Questions and answers

How do I read a text file in Qt?

by Chase Collins

How do I read a text file in Qt?

When you write data, you first call file. open(QIODevice::WriteOnly) and then write data to it. Similarly, to get data out of a file, you will need to call file. open(QIODevice::ReadOnly) and then read the data.

How do I read a text file line by line in Qt?

Since Qt 5.5 you can use QTextStream::readLineInto . It behaves similar to std::getline and is maybe faster as QTextStream::readLine , because it reuses the string: QIODevice* device; QTextStream in(&device); QString line; while (in. readLineInto(&line)) { // }

How do you write to a text file in Qt?

This can be changed using QTextStream::setCodec(). To write text, we can use operator<<(), which is overloaded to take a QTextStream on the left and various data types (including QString) on the right: QFile file(“out. txt”); if (!

How do I read a binary file in Qt?

Reading & Interpreting Binary file in Qt

  1. Read the file: QFile file(iFile); if (!file. open(QIODevice::ReadOnly)) return; QByteArray iContents = file. readAll();
  2. Get the length ushort c3 = 0xFF; c3 = iContents. at(2); // c3 should be “BE” hex. printf ( “%0x %d\n”, c3, c3 );

How do I read a JSON file in Qt?

reading JSON file in Qt5

  1. QFile file;
  2. file. setFileName(“/tmp/settings.json”);
  3. file. open(QIODevice::ReadOnly | QIODevice::Text);
  4. QJsonDocument settdoc;
  5. settdoc. fromBinaryData(file. readAll());
  6. qDebug() << settdoc. isNull();

How do you create a QT file?

2 Answers

  1. bool QFile::open ( OpenMode mode ) [virtual] […]
  2. bool QDir::mkdir ( const QString & dirName ) const. Creates a sub-directory called dirName.
  3. bool QDir::mkpath ( const QString & dirPath ) const. Creates the directory path dirPath.

How do I rename a file in Qt?

Re: rename file name

  1. open the text file(a. txt),and read the contents of it and modify some of it.
  2. write the modified contents in a new file(b.txt);
  3. delete a.txt.
  4. rename b. txt to a. txt.

How do you write a binary file in Qt?

Reading/writing data to binary file

  1. QFile file( “MyFile” );
  2. if( file. open( QFile::WriteOnly | QFile::Truncate ) )
  3. for( int i = 0; i < 10; i++ )
  4. qint32 exampleNum = 42;
  5. file. write( ( char * )( &exampleNum ), sizeof( exampleNum) );
  6. file. close();