CODEWITHSUNDEEP
qtqt5qtcore
balajeerc
balajeerc

Reputation: 4098

QTextStream readAll() removes Newlines

I am using QFile and QTextStream to first read a file and then write the read contents unmodified back into the same file. Here is the code:

QFile inFile("file.txt");
if(!inFile.open(QFile::ReadOnly | QFile::Text))
{
    qCritical() << "ERROR: Unable to open input file: " << "file.txt";
    exit(1);
}
QTextStream inStream(&inFile);
QString fileContents = inStream.readAll();
inFile.close();

QFile outFile("file.txt");
if(!outFile.open(QFile::WriteOnly | QFile::Text))
{
    qCritical() << "ERROR: Unable to open output file: " << "file.txt";
    exit(1);
}

QTextStream outSream(&outFile);
outSream << fileContents;
outFile.close();

However, this transforms the file.txt given below:

1
2
3
4
5

into

12345

i.e. newlines are getting removed in this process. Why is this happening? How can I prevent it?

Upvotes: 1

Views: 3033

Answers (3)

Yet Zio
Yet Zio

Reputation: 37

The solution is to not use QFile::Text or QIODevice::Text, if you are reading, just use QIODevice::ReadOnly , in that way you can also figure out the exact line ending used and handle them appropriately. I had this problem with Mac(CR) or '\r' line ending while opening with QIODevice::Text.

Upvotes: 1

Shihe Zhang
Shihe Zhang

Reputation: 2771

About QIODevice::Text in openMode the official document says.

When reading, the end-of-line terminators are translated to '\n'. When writing, the end-of-line terminators are translated to the local encoding, for example '\r\n' for Win32.

It says Win32,while working on Win64,Qt5.8 I found it works differently. With QIODevice::Text in openMode, QIODevice::readAll() remove all '\r','\t'.

And talk about \n,they are replaced by \r whatever openMode is using. May be removed if using QIODevice::Text mode.

Upvotes: 1

Jens
Jens

Reputation: 6329

The QIODevice::Text flag passed to open() tells Qt to convert Windows-style line terminators (\r\n) into C++-style terminators (\n). Are you operating in Windows? You should be able to see the \r\n in a binary editor on the input and the output file.

Upvotes: 2

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