ASCII Number to Strings & Chars

[ttimt]

I search for help online for a whole day, maybe 2.
I outputted strings to its ascii value to a file by using the for loops and char .at()

all these output went well, but how can i read it back from the file?

i tried qt library and native c++ (not problem in codeblocks, but i want to have gui)

I'm not sure how to use char array below because I wont know how long the string is, how many chars are there.
And in my file, its not only 1 line of code. For example, when i input

ABCD
AAAA
BBBB

my file will become

65 66 67 68
65 65 65 65
66 66 66 66

ifstream myFile("abc.txt");
 
        while(myFile >> a >> a1 >> a2){
 
 
             a = a - 1;
             a = a1 - 1;
             a= a2 - 1;
             QString abc = QChar( a + a1 + a2);
             ui->aLine->setText(abc);
}

ifstream myFile("abc.txt");

        while(myFile >> a >> a1 >> a2){

                
             a = a - 1;
             a = a1 - 1;
             a= a2 - 1;
             QString abc = QChar( a + a1 + a2);
             ui->aLine->setText(abc);
}

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when i use just these codes below, it will only shows the first character of the whole strings.
And is there a way to make the abc still usable outside the loop? cause i need to set it after the loops right? and it always shows not declared.

myFile >> a
             QString abc = QChar( a );
             ui->aLine->setText(abc);

myFile >> a
             QString abc = QChar( a );
             ui->aLine->setText(abc);

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QFile mFile("abc.txt");
    mFile.open(QIODevice::ReadOnly | QIODevice::Text);
    QDataStream in(&mFile);
 
in >> a; // Not sure what's next. it keeps error

QFile mFile("abc.txt");
    mFile.open(QIODevice::ReadOnly | QIODevice::Text);
    QDataStream in(&mFile);

in >> a; // Not sure what's next. it keeps error

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[ChrisW67]

Your first code snippnet makes no sense, and I cannot see its connection to the stated input and output.

A QChar is a single character, and a QString is a collection of them. You can access a single character from a QString using QString::at(). You can get the character's Unicode code point from QChar::unicode(). You probably do not need either QString or QChar to do this task.

QDataStream is not the correct tool to read a text file. See QTextStream

Generic C++ code that already works stills works in the presence of Qt. The use of Qt in your program does not magically make the rules of C++ disappear. Variables have the same scope in Qt-using programs as they do in any other C++ program.

[ttimt]

well, can u pls show the code?
my file have numbers, so i can still use qtextstream? and i'm gonna edit the file extension to some random thing.
I have integers in my file, and when i read it, i want it to convert to chars and to QString. Whenever it meets a new line, it saves it in a new QString.

And btw, what's the difference of qfile and qiodevice? they seems to have the same function. qiodevice::readonly , qfile::readonly.

thx

[amleto]

my file have numbers, so i can still use qtextstream?
Yes. why don't you try it...

[ttimt]

void reset1::on_pushButton_clicked()
{
 
    QFile chk("configp.dll");
    chk.open(QFile::ReadOnly);
 
    if(chk.exists()){
        chk.rename(QString("configp1.dll"));
 
        QTextStream in(&chk);
        QString w;
        w = in.readLine().;
 
 
        ui->label_3->setText(w);
 
    }else{
        ui->label->setText("Password not Found! Reset Password Fail");
        ui->label_3->setText("Press cancel to go back");
    }
}

void reset1::on_pushButton_clicked()
{

    QFile chk("configp.dll");
    chk.open(QFile::ReadOnly);

    if(chk.exists()){
        chk.rename(QString("configp1.dll"));

        QTextStream in(&chk);
        QString w;
        w = in.readLine().;


        ui->label_3->setText(w);

    }else{
        ui->label->setText("Password not Found! Reset Password Fail");
        ui->label_3->setText("Press cancel to go back");
    }
}

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my program becomes not responding. I solved it by putting 1 in readLine() and it wont show anything.
Also how do i convert these numbers to char? if i put .fromAscii() behind readline it shows "no matching function for call to 'QString::fromAscii();"

This is how i input it.

QFile config("configp.dll");
config.open(QIODevice::WriteOnly | QIODevice::Text);
QTextStream out(&config);



for (int i = 0; i < ui->aLine->text().length(); i++)
{
char x =ui->aLine->text().toAscii().at(i);
out << int(x) << " ";
}out << endl;

[ChrisW67]

Are you deliberately trying to confuse?

From your first post, you have a text file containing ASCII text:

ABCD
AAAA
BBBB

ABCD
AAAA
BBBB

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you wish to transform into a text file containing more ASCII text:

65 66 67 68
65 65 65 65
66 66 66 66

65 66 67 68
65 65 65 65
66 66 66 66

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Your first batch of code does some sort of mangling of a single value based on the three values streamed from the file and doesn't attempt to output anything to a file. In you last post you are renaming an open file, checking whether it exists, all to do something with a password?

