CODEWITHSUNDEEP
c++qt
user1895683
user1895683

Reputation: 61

Compare two different values in c++

I iterate over a QByteArray which contains words. I will compare the array content with a given word (QString). 

for(QByteArray::iterator it = content.begin(); it != content.end(); it++){
    if(content.at(*it) == word){
        ...
    }
}

the compiler say on line (if(content.at ..)) : invalid conversion from 'char' to 'const char*' [-fpermissive]

how can i compare the values in this case?

Chris

Upvotes: 2

Views: 3286

Answers (5)

djf
djf

Reputation: 6757

I iterate over an qbytearray which contains words from a file. I will compare each word with a given word.

Thanks for the clarification. In that case1 I would convert the QByteArray to QString and then split it into individual words which can then be trivially compared. 

// QByteArray is implicitly convertible to QString
QString allWords = yourByteArray;
// split the string at each whitspace or newline
QStringList aWordlist = allWords.split(QRegExp("[\s\r\n]"), QString::SkipEmptyParts)

for (QStringList::iterator it=aWordlist.begin(); it != aWordlist.end(); ++it) 
{ 
   // it points to the next word in the list
   if (*it == word)
   {
       ...
   }
}

1I'm assuming that you can't change the fact that you receive the file contents as byte array. Otherwise, it would probably be better to open a QFile and read the contents from there.

How can i compare the values in this case?

According to the QString documentation, QString can be compared to QByteArray without iterating. So you could simply say:

QString word("Hello");
QByteArray bytes("hi");

if (word == bytes)
{ 
  ...
}

Upvotes: 1

user1895683
user1895683

Reputation: 61

I solved the problem: (QString word;)

void MainWindow::startSearching()
{
    word = ui->passwordTxt->toPlainText();
    string a;
    fstream inputFile;
    inputFile.open(fileName.data());

    while(!inputFile.eof()){
        inputFile >> a;
        if(a == word.toStdString()){
       //anything
            break;
        }
    }
    inputFile.close();
}

Upvotes: 0

gled
gled

Reputation: 121

I think I know what you want to do and the problem is not so much with the comparison as with the fact that you have stored your text in a QByteArray rather than a QString, or some kind of container such as a QVector, etc.

You need to look into different ways of reading in data from the QFile class. Check out the docs here:

QFile

QIODevice

Upvotes: 0

Ivaylo Strandjev
Ivaylo Strandjev

Reputation: 71019

*it is a byte and you try to compare it to a word(i.e. a sequence of chars). I am not sure what you are trying to do but maybe you should compare content.at(*it) to the first char in the word?

Upvotes: 0

nullptr
nullptr

Reputation: 11058

QByteArray contains bytes. QString contains a string, that is a sequence of characters. A single byte cannot be compared to a sequence of bytes.

Upvotes: 1

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