windows and read from it (with c++ or c++/Qt) and then write the lines as you get them to a new file, the line endings should then fit the Windows sepcifics.
You can read the file like this:
std::ifstream file;
file.open(filePath);
std::ofstream file2;
file2.open(filePath2);
while(std::getline(file, line))
{
file2<<line;
}
std::getline
At least the documentation states that getline searches for '\n', it should work on windows and Unix. If it doesn't, you can still set the delimeter to '\n'.
If you want to write the file 'Windowslike' on your raspberry, you can try to replace the '\n' characters with '\r\n'
It should look somehow like this:
std::string myFileAsString;
std::string toReplace = "\n";
std::string replaceWith = "\r\n";
myFileAsString.replace(myFileAsString.find(toReplace), toReplace.length(), replaceWith);
where find searches for '\n' and then replaces it with '\r\n'
replace
find
I read a file and find that there are 0x0D after any 0x0A.
I only know that it is the windows that do the convertion.
But I have used the binary mode, it cannot prevent it?
ifstream input(inputname, ios::binary);input.get(ch);
How do I avoid it. I only want to get the \n.
How about write file?
Thx in advance.
If you're on a system that does use \r\n line endings then opening a file in text mode will cause the system to automatically convert these to the standard \n without \r. Opening a file in binary mode prevents this conversion.
If you're on a system that does not use this convention then there's no mode that will convert the line endings. You will have to convert them manually yourself or preprocess the file using an external tool.
If you want to detect whether a file uses \r\n you'll have to do it manually. Scan through the text file and see if every \n is preceded by a \r.
As an alternative, instead of trying to preemptively detect what kind of line endings a file uses, you could simply add logic in your processing code to specially handle \r followed by \n. Something like:
for (int i=0; i<n; ++i) {
if ('\r' == text[i] && (i+1<n) && '\n' == text[i+1])
++i; // skip carriage return, just handle newline
if ('\n' == text[i])
handle newline...
else
handle other characters
}
Hmm. If you use binary mode, ios::binary tells the library that you want to read the file as it is in binary (uncooked, raw).Using msdos (some people nowadays call it windows-nt) lines in text-files are terminated by 0d0a. So if you dont want to see this two chars, you have to open the file in text-mode (just omit the ios::binary). Or you have to convert these files to unix-style by some utilities like dos2unix, but then, if you are on a windows system, e.g. notepad may not be able to display this files as expected...
I'm using std::getline() to read from a text file, line by line. However, the first call to getline is reading in the entire file! I've also tried specifying the delimeter as '\n' explicitly. Any ideas why this might be happening?
My code:
std::ifstream serialIn;
...
serialIn.open(argv[3]);
...
std::string tmpStr;
std::getline(serialIn, tmpStr, '\n');
// All 570 lines in the file is in tmpStr!
...
std::string serialLine;
std::getline(serialIn, serialLine);
// serialLine == "" here
I am using Visual Studio 2008. The text file has 570 lines (I'm viewing it in Notepad++ fwiw).
Edit: I worked around this problem by using Notepad++ to convert the line endings in my input text file to "Windows" line endings. The file was written with '\n' at the end of each line, using c++ code. Why would getline() require the Windows line endings (\r\n)?? Does this have to do with character width, or Microsoft implementation?
Just guessing, but could your file have Unix line-endings and you're running on Windows?
You're confusing the newline you see in code ('\n') with the actual line-ending representation for the platform (some combination of carriage-return (CR) and linefeed (LF) bytes).
The standard I/O library functions automatically convert line-endings for your platform to and from conceptual newlines for text-mode streams (the default). See What's the difference between text and binary I/O? from the comp.lang.c FAQ. (Although that's from the C FAQ, the concepts apply to C++ as well.) Since you're on Windows, the standard I/O functions by default write newlines as CR-LF and expect CR-LF for newlines when reading.
If you don't want these conversions done and would prefer to see the raw, unadulterated data, then you should set your streams to binary mode. In binary mode, \n corresponds to just LF, and \r corresponds to just CR.
In C, you can specify binary mode by passing "b" as one of the flags to fopen:
FILE* file = fopen(filename, "rb"); // Open a file for reading in binary mode.
In C++:
std::ifstream in;
in.open(filename, std::ios::binary);
or:
std::ifstream in(filename, std::ios::binary);