Your original problem is trivially met with:

QFile input("input.txt");
QFile output("output.txt");
if (input.open(QIODevice::ReadOnly)) {
    if (output.open(QIODevice::WriteOnly)) {
        bool needSpace = false;
        char c;
        while (input.getChar(&c)) {
            if (c < ' ') {  // new line and other control chars
                output.putChar(c);
                needSpace = false;
            }
            else {
                if (needSpace)
                    output.putChar(' ');
                output.write( QByteArray::number(c) );
                needSpace = true;
            }
        }
    }
}

QFile input("input.txt");
QFile output("output.txt");
if (input.open(QIODevice::ReadOnly)) {
    if (output.open(QIODevice::WriteOnly)) {
        bool needSpace = false;
        char c;
        while (input.getChar(&c)) {
            if (c < ' ') {  // new line and other control chars
                output.putChar(c);
                needSpace = false;
            }
            else {
                if (needSpace)
                    output.putChar(' ');
                output.write( QByteArray::number(c) );
                needSpace = true;
            }
        }
    }
}

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or, using QTextStream:

if (input.open(QIODevice::ReadOnly)) {
    if (output.open(QIODevice::WriteOnly)) {
        QTextStream in(&input);
        QTextStream out(&output);
        char c;
        bool needSpace = false;
        while (!in.atEnd()) {
            in >> c;
            if (c < ' ') {
                out << c;
                needSpace = false;
            }
            else {
                out << (needSpace? " ": "") << QByteArray::number(c);
                needSpace = true;
            }
        }
    }
}

if (input.open(QIODevice::ReadOnly)) {
    if (output.open(QIODevice::WriteOnly)) {
        QTextStream in(&input);
        QTextStream out(&output);
        char c;
        bool needSpace = false;
        while (!in.atEnd()) {
            in >> c;
            if (c < ' ') {
                out << c;
                needSpace = false;
            }
            else {
                out << (needSpace? " ": "") << QByteArray::number(c);
                needSpace = true;
            }
        }
    }
}

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There are many ways to achieve this.

[ttimt]

absolutely not, the rename file doesn't work so i actually juz put there... :/
this is the output to file code,no problem with output, just showing the code
when i enter words on lineedit, it will be saved to numbers in configp.dll
66 66 66
67 67 67
68 68 68

QFile config("configp.dll");
    config.open(QIODevice::WriteOnly | QIODevice::Text);
    QTextStream out(&config);
 
    for (int i = 0; i < ui->aLine->text().length(); i++)
{
   char x =ui->aLine->text().toAscii().at(i);
   out << int(x) << " ";
}
out << endl;
 
    for (int i = 0; i < ui->pLine->text().length(); i++)
{
   char x =ui->pLine->text().toAscii().at(i);
   out << int(x)<< " ";
}
out << endl;
 
    for (int i = 0; i < ui->fLine->text().length(); i++)
{
   char x =ui->fLine->text().toAscii().at(i);
   out << int(x)<< " ";
}
out << endl;
 
    for (int i = 0; i < ui->gLine->text().length(); i++)
{
   char x =ui->gLine->text().toAscii().at(i);
   out << int(x)<< " ";
}

QFile config("configp.dll");
    config.open(QIODevice::WriteOnly | QIODevice::Text);
    QTextStream out(&config);

    for (int i = 0; i < ui->aLine->text().length(); i++)
{
   char x =ui->aLine->text().toAscii().at(i);
   out << int(x) << " ";
}
out << endl;

    for (int i = 0; i < ui->pLine->text().length(); i++)
{
   char x =ui->pLine->text().toAscii().at(i);
   out << int(x)<< " ";
}
out << endl;

    for (int i = 0; i < ui->fLine->text().length(); i++)
{
   char x =ui->fLine->text().toAscii().at(i);
   out << int(x)<< " ";
}
out << endl;

    for (int i = 0; i < ui->gLine->text().length(); i++)
{
   char x =ui->gLine->text().toAscii().at(i);
   out << int(x)<< " ";
}

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so how im gonna get string x= aaa , string y = bbb ,string z = ccc which inputted earlier?

QFile chk("configp.dll");
    chk.open(QIODevice::ReadOnly);
    if(chk.exists()){
 
//what should i type here when file exists to get the above (string x, y, z)
 
    }else{
        ui->label->setText("File not Found!");
        ui->label_3->setText("Press cancel to go back");
    }

QFile chk("configp.dll");
    chk.open(QIODevice::ReadOnly);
    if(chk.exists()){

//what should i type here when file exists to get the above (string x, y, z)

    }else{
        ui->label->setText("File not Found!");
        ui->label_3->setText("Press cancel to go back");
    }

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[ChrisW67]

Right. So, is this the question you wanted to ask?

I have a file containing three lines like:

65 65 65 66
66 66 67
67 68 69

65 65 65 66
66 66 67
67 68 69

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where each number indicates the ASCII value of a character in decimal. I would like to read this file and produce three strings containing the characters from each line, in the example:

AAAB
BBC
CDE

AAAB
BBC
CDE

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How can I do this using Qt classes?

[ttimt]

ya,
string1 = AAAB;
string2 = bbc
string3 = cde

[ChrisW67]

QStringList result;
QFile input("input.txt");
if (input.open(QIODevice::ReadOnly)) {
    while (!input.atEnd()) {
        QByteArray line = input.readLine().trimmed();
        QString s;
        foreach(QByteArray num, line.split(' ')) {
            s.append( QChar(num.toShort()) );
        }
        result << s;
    }
}
qDebug() << result;

QStringList result;
QFile input("input.txt");
if (input.open(QIODevice::ReadOnly)) {
    while (!input.atEnd()) {
        QByteArray line = input.readLine().trimmed();
        QString s;
        foreach(QByteArray num, line.split(' ')) {
            s.append( QChar(num.toShort()) );
        }
        result << s;
    }
}
qDebug() << result;

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[ttimt]

i want it to appear on a lineedit,
ui->lineEdit->setText(s);
ui->lineEdit->setText(result);
neither works
error: no matching function for call to 'QLineEdit::setText(QStringList&)'

and, i'm newbie. do i need to use this codes 3 times? the QStringList is aaab, bbc or cde or all?

(im using gui, so qDebug() wont work here right?)