Qt：c ++：如何读取“.dat”文件

Question

I have a ".dat" file that contains "1"s and "-1"s as a sequence in a vertical representation (ie: each element is in a single line.).

I am trying to read the file as follow:

char buf[30];
QFile sequence("Sequences.dat");
sequence.open(QFile::ReadOnly);
for(int sym=0; sym<29; sym++){
    char c = symbols[sym] = sequence.readLine(buf,sizeof(buf));
    symbols[sym] = c;
}
sequence.close();

however, the result is nothing like my sequence as seen below:

what did I did wrong ?

Answer 1

Check the readLine API doc: the return value is the number of bytes read, while the line is read into the buf array, which is overwritten at each iteration. Note that the first symbol of the inspected array is a '\\0' (empty string), probably because the last line of your file is empty.